I 


GBPT  OF 


^apg-sa^ 
EX  LIBR1S 


/<Si 


*~~~ 


~ 

' 


CEMENTS,  LIMES,  AND 


THEIR    MATERIALS,    MANUFACTURE, 
AND    PROPERTIES 


BY 


EDWIN  C.    ECKEL,    C.E. 

Associate,  American  Society  of  Civil  Engineers;  Member,  Society  of  Chemical 
Industry;  Assistant  Geologist,  U.  S.  Geological  Survey 


FIRST    EDITION 

SECOND   THOUSAND. 


NEW  YORK 

JOHN    WILEY    &    SONS 
LONDON:  CHAPMAN  &  HALL,   LIMITED 
1909. 


.••-••.•:•• 

', '    ;''/.' 

:  ' '  ' 


Engineering 
Library 


Copyright,  1905 

BY 

EDWIN  C.  ECKEL 


ahr  Srirnttfir  Prraa 

Eobrrl  Urummanft  and  (Contpanii 

Krai  fork 


PREFACE. 


OF  all  the  non-metallic  structural  materials  in  use  by  the  engineer, 
the  most  important  at  the  present  day  are  those  included  under  the 
head  of  Cementing  Materials,  using  that  term  in  its  broadest  sense  to 
include  not  only  the  hydraulic  .cements  proper,  but  the  limes,  plasters, 
and  allied  materials.  This  importance  is  due  in  large  part  to  the 
advances  which  have  been  made,  in  American  practice,  in  the  methods 
of  manufacturing  these  products,  for  these  advances  in  technology 
have  resulted  in  supplying  the  engineer  with  uniform  and  high-grade 
cementing  materials  at  prices  low  enough  to  permit  of  great  increase 
in  their  uses. 

In  consequence  of  this  growth  of  the  industries  based  on  cementing 
materials  an  extensive  literature  on  the  subject  has  developed.  This 
literature  is,  however,  widely  scattered  through  the  pages  of  many 
technical  and  scientific  journals  and  transactions,  and  no  adequate 
summary  of  the  matter  from  an  American  point  of  view  has  yet 
appeared.  The  present  volume  is  the  result  of  an  attempt  to  provide 
such  a  summary,  covering  the  composition  and  character  of,  the  raw 
materials,  the  methods  of  manufacture,  and  the  properties  of  the  vari- 
ous cementing  materials. 

In  a  work  of  this  scope*  many  points  of  interest  can  only  be  sug- 
gested, not  discussed  in  detail.  For  the  convenience  of  those  who 
wish  to  make  further  studies  of  such  subjects,  very  complete  reference 
lists  have  been  placed  in  almost  every  chapter  of  this  volume.  These= 
lists  necessarily  contain  the  names  of  some  papers  and  articles  pub- 
lished in  European  periodicals  or  transactions,  but  most  of  the  titles, 
cited  will  be  found  to  be  from  readily  accessible  American  journals.. 
A  working  engineer  rarely  has  at  his  command  an  extensive  technical 
library,  so  that  references  to  the  proceedings  of  some  German  scientific; 
society  are  apt  to  prove  a  vexation  rather  than  an  aid. 

ill 

813219 


iv  PREFACE. 

•       X       . 

Stress  has  been  laid,  in  the  discussion  of  manufacturing  methods, 
on  the  general  chemical  and  physical  principles  which  underlie  these 
methods  rather  on  the  details  which  differ  at  every  plant  and  may 
change  with  every  year.  So  far  as  possible,  however,  such  details  as 
bear  on  labor,  power,  and  costs  have  been  carefully  discussed,  and  it 
is  believed  that  the  estimates  furnished  are  entirely  reliable. 

The  writer's  acknowledgments  are  due  to  Engineering  News,  Munici- 
pal Engineering,  Engineering  Record;'* Engineering  and  Mining  Journal, 
Cement,  and  The  Iron  Age  for  permission  to  use  illustrations  and  to 
reprint  parts  of  articles  which  had  appeared  first  in  their  columns.  To 
an  even  greater  extent  he  is  indebted  to  the  chemists  and  managers 
of  American  cement-,  lime-,  and  plaster-plants,  and  to  manufacturers 
of  different  lines  of  machinery,  for  data  and  illustrations  which  they 
have  kindly  furnished  for  use  in  this  volume. 

It  may  not  be  out  of  place  to  state  that  this  volume  was  planned 
and  partly  written  in  1901.  If  it  had  been  published  at  that  date  the 
words  " probably"  and  "possibly"  would  not  have  occurred  so  fre- 
quently as  they  do  in  the  present  work,  for  at  that  time  the  writer  felt 
a  cheerful  certainty  in  regard  to  many  points  which  now  seem  less 
obvious.  A  wider  personal  experience,  taken  in  connection  with  the 
remarkable  changes  which  have  recently  affected  both  the  theory  and 
practice  of  cement-manufacture,  has  resulted  in  a  more  cautious  treat- 
ment of  certain  phases  of  the  subject. 

WASHINGTON,  D.  C.,  March  6,  1905.  EDWIN  C.  ECKEL. 


TABLE  OF  CONTENTS. 


PAGE 

LlST  OF   TABLES xxv 

LlST    OF    ILLUSTRATIONS XXix 

INTRODUCTION. 

GROWTH  OF  THE  CEMENTING  INDUSTRIES „ 1 

CLASSIFICATION  AND  RELATIONSHIPS  OF  CEMENTING  MATERIALS. 2 

Simple  cementing  materials 3 

Plasters 4 

Limes  and  magnesia 5 

Complex  cementing  materials 7 

Silicate  cements 7 

Hydraulic  limes 8 

Natural  cements 8 

Portland  cement ,.  .-9 

Puzzolan  cements. 9 

Oxychloride  cements 9 

CHEMICAL  AND  PHYSICAL  DATA  EMPLOYED  IN  DISCUSSION 10 

Atomic  weights  of  elements 10 

Chemical  compounds 12 

Heat-units » 12 

Metric  conversion  tables 12 


PART   I.    PLASTERS. 
CHAPTER   I. 

COMPOSITION,   DISTRIBUTION,   AND    EXCAVATION   OF  GYPSUM. 

Chemical  composition  of  gypsum 14 

Varieties  of  gypsum 15 

Physical  properties  of  gypsum 15 

Anhydrite 15 

Occurrence  and  origin  of  gypsum  deposits 15 

Geologic  distribution  of  gypsum  deposits 16 

Distribution  of  gypsum  in  the  United  States 16 

v 


VI  TABLE  OF  CONTENTS. 


Distribution  of  gypsum  in  Canada 25 

References  on  gypsum  deposits 26 

Excavation  and  handling  of  rock  gypsum 29 

Mining  methods 29 

Working  gypsum-earth  deposits 30 


CHAPTER  II. 

CHEMISTRY    OF   GYPSUM-BURNING.      MANUFACTURE    OF   PLASTERS. 

Chemistry  of  gypsum-burning } 31 

Classification  of  plasters 32 

Commercial  classification 32 

Manufacture  of  plaster  of  Paris,  "cement  plaster",  and  wall  plaster 33 

Grinding  gypsum  and  plaster 34 

Calcining  in  ovens 37 

Calcining  in  kettles 37 

Designs  of  kettles 39 

Temperatures  attained 44 

Actual  equipment  of  kettle-process  plants 44 

Calcining  in  rotary  cylinders 46 

Cummer  system 46 

Mannheim  system 49 

Addition  of  retarders  and  accelerators 50 

Wall  plaster 51 

Packing  weights 52 

Costs  of  plaster-manufacture 52 

Analyses  of  gypsum  used  in  actual  practice 53 

References  on  plaster-manufacture 55 


CHAPTER   III. 

COMPOSITION,    PROPERTIES,    AND   TESTS    OF   PLASTERS. 

Chemical  composition  of  plasters 56 

Theoretical  composition 56 

Actual  composition  of  plaster  of  Paris 56 

Actual  composition  of  cement  plasters 56 

Physical  properties  and  tests  of  plasters 57 

Weight  and  specific  gravity 57 

Fineness  of  calcined  plasters 58 

Tensile  strength. 58 

Compressive  tests  and  effect  of  same 61 

Adhesive  tests 62 

Rate  of  set  and  hardening 64 

Theory  of  the  action  of  retarders  and  accelerators 64 

Materials  used  as  retarders 64 

Effect  of  retarders  on  strength  of  plasters 65 


TABLE* OF  CONTENTS.  vii 

PAGE 

Use  of  accelerators. 66 

Hardening  gypsum  and  plaster 67 

References  on  properties  and  tests  of  plasters 67 

CHAPTER   IV. 

FLOORING-PLASTERS    AND    HARD-FINISH    PLASTERS. 

Characters  of  the  two  groups 68 

Flooring-plasters 68 

Composition  of  flooring-plaster , 68 

Van't  Hoff's  investigations 69 

Composition  and  structure  of  flooring-plaster 69 

Change  of  volume  on  hardening 70 

Increase  of  weight  on  hardening 73 

Methods  of  manufacture 75 

Uses  of  flooring-plasters 75 

Hard-finish  plasters 76 

Definition 76 

Keene's  cement 76 

Manufacture 76 

Composition 77 

Properties 78 

Mack's  cement 78 

References  on  dead-burned  and  hard-finish  plasters 78 

CHAPTER   V. 

STATISTICS    OF    THE    GYPSUM    AND    PLASTER    INDUSTRIES. 

Total  use  of  gypsum  in  the  United  States,  1900-1903 79 

Distribution  of  total  by  uses,  1900-1903 79 

Production  in  the  United  States,  by  uses,  1890-1903 80 

Production  in  the  United  States,  by  States  and  classes  of  product,  1902-1903  81 

Production  by  States,  1890-1901 i'j 83 

Imports  of  gypsum  and  plaster,  1900-1903 84 

World's  production  of  gypsum,  1893-1903 86 


PART  II.    LIMES. 
CHAPTER   VI. 

COMPOSITION,     ORIGIN,     AND     GENERAL     CHARACTERS    OF    LIMESTONES. 

Origin  of  limestones 88 

Varieties  of  limestone 89 

Chemical  composition  of  limestone „ 89 

Presence  of  magnesia 90 

Presence  of  silica,  alumina,  iron,  and  otlier  impurities. 91 


vui  TABLE  OF   CONTENTS. 

PAGE 

Geologic  and  geographic  distribution  of  limestones. 91 

Reference  list  on  limestones 92 

Shells  as  sources  of  lime 94 

CHAPTER  VII. 

LIME-BURNING. 
jit 

Theoretical  considerations : Q6 

The  burning  of  a  non-magnesian  limestone 96 

The  burning  of  a  magnesian  limestone 97 

Classification  of  limes. '; 97 

Methods  and  costs  of  lime-burning 93 

Heat  requiremets  in  lime-burning . .  98 

Types  of  lime-kilns 99 

Intermittent  kilns 99 

Vertical  kilns  with  mixed  seed 101 

Vertical  kilns  with  separate  seed 103 

Ring  or  chamber  kilns.     (Hoffmann  kilns.) 106 

Utilization  of  carbonic  acid  gas  from  lime-kilns 108 

Costs  of  lime-manufacture 109 

Detailed  estimates  of  cost 109 

Actual  costs  of  lime-manufacture  in  1900 110 

Statistics  of  the  lime  industry 112 

CHAPTER  VIII. 

COMPOSITION    AND    PROPERTIES    OF   LIME. 

General  properties 115 

High-calcium  vs.  magnesiun  limes 115 

Composition  of  commercial  high-calcium  limes 116 

Lean  or  poor  limes 117 

Composition  of  commercial  magnesian  limes 118 

Lime-slaking 118 

Effect  of  impurities  present 120 

Expansion  of  volume 120 

Effect  of  the  presence  of  magnesia 120 

Method  of  slaking  lime  in  ordinary  practice 120 

Use  of  lime  mortars 121 

Strength  of  lime  mortars 122 

CHAPTER  IX. 

HYDRATED    LIME!    ITS    PREPARATION   AND    PROPERTIES. 

Preparation  of  hydrated  lime 124 

Grinding'the  quicklime 124 

Mixing  with  water 125 

Sieving  the  product 126 


TABLE  OF  CONTENTS.  IX 

PAGE 

Standards  for  packing,  etc 128 

Cost  of  equipment •  128 

Tests  of  hydrated  lime 128 

Mixture  of  hydrated  lime  and  Portland  cement 129 

References  on  hydrated  lime 129 

CHAPTER  X. 

MANUFACTURE    AND    PROPERTIES    OF   LIME-SAND    BRICKS. 

Definition 130 

Early  history  of  the  industry,  1838-1856 130 

Theory  of  lime-sand  brick  manufacture 132 

General  processes  of  lime-sand  brick  manufacture 134 

Necessary  properties  of  the  sand 134 

Drying  the  sand.  . 135 

Necessary  properties  of  the  lime 135 

Methods  of  slaking  the  lime 136 

Proportions  of  mixture 138 

Methods  of  molding 138 

Methods  of  hardening  the  bricks 138 

Costs  of  plant  and  manufacture 140 

Composition  of  lime-sand  bricks 142 

Physical  properties  of  lime-sand  bricks 142 

Tests  of  lime-sand  bricks .' .  142 

Comparison  with  clay  bricks '. 145 

Comparison  with  natural  sandstone 146 

Statistics  of  the  lime-sand  brick  industry 146 

List  of  references  on  lime-sand  bricks .  146 


PART  III.    MAGNESIA  AND   OXYCHLORIDE  CEMENTS. 

CHAPTER  XL 

SOURCES    AND    PREPARATION    OF   MAGNESIA. 

Sources  of  magnesia 148 

Magnesite  as  a  source  of  magnesia 148 

Composition  and  character  of  magnesite 148 

Occurrence  and  origin  of  magnesite .* 149 

Distribution  of  magnesite  deposits 149 

Foreign  localities 149 

American  localities , „ .    150 

Production  and  imports  of  magnesite  and  magnesia 152 

Analyses  of  commercial  magnesite 152 

Effects  of  heating  magnesite 154 

Methods  of  burning  magnesite 154 

Composition  of  the  product 155 

Use  of  magnesite  for  preparation  of  carbonic  acid,  etc. 155 


X  TABLE  OF  CONTENTS. 

PAGE 

Magnesian  limestones  as  sources  of  magnesia 156 

Occurrence  of  magnesium  limestones  in  the  United  States 156 

Analyses  of  magnesium  limestones * 156 

Extraction  of  magnesia  from  magnesian  limestones 157 

Scheibler  process 157 

Closson  process 158 

'Sea-water  and  brines  as  sources  of  magnesia 158 

Extraction  of  magnesia  from  sea-wateff .• 159 

References  on  magnesite,  sources  of  magnesia,  etc 159 

CHAPTER  XII. 

MAGNESIA   BRICKS   AND    OXYCHLORIDE    CEMENTS. 

Magnesia  bricks 160 

Manufacture  of  magnesia  bricks 160 

Composition  of  magnesia  bricks 161 

Physical  properties  of  magnesia  bricks 161 

References  on  magnesia  bricks , 162 

Oxychloride  cements 162 

Sorel's  discovery 162 

Manufacture  of  oxychloride  cements 162 

Manufacture  and  properties  of  Sorel  stone.  .  .    163 

Manufacture 163 

Strength 165 

Durability 165 

Costs " 167 

References  on  oxychloride  cements,  Sorel  stone,  etc 167 

PART  IV.    HYDRAULIC  LIMES,   SELENITIC  LIMES,  AND 
GRAPPIER  CEMENTS. 

CHAPTER  XIII. 

THE   THEORY    OF   HYDRAULIC    LIMES. 

-General  discussion ' 168 

"The  Hydraulic  Index 168 

The  Cementation  Index 170 

Use  of  the  Cementation  Index  in  classification 171 

Definition  of  hydraulic  limes 172 

Subgroups  of  hydraulic  Ifmes 173 

CHAPTER   XIV. 

EMINENTLY   HYDRAULIC    LIMES:    GRAPPIER    CEMENTS. 

Eminently  hydraulic  limes .' 174 

Composition  of  the  ideal  hydraulic  lime 471 

Composition  of  the  actual  product 175 

Raw  materials ;   hydraulic  limestones . .  . .  „ „  0     176 

Burning  hydraulic  lime „ 179 

Slaking  the  lime , ,  .    177 


TABLE  OF  CONTENTS.  xi 


'Sieving  the  product 180 

Analyses  of  hydraulic  limes 182 

Weight  and  specific  gravity 182 

Tensile  and  compressive  strength ; 183 

Ratio  compressive  to  tensile  strength 183 

Proportions  for  mortars  and  concretes 184 

Grappier  cements 185 

Definition 185 

Composition  of  grappier  cements 185 

Physical  properties  of  grappier  cements 185 

CHAPTER   XV. 

FEEBLY    HYDRAULIC    LIMES!    SELENITIC    LIMES. 

Feebly  hydraulic  limes 187 

General  character  and  index 187 

Analyses  of  raw  material 187 

Analyses  of  feebly  hydraulic  limes 188 

Tensile  strength • 188 

Compressive  strength 1 189 

Selenitic  lime:  Scott's  cement. 190 

Composition 190 

Manufacture  of  selenitic  limes 190 

Tensile  strength  of  selenitic  limes 191 

Compressive  strength  of  selenitic  limes 192 


PART  V.  NATURAL  CEMENTS. 
CHAPTER  XVI. 

DEFINITION    AND    RELATIONS    OF   NATURAL    CEMENTS. 

Lack  of  homogeneity  in  the  group .\  .  194 

Definition  of  natural  cements 195 

Relations  of  natural  cements  to  others 195 

Cementation  Index  of  natural  cements 196 

Statement  of  the  index . . 196 

Example  of  calculation 196 

Basal  assumptions ; 197 

Use  of  the  Cementation  Index 198 

Values  of  the  index  for  natural  cements 198 

Subgroups  of  the  class  of  natural  cements 198 

CHAPTER  XVII. 
RAW  MATERIAL:  NATURAL-CEMENT  ROCK. 

•Composition  of  natural-cement  rock 201 

American  natural-cement  rocks 201 


xii  TABLE  OF  CONTENTS. 

PAGE 

General  discussion 201 

Georgia 202 

Illinois 203 

Indiana-Kentucky 204 

Kansas 205 

Maryland 205 

Minnesota . 205 

New  York .".... ?. 207 

North  Dakota 210 

Ohio 210 

Pennsylvania , 210 

Texas 211 

Virginia 212 

West  Virginia-Maryland 213 

Wisconsin 213 

European  natural-cement  rocks 214 

General  characters  and  subgroups 214 

Natural  Portlands 214 

Roman  cements 214 

Natural-cement  materials  of  Belgium 215 

Natural-cement  materials  of  England 217 

Excavation  of  natural-cement  rock 219 

Methods 219 

Costs 220 

References  on  natural-cement  rock 221 


CHAPTER  XVIII. 

MANUFACTURE  OF  NATURAL  CEMENTS. 

Processes  of  manufacture 223 

Burning  practice  and  theory 223 

Chemical  changes  during  burning 223 

Relation  of  composition  to  degree  of  burning 224 

Losses  in  burning 224 

Types  of  kiln  used 225 

Fuel  consumption  in  burning  natural  cement ' 233 

Hard  and  soft  clinker 234 

Seasoning  and  slaking 235 

Grinding  the  clinker 236 

General  practice 236 

Actual  mill  equipments  of  American  plants 237 

Types  of  grinding  machinery  employed 238 

Jaw  crushers 238 

Cone  grinders:  crackers 238 

Rolls 239 

Millstones .  239 


TABLE  OF  CONTENTS.  xiii 

PAGE 

Edge-runners 243 

Centrifugal  grinders 243 

Ball-grinders 243 

Impact  pulverizers 244 

Separating  systems , 245 

Power  required  in  grinding 246 

Fineness  actually  attained . .  , 246 

Packing  weights 248 

Costs  of  manufacture 248 

Cost  of  raw  material 248 

Labor  costs 248 

Fuel  costs 249 

Total  costs  per  barrel 249 

References  on  manufacturing  methods 250 


CHAPTER  XIX. 

COMPOSITION   AND   PROPERTIES   OF  NATURAL   CEMENTS. 

Chemical  composition  of  natural  cement 252 

Georgia 252 

Illinois 252 

Indiana-Kentucky ...... 252 

Kansas 254 

Maryland .  . 254 

Minnesota.  .  .  .- » . .  .  254 

New  York 256 

North  Dakota .V. 259 

Pennsylvania 259 

West  Virginia-Maryland 259 

Wisconsin .  . .  .  260 

Belgium 260 

England 230 

France „ 260 

Germany- Austria. 261 

Physical  properties  of  natural  cements .  263 

Weight  and  specific  gravity 263 

Rapidity  of  set 263 

Effects  of  gypsum  or  plaster  on  natural  cements 264 

Effect  of  salt  on  strength 267 

Tensile  strength 267 

Effect  of  sand  on  tensile  strength .  272 

Compressive  strength 274 

Effect  of  heating 275 

Ratio  of  compressive  to  tensile  strength 275 

Modulus  of  elasticity 277 


xiv  TABLE  OF  CONTENTS. 

CHAPTER  XX. 

SPECIFICATIONS    FOR   NATURAL    CEMENTS. 

PAGE 

New  York  State  Canals,  1896 278 

Rapid  Transit  Subway,  New  York  City,  1900-1901 278 

Engineer  Corps,  United  States  Army,  1901 279 

American  Society  for  Testing  Materials,  1904. 281 

Comparison  of  various  specifications f. 282 

Definition 282 

Specific  gravity . . 282 

Fineness „ 282 

Strength . . 283 

Product  actually  delivered ......  28% 

CHAPTER  XXI. 

HISTORY,  STATISTICS  AND   PROSPECTS   OF  THE  NATURAL-CEMENT  INDUSTRY., 

History  of  the  industry 285 

Dates  of  establishment  of  various  plants 288 

Statistics  of  the  industry. 289 

Localization  of  the  industry ; 289 

Production  in  1901,  1902,  and  1903,  by  states • 290 

Total  product  in  the  United  States,  by  years,  1818-1904. 291 

Prospects  of  the  industry „..  »„....  292 

PART  VI.    PORTLAND    CEMENT. 

CHAPTER  XXII. 

PORTLAND  CEMENT:   PRELIMINARY  STATEMENTS. 

Origin  of  the  name  "Portland" 294 

Present  use  of  the  term  "Portland" .  295 

Definition  of  Portland  cement , 297 

Composition  and  constitution 297 

General  discussion . . 297 

Cementation  Index. 298 

Silica-alumina  ratio 299 

Raw  materials  available  for  Portland  cement  manufacture 300 

Classification  of  raw  materials  by  composition  and  properties 301 

Types  of  raw  materials  used 302 

Relative  importance  of  various  types 304 

Valuation  of  deposits  of  cement  materials 304 

Factors  involved 304 

Chemical  composition 304 

Physical  character 305 

Amount  available .  305 


TABLE  OF  CONTENTS.  xv 


Location  with  respect  to  transportation  routes 305 

Location  with  respect  to  fuel  supplies 305 

Location  with  respect  to  markets 306. 

CHAPTER  XXIII. 

LIMESTONES. 

Limestones  in  general 307 

Varieties  and  origin 307 

Composition  of  limestones 308 

Impurities  of  limestones 309 

Physical  characters 310 

Effects  of  heating 311. 

Pure  hard  limestones 312 

Use  in  cement  manufacture 312 

Composition  of  hard  limestones  actually  used 312 

Prospecting  and  examining  limestone  deposits 315 

Preliminary  examination 316- 

Detailed  mapping  and  sampling 317 

Chalk  and  other  soft  limestones 318 

Origin  of  chalk 318 

Distribution  of  chalk  in  the  United  States. 319 

Physical  properties 320 

Composition  of  chalk  and  soft  limestones  actually  used 320 

Examining  chalk  deposits 321 

List  of  references  on  chalks  and  soft  limestones 322 

CHAPTER  XXIV. 

ARGILLACEOUS    LIMESTONE:    CEMENT   ROCK. 

Definition 323 

"Cement  rock"  of  the  Lehigh  district ,  324 

Geology  of  the  district 324 

Character  and  composition  of  the  "cement  rock" „ 328 

Quarry  practice  in  the  Lehigh  district . .  . ... 329 

Cement  production  of  the  district 331 

Probable  extension  of  the  district 331 

"Cement  rock  "  in  other  states .r 332 

Analyses  of  western  "cement  rocks" ,. 333 

List  of  references  on  "  cement  rock  " 333 

CHAPTER  XXV. 

FRESH-WATER   MARLS. 

Various  uses  of  the  term  "marl" 334 

Occurrence  of  marl  deposits 335 


xvi  TABLE  OF  CONTENTS. 


Origin  of  marl  deposits 336 

Geographic  distribution  of  marl  deposits 339 

Physical  characters  of  marl 340 

Chemical  composition  of  marl 341 

Analyses  of  marls  actually  used 342 

Examining  marl  deposits 343 

List  of  references  on  marls 346 

**r  ••«'.-  •<• 

CHAPTER  XXVI. 

ALKALI  WASTE:  BLAST-FURNACE  SLAG. 

Use  of  by-products  as  cement  materials 348 

Alkali  waste 348 

Leblanc  process  waste 348 

Ammonia  process  waste 349 

Analyses  of  alkali  wastes 349 

List  of  references  on  alkali  waste  as  a  cement  material 350 

Blast-furnace  slag 350 

Slags  in  general 351 

Slags  used  as  Portland  cement  materials 352 

CHAPTER  XXVII. 

CLAYS,  SHALES,  AND   SLATES. 

Relation  of  clays,  shales,  and  slates 353 

Clays 353 

Origin  of  clays ' „ 353 

Composition  of  clays 354 

Clays  used  in  cement  manufacture » . . . .  354 

Analyses  of  clays  actually  used. „ 355 

Shales.  .  .' 357 

Origin  and  composition 358 

Analyses  of  shales  used  as  cement  material.  . . .  „ . . 358 

Examination  of  clay  deposits 360 

List  of  references  on  clays  and  shales ...» 360 

Slates 363 

Geographic  distribution  of  slates 363 

Composition  of  slates 364 

Slates  used  in  cement  manufacture. 365 

References  on  slates. 0 366 

CHAPTER   XXVIII. 

EXCAVATING   THE   RAW   MATERIALS. 

Quarrying 367 

Stripping 368 


TABLE  OF  CONTENTS.  xvii 


Quarry  practice 368 

Working  in  levels 370 

Use  of  steam  shovels 370 

Costs  of  steam-shovel  work 373 

Crushing  and  drying  in  the  quarry 374 

Mining 375 

Dredging 375 

Marl  pumping 376 

Cost  of  raw  materials  at  mill 378 

Loss  on  drying,  etc 378 

Costs  of  quarrying  or  mining 378 

Costs  of  marl  dredging 379 

References  in  quarrying,  etc 381 

CHAPTER  XXIX. 

CALCULATION  AND  CONTROL  OF  THE  MIX. 

Theoretical  composition  of  Portland  cement 382 

Influence  of  normal  constituents  on  the  cement 384 

Maximum  lime  content  of  mixture 384 

Minimum  lime  content  of  mixture 385 

Magnesia. 386 

Silica 386 

Alumina 387 

Iron  oxide 388 

Sulphur.' 388 

Alkalies 388 

Phosphorus 389 

Influence  of  intentionally  added  fluxes 390 

Calculating  mixtures  of  untried  materials 391 

Cementation  Index.  .  „ . 391 

Use  of  the  formula  in  proportioning  mixtures 392 

Calculating  mixtures  in  current  work 393 

Composition  of  the  mixture 394 

Methods  of  control 395 

Changes  in  composition  during  manufacture 395 

CHAPTER  XXX. 

PREPARING  THE  MIXTURE  FOR  THE  KILN. 

Methods  of  preparation 398 

Dry  methods 399 

Drying  the  raw  materials , 399 

Percentage  of  water  in  raw  materials 399 

Methods  and  costs  of  drying 400 

Grinding  and  mixing 404 

General  methods. .  .  40-1 


xviii  TABLE  OF  CONTENTS. 

PAGH 

Plans  of  actual  plants  .......  .......................................  404 

Actual  equipments  of  dry-process  plants  ..............................  408 

List  of  references  on  dry-process  plants  and  methods  ...................  410 

Methods  used  with  slag  limestone  mixtures  ................................  411 

General  methods  ...............  ......................  .  .............  411 

Composition  of  the  slag  .............................................  412 

Granulating  the  slag  .......  ........................................  413 

Drying  the  slag  ............  .  .........  .,„  ............  .  ...............  413 

Grinding  the  slag  .................  >  .  .  .  .............................  414 

Composition  of  the  limestone  ..................  „  .............  ,  .......  414 

Economics  of  using  slag-limestone  mixtures  ...........................  414 

References  on  slag-limestone  mixtures  .................  '.  ..............  415 

Blast-furnace  methods  of  making  cement  .................................  415 

Wet  methods  of  preparation  ............................................  416 

Disadvantages  of  wet  methods  ......................................  416 

Treatment  of  the  marl  and  clay  .....................................  417 

Power  and  output  in  wet  grinding  ...................................  417 

Agitating  the  mix  ........  „  ..........  ...................  ..............  418 

Old-style  wet  methods  .............................  .  .  .  .  .  ............  419 

Actual  equipment  of  wet-process  plants  ............  ...................  420 

List  of  references  on  wet-process  plants  and  methods  ..................  421 

General  crushing  practice  in  cement  plants  ................................  422 

Necessity  for  fine  grinding.  ...  ............................  ..........  423 

Actual  fineness  attained  in  practice  .................  .................  424 

Gradual  vs.  one-stage  reduction  ......................................  424 

Present  day  systems  ......................  .........................  425 

The  omission  of  separators  in  cement  plants  ...........................  426 

Advantages  of  separators  ....................  .  ......................  426 

Disadvantages  of  separators  ....................  .....................  427 

Uniformity  of  product  destroyed  .................................  427 

Great  fineness  prevented  ...................  .....................  427 


CHAPTER  XXXV. 

STANDARD    TYPES    OF    CRUSHING    AND    PULVERIZING    MACHINERY. 

Classification  of  grinding  machinery  ......................................  429 

Class  1  .  Jaw  crushers  ..................................................  430 

Class  2.  Cone  grinders  or  gyratory  crushers  ...............................  430 

Class  3.  Rolls  .........................................................  433 

Class  4.  Millstones  .................................  ....................  437 

Class  5.  Edge-runners:  Dry  pans  ........................................  437 

Class  6.  Centrifugal  grinders  ...........................................  438 

Huntingdon  mill  .............................................  438 

Griffin  mill  ...............  .  .................................  .  440 

Kent  mill  ...............  ...................................  .443 

7.  Ball  grinders  ....................  .  ............  .................  447 

Kominuter.  .                          ....................................  448 


TABLE  OF  CONTENTS.  xix 

PAGE 

Ball  mills 452 

Tube  mills. 457 

Pebbles  for  tube  mills .463 

Class  8.  Impact  pulverizers 465 

Raymond  pulverizer 466 

Williams  mill 466 

CHAPTER  XXXII. 
CEMENT  BURNING:  FIXED  KILNS. 

Classes  of  fixed  or  stationary  kilns 469 

1.  Dome  or  ordinary  intermittent  kilns 470 

2.  Dome  kilns  with  drying  accessories 471 

Johnson  kiln „ . .   471 

3.  Ring  or  Hoffmann  kiln 472 

4.  Continuous  shaft  kilns 474 

Dietzsch  kiln 474 

Aalborg  or  Schofer  kiln.  . . . 474 

Hauenschild  kiln .  475 

Schwarz  kiln 477 

Reference  list  for  fixed  kilns 478 

CHAPTER  XXXIII. 

THE    ROTARY   KILN. 

Early  history 480 

Summary  of  burning  process 481 

Shape  and  size 482 

Feeding  coal  to  the  kiln 486 

Gas-burners  for  rotary  kilns 489 

Kiln  linings 490 

Actual  fuel  consumption  and  output 492 

CHAPTER  XXXIV. 

HEAT   CONSUMPTION    AND    HEAT   UTILIZATION. 

Theoretical  heat  requirements 497 

Purposes  for  which  heat  is  required 497 

Heat  utilized  in  evaporation  of  water 498 

Heat  utilized  in  decomposition  of  clay 498 

Heat  utilized  in  dissociation  of  sulphates 499 

Heat  utilized  in  dissociation  of  carbonates 499 

Temperature  required  for  clinkering 499 

Heat  utilized  in  heating  the  mix 500 

Total  theoretical  heat  requirements " 501 

Heat  losses  in  practice 502 

Sources  of  loss  of  heat 502 

Heat  carried  out  in  flue  dust 502 


XX  TABLE  OF  CONTENTS. 

PAGE 

Sources  of  heat  supply 503 

Heat  supplied  by  combustion  of  fuel 503 

Heat  supplied  by  chemical  combinations „ 504 

Heat  derived  from  the  clinker 504 

Heat  derived  from  the  stack-gases 504 

Estimates  and  tests  of  heat  distribution 505 

Newberry's  estimates 505 

Helbig's  estimates \ > .  . .  .  505 

Results  of  actual  tests : 505 

Richard's  tests 506 

Carpenter's  tests .  508 

Summary  of  estimates  and  tests .....';. 509 

Heat  utilization  and  economics 509 

List  of  references  on  heat  requirements,  etc 510 

CHAPTER  XXXV. 

REQUISITES   AND   TREATMENT   OF  KILN   FUELS. 

Coal 512 

Characters  of  kiln  coals „ .  512 

Analyses  of  kiln  coals 512 

References  on  coal-fields 513 

Crushing  coal 514 

Drying  coal 515 

Pulverizing  coal 515 

Power  and  output  in  coal  grinding 519 

Total  cost  of  coal  preparation 520 

Fire  and  explosion  risks 520 

List  of  references  on  coal  drying,  grinding,  etc 521 

Oil 522 

Use  of  oil  in  rotary  kilns 522 

List  of  references  on  petroleum 522 

Natural  gas 522 

Use  of  natural  gas  in  kilns 522 

Analyses  and  thermal  value  of  gas 523 

List  of  references  on  natural  gas 523 

Producer  gas 524 

General  note » 524 

Producer  gas  from  wood  and  lignite 524 

Composition  of  producer  gas 525 

Charcoal 526 

CHAPTER  XXXVI. 

CLINKER   COOLING,    GRINDING,    AND   STORAGE.      USE   OF  GYPSUM. 

Clinker  cooling 527 

General  methods  of  clinker  cooling 527 

Pan  conveyors,  rolls,  and  sprinkling „ .  . .  „ „ .  .   528 


TABLE  OF  CONTENTS.  xxi 

PAGE 

Stationary  tower  coolers. 528 

One-stage  rotary  cooler. 529 

Atlas  two-stage  rotary  cooler 529 

Clinker  grinding 530 

Power  and  machinery 531 

Increase  in  fineness 531 

Actual  equipment  of  various  plants 532 

Use  and  effects  of  gypsum  or  plaster 534 

Form  in  which  the  calcium  sulphate  is  used 535 

Effect  of  calcium  sulphate  on  set  of  cement 538 

Effect  of  calcium  sulphate  on  strength  of  cement 543 

Methods  of  using  gypsum  or  plaster 545 

Analyses  of  gypsum  and  plaster  actually  used 545 

Effect  of  various  other  salts  on  set  of  cement 545 

List  of  references  on  use  of  calcium  sulphate,  chloride,  etc 547 

Storage  and  packing 548 

Necessity  for  storage 548 

Designs  of  storage  buildings  and  bins 548 

Testing  at  the  mill 549 

Packing  weights 551 

CHAPTER  XXXVII. 

COSTS   AND    STATISTICS. 

Costs  of  manufacture  of  Portland  cement 554 

Factors  of  cost 554 

Cost  of  land  and  quarries 555 

Cost  of  equipment  and  erection 555 

Total  capital  required 556 

Current  administrative  expenses 557 

Cost  of  excavating  raw  materials 557 

Total  power  required ? 557 

Cost  of  coal  for  kilns  and  power 558 

Cost  of  gypsum  used 558 

Distribution  and  cost  of  labor 558 

Estimates  of  total  cost  per  barrel 559 

Statistics  of  the  American  Portland  cement  industry 561 

Total  production  in  the  United  States,  1870-1904 562 

Production  by  States,  1901,  1902,  1903 562 

Production  in  the  Lehigh  district,  1890-1903 564 

Imports  of  foreign  Portland,  1899-1903 564 

CHAPTER  XXXVIII. 

CONSTITUTION,    SETTING,    PROPERTIES,   AND    COMPOSITION. 

Limitations  of  chemical  analyses 566 

Constitution  and  setting  properties 566 


xxii  TABLE  OF  CONTENTS. 

PAGE 

Available  methods  of  investigation 566 

Synthetic  investigations , 567 

Microscopic  investigations 568 

Theories  of  constitution 569 

Setting  properties  of  Portland  cement 572 

Replacement  of  silica  by  other  acids 573 

Replacement  of  alumina  by  iron  oxide. . 573 

Replacement  of  lime  by  magnesia.  ..'..»$ 574 

Replacement  of  lime  by  other  bases 574 

References  on  the  constitution  of  Portland  cement 575 

Composition  of  Portland  cement.  .  . , 575 

Gradual  change  in  composition  since  1850 575 

Analyses  of  American  Portland  cements 576 

Standard  methods  for  analysis 576 


CHAPTER  XXXIX. 

PHYSICAL    PROPERTIES.      TESTING   METHODS. 

Physical  properties  of  Portland  cement 583 

Value  of  tests  for  fineness 584 

Specific  gravity 585 

Setting  properties.  . .- 586 

Tensile  strength , . . . .  586 

Compressive  strength 588 

Ratio  of  compressive  to  tensile  strength 589 

Modulus  of  elasticity 591 

Sand  cement  or  silica  cement 592 

List  of  references  on  sand  cement 596 

Effect  of  heating  on  Portland  cement. 597 

Effects  of  salt  and  freezing 598 

Effects  of  exposure  to  sea-water 602 

Standard  methods  of  testing,  Am.  Soc.  C.  E 603 


CHAPTER  XL. 

SPECIFICATIONS    FOR    PORTLAND    CEMENT. 

New  York  State  Canals,  1896 - 614 

Rapid  Transit  Subway,  N.  Y.  City,  1900-1901 615 

Department  of  Bridges,  N.  Y.  City,  1901 616 

Engineer  Corps,  U.  S.  Army,  1902. 617 

U.  S.  Reclamation  Service,  1904 620 

Canadian  Society  of  Civil  Engineers 622 

Concrete  Steel  Engineering  Company 624 

British  Standard  Specifications 625 

American  Society  for  Testing  Materials,  1904 629 


TABLE  OF  CONTENTS.  Xxiii 

PART   VII.    PUZZOLAN    CEMENTS. 
CHAPTER  XLI. 

PUZZOLANIC    MATERIALS    IN    GENERAL. 

PAGE 

Definition  of  puzzolanic  materials • 632 

Natural  puzzolanic  materials 632 

Pozzuolana ..».-..- 633 

Trass .". . . . Y. 635 

Santorin 635 

Arenes,  etc , .  . : 637 

Range  and  average  composition  of  natural  puzzolanic  materials 638 

Natural  puzzolanic  materials  in  the  .United  States 638 

Artificial  puzzolanic  materials.  .,.....,.. » 639 

Burnt  clay 639 

Blast-furnace  slag 639 

CHAPTER-  XLII. 
SLAG  CEMENT:  REQUISITES  AND  TREATMENT  OF  THE  SLAG. 

Summary  of  general  methods  of  manufacture. 641 

Composition  of  the  slag 641 

Requisite  chemical  composition 641 

Composition  of  slags  actually  used. , 642 

Selection  of  slags 644 

Granulating  the  slag 644 

Methods  of  granulating  the  slag . 645 

Effects  of  granulating  the  slag 646 

Increased  hydraulicity  due  to  granulation * . .  647 

Desulphurization  due  to  granulation 648 

Drying  the  slag *#v*  649 

Types  of  dryers  used 649 

Rotary  dryers 649 

Vertical  dryers 652 

CHAPTER  XLIII. 
SLAG  CEMENT:    LIME,  MIXING,  AND  GRINDING. 

Character  and  treatment  of  the  lime 653 

Composition  of  the  lime 653 

Burning  the  lime 654 

Slaking  the  lime ' 654 

Sieving  and  grinding  the  lime 655 

Mixing  and  grinding 655 

Proportions  of  lime  and  slag 655 

Calculating  the  mixture 656 

Pulverizing  and  mixing 657 


xxiv  TABLE  OF  CONTENTS. 

PAGE 

Regulation  of  set 658 

General  practice  at  various  plants 659 

Costs  of  manufacture  of  slag  cement. 663 

Production  of  slag  cement 664 

List  of  references  on  the  manufacture  of  slag  cement 664 

CHAPTER  XLIV. 

•& 
SLAG  CEMENT:  COMPOSITION  AND  PROPERTIES. 

Identification  of  slag  cements 666 

Chemical  composition  of  slag  cements. i 666 

Elements  present 667 

Analyses  of  slag  cements 667 

Physical  properties  of  slag  cements 668 

Specific  gravity 668 

Color 669 

Rapidity  of  set 670 

Strength 670 

Resistance  to  mechanical  wear. 670 

Rates  of  compressive  to  tensile  strength 670 

List  of  references  on  properties  and  testing  of  slag  cements 671 

Specifications  for  slag  (puzzolan)  cements 672 

CHAPTER  XLV. 

SLAG   BRICKS   AND   SLAG   BLOCKS. 

Definition  of  the  two  groups 675 

Slag  bricks 675 

Methods  of  manufacture 676 

Practice  at  various  plants 677 

Hardening  in  steam-cylinders 680 

Slag  blocks 685 

INDEX  TO  SUBJECTS 691 


LIST  OF  ILLUSTRATIONS. 


PAGE 

1.  Map  of  U.  S.  showing  location  of  gypsum  deposits  and  plaster-plants Opp.  14 

2.  Map  of  Kansas,  showing  location  of  gypsum  deposits 19 

3.  Map  of  New  York,  showing  extent  of  gypsum-bearing  formations 20 

4.  Map  of  the  gypsum  deposits  of  Ohio 22 

5.  Nipper  for  coarse  crushing  of  gypsum 34 

6.  Cracker  for  intermediate  reduction  of  gypsum 35 

7.  Stedman  disintegrator,  opened 36 

8.  Stedman  disintegrator,  cage  construction 37 

9.  Construction  and  setting  of  gypsum  kettles 38 

10.  Four-flue  kettle,  with  accessories,  dismounted ! 39 

11.  Kettle  with  sectional  bottom 40 

12.  Section  of  100-ton  plaster  mill,  kettle  process 42 

13.  Plan  of  Electric  Plaster  Co.'s  mill,  Blue  Rapids,  Kansas 45 

14.  Plan  of  plaster  mill,  rotary  calciner  process 47 

15.  Cummer  rotary  calciner  for  plaster 48 

16.  Broughton  mixer 51 

17.  Hair-picker 51 

18.  Effect  of  sand  on  tensile  strength  of  plaster 60 

18a.  Effect  of  sand  on  compressive  strength  of  plaster 62 

19.  Map  of  the  U.  S.,  showing  location  of  principal  lime-producing  centers .  .Opp.  88 

20.  Plan  and  section  of  lime  kilns 102 

21.  Aalborg  kiln  for  lime  burning 103 

22.  Keystone  lime  kiln 105 

23.  O'Connell  lime  kiln 107 

24.  Eldred  lime-hydrating  system 125 

25.  Campbell  lime-hydrater 127 

26.  Schwarz  drying  and  mixing  machine. 137 

27.  Kiln  used  for  burning  hydraulic  lime 178 

28.  Section  of  hydraulic  lime  plant,  Malain,  France 181 

29.  Tensile  strength  of  Lafarge  (grappier)  cement 186 

30.  Tensile  strength  of  feebly  hydraulic  limes 189 

31.  Tensile  strength  of  plain  hydraulic  and  selenitic  limes 192 

32.  Compressive  strength  of           "          "           "           "     193 

33.  Map  of  U.  S.,  showing  location  of  natural-cement  plants Opp.  194 

34.  Tensile  strength  of  various  classes  of  cement 21& 

xxv 


LIST  OF  ILLUSTRATIONS. 

PAGE 

:35.  Loading  cars,  Speed  natural-cement  quarry 219 

.36.  Crusher  for  raw  rock  at  Speed's  mill 220 

37.  Sections  of  kilns  used  in  natural-cement  plants 226 

.38.  Elevation  and  section  of  Campbell  kiln 227 

39.  Plan  and  details  of  Campbell  kiln 227 

40.  Kilns  of  the  Lawrence  natural-cement  plant 228 

41.  Kilns  and  coal  conveyor  at  .the  Speed  plant 229 

42.  Kilns  and  kiln  housing,  Speed  plant.  .?. 230 

43.  Kilns  and  loading  tracks,  Fort  Scott,  Kansas 233 

44.  Sections  of  cracker  for  natural-cement  grinding 239 

45.  Bturtevant  rock-emery  mill. ,,. 240 

46.  Sturtevant  rock-emery  millstone 240 

47.  Section  of  Sturtevant  mill 241 

48.  Berthelet  separator 244 

49.  Installation  of  Berthelet  separating  system 245 

50.  Effect  of  plaster  on  set  of  natural  cement ' 265 

51.  Effect  of  salt  on  compressive  strength,  natural  cement 266 

52.  "       "     "     "     tensile                "              "            "      266 

53.  "       "     "     "          "                    "              "            "      267 

51  Tensile  strength  of  Louisville  cement 268 

55.  "             "         "  Lehigh  natural  cements 268 

56.  "             '*        "  Cumberland  natural  cements 268 

57.  ' '             "         "  .Akron  and  Cumberland  natural  cements 270 

58.  "             ' '        "  natural  cements,  Cairo  Bridge  tests 271 

.59.        ' '    '          "         "  Rosendale  cements 272 

63.  "             "        "  natural  cements,  Saulte  Ste.  Marie 272 

-61.  Effect  of  sand  on  tensile  strength,  natural  cements 273 

G2.  Tensile  tests,  Saulte  Ste.  Marie 274 

j63.  Map  of  the  U.  S.,  showing  location  of  Portland-cement  plants OpP-  294 

64.  Percentage  of  total  output  from  different  raw  materials 303 

•65.  Working  a  thick  limestone  bed 311 

66.  Working  heavy  horizontal  bed  of  limestone 315 

67.  Tunnel  in  cement  rock 330 

08.  Open  cut  in  cement  rock 331 

69.  Pit  in  heavy  shale  bed 358 

70.  Shale  pit  worked  on  two  levels 358 

71.  Stripping  a  flat,  shallow  bed 368 

72.  View  of  typical  limestone  quarry 369 

73.  Temporary  tracks  laid  to  face. 369 

74.  Cableway  in  cement-rock  quarry 370 

75.  ""        "         "         "          "       ,. 371 

76.  Shale  pit  worked  in  two  levels 371 

77.  Hoisting  from  quarry  worked  in  levels 372 

78.  Steam  shovel  in  cement-rock  quarry 372 

79.  Steam  shovel  in  limestone  quarry 374 

80.  Dredge  at  marl  plant. 376 

81.  Harris  system  of  marl-pumping 377 

.•82.  Marl-drying  plant,  Hecla  P.  C.  Co 401 


LIST  OF  ILLUSTRATIONS.  xxvii 

PAGE 

83.  Elevation  of  stack-drier,  Edison  P.  C.  Co 403 

84.  Installation  of  kominuters  and  tube-mills 405 

85.  Plan  of  plant,  Lawrence  Cement  Co 406 

S6.  Plan  of  plant,  Hudson  P.  C.  Co 407 

87.  External  view  of  Gates  crusher 431 

88.  Sectional  view  of  Gates  crusher 432 

89.  Elevation  of  rock-crushing  system,  Edison  P.  C.  Co 434 

90.  View  looking  down  between  rolls,  Edison  P.  C.  Co 435 

91.  Plan  and  elevation  of  Edison  rolls 346 

-92.   Dry-pan 438 

93.  Huntingdon  mills  at  Atlas  plant 439 

94.  Section  of  Griffin  mill 441 

95.  Interior  of  Kent  mill 444 

96.  Lindhard  kominuter 446 

97.  "  "         447 

98.  Exterior  view  of  kominuter 451 

99.  Gates  ball-mill 453 

100.  Transverse  section  of  Gates  ball-mill 454 

101.  Automatic  ball-mill  feeder 456 

102.  Gates  tube-mill 458 

103.  Setting  of  Davidsen  tube-mill 461 

104.  Exterior  view  of  Bonnot  tube-mill 463 

105.  Williams  mill,  casing  opened 466 

106.  ' '  "   ,  section 467 

107.  Dome  kiln 470 

108.  Plan  and  section  of  Johnson  kiln ; 472 

1C9.  Section  of  Hoffman  kiln 473 

110.  Plan  of  Hoffman  kiln 474 

111.  Dieczsch  kiln 475 

112.  Section  of  Schofer  kiln 476 

113.  Hauenschild  kiln 477 

114.  Schwarz  kiln 477 

115.  Exterior  of  rotary  kiln 480 

116.  Plan  and  elevation  of  rotary  kiln 481 

117.  Driving  mechanism  of  rotary  kiln 482 

118.  Details  of  60-foot  rotary  kiln 483 

119.  Raw-material  storage  bin. ;  .   484 

120.  Section  of  Edison  150-foot  rotary  kiln 485 

121.  Coal-burning  arrangement  for  rotary  kiln 487 

122.  "          "  "  "       "         " 488 

123.  Kirkwood  gas  burner  for  rotary  kiln 489 

124.  "  '•'••.•;."       applied  to  kiln 490 

125.  Arrangement  of  kiln  lining,  wet  process 493 

126.  "  ' '     ' '        "     ,  dry  process 493 

127.  Coarse-toothed  rolls  for  lump  coal 514 

128.  Smooth  rolls  for  coal  crushing 515 

129.  Section  of  Smidth  ball-mill 517 

130.  Smidth  ball-mill,  external  view.  .  . 518 


xxviii  LIST  OF  ILLUSTRATIONS. 

PAGE 

131.  Tower  ccwler,  Buckhorn  P,  C.  Co 528 

132.  Atlas  two-stage  rotary  cooler 530 

133.  Effect  of  plaster  on  strength  of  Portland  cement 536 

134.  "      "       "       "         "        "          "            "  538 

135.  "      "       "        "    setting  time  of  Portland  cement 539 

136       tf      tl       lt       "         "        "     "           "            "  540 

137.  "      "       "       "         "        "      "          "            "     542 

138.  "      "       "       "   strength  of  Portlayfd  cement 543 

139.  Concrete-steel  bins,  Illinois  Steel  Co. Opp.  548 

140.  Plan  and  section  of  stock  house,  Hudson1?.  C.  Co 549 

141.  Foundation  plan  "       "          "            "            "      } 551 

142.  Plan  of  bins  in  stock  house,  Hudson  P.  C.  Co ." 551 

1 43.  Effect  of  fineness  on  tensile  strength „ 584 

144.  Effect  on  strength  of  regrinding  cement 585 

145.  Effect  of  temperature  on  setting-time „ 586 

146.  Tensile  strength  of  various  classes  of  cements 587 

147.  Effect  of  sand  on  tensile  strength 588 

148.  Effect  of  character  of  sand  on  tensile  strength 589 

149.  Ratio  of  compressive  tensile  strength.  • 590 

150.  Strength  of  sand-cement  mortar 593 

151.  "         "     "         "              "   595 

152.  "         "     "         "              "  595 

153.  Effect  of  salt,  etc.,  on  freezing-point 599 

154.  "      "     "       "     "  mortar 599 

155.  "      "     "       li     "        "      600 

156.  "      "     "       "     lt        " 600 

157.  "      "     "       "     "        "      601 

158.  "      "     "       "     "  compressive  strength 601 

159.  Effect  of  granulating  slag,  compression 647 

160.  "      "           "           ".tension 647 

161.  Ruggles-Coles  drier , 650 

162.  Vitry  slag-drier 652 

163.  Elevation  and  plan  of  Stewart  slag-cement  plant 660 

164.  Effect  of  hardening  in  air  and  water,  tensile  strength,  slag  cement 669 

165.  "      "         "          «*<*«<       tt    ^  compressive  strength,  slag  cement..  669 


LIST  OF  TABLES. 


PAGE 

1.  Production  of  structural  materials,  1902-1903 1 

2.  Value  of  cementing  materials  produced  in  the  United  States,  1900-1903. . .  2 

3.  Symbols  and  atomic  weights  of  elements H 

4.  Names  and  symbols  of  principal  compounds 12 

5.  Sizes,  capacity,  etc.,  of  Stedman  disintegrators 36 

6.  Temperatures  in  cement-plaster  manufacture 44 

7.  Sizes,  capacity,  etc.,  of  Broughton  mixers 50 

8.  Analyses  of  rock  gypsum  used  for  plaster 53 

9.  Analyses  of  gypsite  (gypsum  earth)  used  for  plaster 54 

10.  -Analyses  of  plaster  of  Paris 57 

11.  Analyses  of  cement-plasters 57 

12.  Fineness  of  calcined  plasters 58 

13.  Fineness  of  plasters  tested 59 

14.  Tensile  strength  of  plasters:  effect  of  sand 59 

15.  Tensile  strength  of  plasters 61 

16.  Effect  of  sand  on  compressive  strength  of  plasters 63 

17.  Adhesive  strength  of  plasters 63 

18.  Effect  of  retarders  on  strength  of  plasters 65 

19.  Effect  of  various  retarders  on  rate  of  set  of  plasters 66 

20.  Effect  of  accelerators  on  rate  of  set  of  plasters 67 

21.  Tensile  strength  of  Keene's  cement 78 

22.  Tensile  strength  of  American  Keene's  cement 78 

23.  Total  imports  and  production  of  gypsum  in  U.  S.,  1900-1903 79 

24.  Uses  of  gypsum,  1900-1903 79 

25.  Gypsum  production  of  the  U.  S.,  by  uses,  1890-1903 80 

26.  Gypsum  production  of  the  U.  S.,  by  States,  1902-1903 82 

27.  Production  and  volume  of  gypsum  in  U.  S.,  by  States,  1890-1901 83 

28.  Imports  of  gypsum  and  plaster,  1900-1903 85 

29.  Imports  of  gypsum  and  plaster,  by  countries,  1900-1903 86 

30.  World's  production  of  gypsum,  1893-1903 87 

31.  Analyses  of  various  molluscan  shells 95 

32.  Analyses  of  oyster-shells  and  oyster-shell  lime 95 

33.  Heat  and  fuel  required  in  burning  lime 99 

34.  Sizes,  capacity,  etc.,  of  Keystone  lime  kilns 106 

xxix 


xxx  LIST  OF  TABLES. 

PAGE 

35.  Cost  of  lime  manufacture  during  1900  in  ten  States Ill 

36.  Elements  of  cost  of  lime  manufacture,  in  percentages 112 

37.  Lime  production  of  the  U.  S.,  by  States,  1902-1903 113 

38.  Analyses  of  high-calcium  limes 116 

39.  Analyses  of  lean  limes 118 

40.  Analyses  of  magnesian  limes 119 

41.  Tensile  strength  of  magnesium  and  high-calcium  limes 122 

42.  Tensile  strength  of  lime  mortars. „"? 123 

43.'  Sizes,  capacity,  etc.,  of  Sturtevant  crushers 125 

44.  Capacity,  power,  etc.,  of  Campbell  lime-hydrater 126 

45.  Sizes,  etc.,  of  Jeffrey  separators 126 

46.  Tensile  strength  of  hydrated  lime 128 

47.  Percentage  composition  of  various  lime  silicates 133 

48.  Effect  of  fineness  of  sand  on  lime-sand  brick 135 

49.  Comparative  tests  of  magnesian  and  high-calcium  lime  bricks 136 

50.  Effect  of  percentage  of  lime  on  lime-sand  brick 138 

51.  Effect  of  hardening  methods  on  lime-sand  brick 139 

52.  Comparison  of  lime-sand  bricks  and  natural  sandstone '. 142 

53.  Physical  tests  of  lime-sand  brick 143 

54.  "          "     "     "      "        "    143 

55.  Compressive  strength  of  lirrie-sand  brick 144 

56.  Physical  tests  of  lime-sand  brick 144 

57.  Summary  of  tests  of  lime-sand  brick 145 

58.  Summary  of  tests  of  clay  brick 145 

59.  Summary  of  tests  of  natural  sandstones 146 

60.  Analyses  of  magnesite  from  Quebec,  Canada 152 

61.  Production  of  magnesite  in  U.  S.,  1891-1903 • 153 

62.  Imports  of  magnesia  and  magnesite,  1903 153 

63.  Analyses  of  magnesites 153 

64.  Analyses  of  calcined  magnesite  ( =  magnesia) 155 

65.  Analyses  of  highly  magnesian  limestones,  U.  S 157 

66.  Analyses  of  magnesia  bricks 161 

67.  Expansion  of  magnesia  bricks  on  heating 162 

68.  Compressive  strength  of  Sorel  stone 166 

69.  Composition  of  ideal  hydraulic  limestone  and  hydraulic  lime 175 

70.  Analyses  of  hydraulic  limestones  of  Teil,  France 176 

71.  Analyses  of  hydraulic  limestones:  France  and  Germany 176 

72.  Analyses  of  beds  in  hydraulic-lime  quarries  at  Malain,  France 177 

73.  Analyses  of  hydraulic  lime  before  slaking  (Teil,  France) 179 

74.  Analyses  of  hydraulic  limes:  France,  Germany,  and  England 179 

75.  Analyses  of  kiln  products,  Teil,  France 182 

76.  Analyses  of  hydraulic  limes,  after  slaking 182 

77.  Average  strength  of  hydraulic  limes 183 

78.  Tensile  strength  of  hydraulic-lime  mortar 183 

79.  Compressive  strength  of  hydraulic-lime  mortar 184 

80.  Analyses  of  grappier  cements 185 

81.  Tensile  strength  of  Lafarge  grappier  cement 186 

82.  Analyses  of  feebly  hydraulic  limestones .  187" 


LIST  OF  TABLES  xxxi 


83.  Analyses  of  feebly  hydraulic  limes 188> 

84.  Tensile  strength  of  feebly  hydraulic  limes 188 

85.  Compressive  strength  of  feebly  hydraulic  limes 190- 

86.  Tensile  strength  of  selenitic  limes 191 

87.  Compressive  strength  of  selenitic  limes , 192 

88.  Analyses  of  natural-cement  rock,  Utica,  111 204 

89.  ""        "        "  "         ",  Louisville  district 204 

90.  "        "       "  "         "    ,  Fort  Scott,  Kansas 205 

91.  "        "        "  "         ",  Cumberland-Hancock,  Md 206 

92.  "        "        "  "         "    ,  Mankato,  Minn 206 

93.  "        "       "  "         ",  Rosendale  district,  N.  Y 208 

94.  "         "        "  "         "    ,  Schoharie  Co.,  N.  Y 208 

95.  ..."         "        "  "         "    ,  Central  N.  Y 209 

96.  "         "        "  "         "    ,  Akron-Buffalo,  N.  Y 210 

97.  "        "       "  "         "    ,  North  Dakota 211 

98.  "        "       (t  "         ",Ohio 211 

99.  "         "        "  "         "    ,  Lehigh  district,  Pa 212 

100.  "         "        "  "         "    ,  Virginia 212 

101.  "        "       "  "         ",  Milwaukee  district,  Wis 213 

102.  "        "        "  "         "    ,  England 217 

103.  Fuel  consumption  in  American  natural-cement  plants 234 

104.  Power  required  in  grinding  natural  cement 246 

105.  Fineness  required  by  various  specifications 247 

106.  ' '        of  three  brands  natural  cement 247 

107.  Estimate  of  cost  of  natural-cement  manufacture 249 

108.  Daily  cost  report  of  natural-cement  plant 250 

109.  Analyses  of  natural  cements,  Ga 253- 

110.  "        "       "  "       ,  Utica,  111 253 

111.  "        "       "  "       ,  Louisville  district 253 

112.  "        "        "  "       ,  Ft.  Scott,  Kans 254 

113.  "        "       t{  "       ,  Potomac  district,  Md 255 

114.  "         "        "  "       ,  Minnesota 255- 

115.  "        "       "  "       ,  Rosendale  district,  N.  Y 256 

116.  "        "        "  "       ,  Central  N.  Y 258 

117.  "        "       "  "       ,  Akron-Buffalo  district,  N.  Y 258- 

118.  "        "       "  "       ,  North  Dakota 259 

119.  "        "       "  "       ,  Lehigh  district,  Pa 259 

120.  "        "       "  "       ,  Shepherdst'n-Antietam  district,  W.  Va.-Md .  260 

121.  "        "       tl  "       ,  Milwaukee  district,  Wis 260 

122.  "         "  natural  Portland  cements,  Belgium 261 

123.  "        "       ."       cements,  England 261 

124.  "         "        "  "       ,  France : 261 

125.  "         "        "  "       ,  Germany  and  Austria 262 

126.  Specific  gravity  of  American  natural  cements 263 

127.  Effect  of  aeration  on  setting  time  of  natural  cement 264 

128.  "     "    plaster     "         "        "    "          "          "     t 264 

129.  "       "        "         "  tensile  strength  of  natural  cement 265 

130.  "       "  sand          "         "          "        "          "          "  .  273- 


xxxii  LIST  OF  TABLES. 


131.  Compressive  tests  of  natural  cements 274 

132.  ' '         strength  of  4-inch  natural-cement  cubes 275 

133.  Effect  of  heating  on  compressive  strength 275 

134.  Relation  of  tensile  to  compressive  strength  of  natural-cement 276 

135.  "       "      "       "  "  "         "  Utica  natural  cement 276 

136.  Modulus  of  elasticity 277 

137.  Fineness  required  by  various  specifications 282 

138.  Strength          "       "          "~  "     -' 283 

139.  Cement  supplied  to  N.  Y.  Rapid-transit  subway,  1900-1901 283 

140.  Summary  of  natural-cement  tests,  1897-1900 284 

141.  Dates  of  establishment  of  natural -cement  industries  in  various  States.  .  .  .  288 

142.  Production  of  natural  cement  in  1901,  1902,  and  1903,  by  States. 290 

143.  Total  production  of  various  cements  in  U.  S.,  1818-1904 291 

144.  Character  of  Portland-cement  materials 301 

145.  Production  of  Portland  cement  from  various  materials 304 

146.  Analyses  of  hard  limestones  used  in  American  cement-plants 314 

147.  "        "purechalks  "     "          "  "  " 321 

148.  "         "clayey     "  "     "          "  "  " 321 

149:         "        "  Hudson  shale  and  slate  in  Pa.  and  N.  J 325 

150.  "        "  Trenton  limestones 326 

151.  "        "  Kittatinny  magnesian  limestone.  . 327 

152.  "         "  "cement-rock" 329 

153.  "         "  pure  limestone  used  for  mixing  with  cement  rock 329 

154.  Portland-cement  production  of  the  Lehigh  district,  1890-1902 332 

155.  Analyses  of  "cement-rock"  materials  from  the  Western  U.  S 333 

156.  Fineness  of  crude  marl 340 

157.  Analyses  of  marls  used  in  American  cement-plants 342 

158.  "         ' '  alkali  waste,  ammonia  process 349 

159.  ' '         "  iron-furnace  slags 351 

160.  "         "  normal  clays  used  in  American  cement-plants 355 

161.  "         "limey       "          "     "          "  "  " 353 

162.  "         "  normal  shales    "     "          "  "  "       357 

163.  "         "limey          "       M     "         "  "  "       \ 359 

.  164.         "         "  American  roofing  slates 364 

165.  Composition  of  American  roofing  slates 364 

166.  Analyses  of  slate  used  for  Portland  cement,  Rockmart,  Ga 365 

167.  Detailed  costs  of  steam-shovel  work 373 

168.  Effect  of  alumina 388 

169.  Analyses  of  raw  materials  containing  phosphoric  acid 390 

170.  Tests  of  cements  containing  phosphoric  acid 390 

171.  Composition  of  actual  mixes 394 

172.  Analyses  of  fuel  ash 398 

173.  Change  in  composition  during  burning.  .  .  .  0 397 

174.  Cement  mixture  and  cement,  Sandusky 397 

175.  Fineness  of  raw  mix  at  various  plants „ 425 

176.  Sizes,  power,  etc.,  of  Gates  crushers 433 

177.  Estimated  cost  of  crushing  by  Gates  crusher 433 

178.  Sizes,  power,  etc.,  of  Griffin  mill .  442 


LIST  OF  TABLES.  xxxiii 

PAGE 

179.  Siaps,  weights,  etc.,  of  Gates  ball  mill.  ..,..., 454 

180.  Analyses  of  flint  pebbles 465 

181.  "  "  high-alumina  clays  used  for  kiln  brick. 491 

182.  "  "      "  "      fire-brick  for  kilns 491 

183.  "  "  low-alumina  clays  used  for  kiln  brick 492 

184.  "  "  low-alumina  brick,  furnished  as  kiln  brick 492 

185.  Actual  output  and  fuel  consumption  at  various  plants 495 

183.  Average    "         "      "  "  "  Portland-cement  plants 495 

187.  Heat  used  in  evaporation  of  water •. .   498 

188.  ll      "    "  dissociation  of  carbonates  per  bbl.  cement.  „ 500 

189.  Theoretical  heat  requirements  in  B.T.U.  per  bbl 501 

190.  Utilization  and  losses  of  heat  in  rotary  kilns .......  502 

191.  Newberry's  estimates  on  heat  distribution  in  kilns 505 

192.  Summary  of  Richards"  tests  of  rotary  kilns 507 

193.  Tests  and  estimates  of  heat  distribution,  B.T.U.  per  bbl 509 

194.  Analyses  of  kiln  coals 513 

195.  "         ' l  natural  gas,  Kansas. 523 

196.  Thermal  values  of  natural  gas 523 

197.  Effect  of  form  of  sulphate  used 537 

198.  "  "  adding  various  percentages  of  calcined  plasters 540 

199.  "  "  calcined  sulphate  on  set  of  cement 541 

200.  "  "  gypsum  on  setting-time ;',  541 

201.  "  "  calcium  sulphate  on  strength  of  cement. 543 

202  tt  ttn               ti        «         «        «        «                                               _  544 

203.  "      "  treatment  with  anhydrous  calcium  sulphate 544 

204.  "     ' "  "  li  crude  gypsum 544 

205.  ' '      "  "  "  plaster  of  Paris 544 

206.  Analysis  of  gypsum  used  in  cement-plants 545 

207.  ' '         "  calcined  plaster  used  in  cement-plants 545 

208.  Effect  of  various  salts  on  set  of  cement 546 

209.  Capacity  of  Portland-cement  barrels,  and  weight  of  contents 552-553 

210.  Labor  costs  in  cement-plant ' 558 

211.  "       and  output  in  typical  plants 559 

212.  Costs  of  cement  manufacture  at  Atlas  plant. 559 

213.  Detailed  estimates  of  costs  of  cement  manufacture 560 

214.  Approximate  cost  of  two-kiln  plant 560 

215.  Estimates  of  average  cost  of  Portland-cement  manufacture 561 

216.  Total  production  of  Portland  cement  in  U.  S 562 

217.  Production  of  P.  C.  in  the  U.  S.  in  1901,  1902,  and  1903,  by  States 563 

218.  Portland-cement  production  of  Lehigh  district,  1890-1903 564 

219.  Imports  of  hydraulic  cement  into  the  U.  S.,  1899-1903,  by  countries 564 

220.  Analyses  of  Portland  cement,  1849-1873 575 

221.  "         "  American  Portland  cement 577 

222.  Fineness  of  various  American  Portlands 585 

223.  Compressive  strength  of  Portland-cement  cubes 589 

224  "  f(         ll  "       mortar  and  concrete  cubes 590 

225.  Relation  of  tensile  to  compressive  strength 591 

226.  Modulus  of  elasticity  of  Portland  cement 592 


xxxiv  LIST  OF  TABLES. 

PAGE 

227.  Comparative  tests  of  Portland  cement  and  sand-cement.  ............  ,T  .   594 

228.  Tensile  and  compressive  strength  of  ' '       0  „ 594 

229.  Compressive  strength  of  silica-cement  cubes 590 

230.  ' '  sand-cement  mortars . .  .  .   597 

231.  Modulus  of  elasticity  of  sand  cement .597 

232.  Effect  of  heating  on  compressive  strength 598 

233.  "      "  alumina 603 

234.  Analyses  of  pozzuolana  from-Italy.  .  .. .  .^ 633 

235.  ' '         ' '  ' '  li     France.  . .  • C3 1 

236.  "  :      "  "  "     the  Azores '..,'....   635 

237.  "         "  trass  and  related  materials  from  Germany.  .... .........    636 

238.  ' '  santorin  ash,  from  Santorin.  . K .  i ............    636 

239.  "         "  arSnes,  France . .  .   637 

240.  Strength  of  basaltic  dust :."....' 637 

241.  Average  analyses  of  natural  pozzuolanic  materials.  .  ......,..;. ^. ......   638 

242.  Strength  of  lime — burnt-clay  mortars 639 

243.  Analyses  of  slags  used  for  slag-cement 643 

244.  Strength  of  granulated  and  ungranulated  slag. .  .v. ......   648 

245.  Working  results  of  Ruggles-Coles  drier 651 

246.  Analyses  of  limes  used  in  American  slag-cement  plants 1 ..........   654 

247.  Costs  of  slag-cement  manufacture,  per  barrel. ............ .s,  „....„„„...   664 

248.  Slag-cement  production  in  U.  S.,  1899-1904. •-. ..........   664 

249.  Analyses  of  American  slag-cements „ .  „  ......   667 

250.  "  European    "          "       .......... .668 

251.  Tensile  and  compressive  strength  of  slag-cements. .................   671 

252.  Crushing  strength  of  indurated  slag-bricks 683 

253.  Porosity  of  slag-bricks 683 

254.  Anatyses  of  slag  used  for  slag-blocks .«**;, 689 


CEMENTS,  LIMES,  AND  PLASTERS. 


INTRODUCTION. 


FEW  economic  movements,  during  the  past  decade,  have  equaled 
in  importance  or  interest  the  marvelous  growth  of  the  industries  based 
on  the  non-metallic  structural  materials.  In  this  group  are  included 
the  stone  used  for  building  purposes,  such  clay  products  as  are  used 
in  engineering,  and,  last  in  order  but  not  in  importance,  the  cementing 
materials.  The  production  of  structural  materials  in  the  United  States 
for  the  years  1902-1903  has  been  summarized  in  the  following  table, 
for  convenience  of  reference. 

TABLE  1. 
PRODUCTION  OF  STRUCTURAL  MATERIALS,  1902-1903. 


1902. 

1903. 

Building  stone  

$36  486  392 

$36  052  376 

Brick,  tile,  etc     

98  042  078 

105  526  596 

Cementing  materials      

36,849,943 

45  607  436 

Total,  structural  materials.  . 

$171,378,413 

$192,186,408 

Of  the  three  subgroups  of  materials  quoted  in  the  above  table,  the 
third — cementing  materials — is  the  subject  of  the  present  volume.  It 
will  therefore  be  of  advantage  to  consider  the  financial  statistics  of 
this  subgroup  in  somewhat  more  detail.  The  following  table  (Table  2) 
gives  the  value  of  the  production  in  the  United  States,  for  the  years 
1900-1903  inclusive,  of  the  six  classes  into  which  the  cementing  materials 
may  conveniently  be  divided.  On  later  pages,  where  these  classes  are 
separately  discussed,  much  more  detailed  statistics  are  given  in  regard 
to  eacli  product. 


CEMENTS,  LIMES,  AND  PLASTERS. 


TABLE  2. 
VALUE  OF  CEMENTING  MATERIALS  PRODUCED  IN  THE  UNITED  STATES,  1900-190$ 


1900. 

1901. 

1902. 

1903. 

Plaster  of  Paris,  wall-plaster, 
etc        

$1,500,270 

$1,325,517 

$1,889,190 

$3,550,390 

Lime                    

6,970,062 

8,597,030 

9,573,011 

10,105  190 

Misrnesia  and  magnesite 

.     19,333 

43,057 

21  362 

20  515 

Natural  cement                  . 

3,728,848 

''3,056,278 

4,076,630 

3  675  520 

Portland  cement          

9,280,525 

12,532,360 

20,864,078 

27  713  319 

Slag  cement        >  

274,208 

198,151 

425,672 

542  502 

Total,  cementing  materials 

?21,  773,246 

$25,752,393 

$36,849,943 

$45,607,436 

It  will  be  seen  that  the  value  of  the  entire  group  has  more  than 
doubled  in  these  four  years.  Examination  of  the  figures  for  each  sub- 
group will  show  that  this  increase  was  by  no  means  equally  distributed. 
The  production  of  Portland  cement  almost  tripled  in  value  from  1900 
to  1903;  the  values  of  the  plaster  and  slag-cement  production  about 
doubled;  while  lime  increased  only  50  per  cent,  and  magnesia  and  the 
natural  cements  were  practically  stationary. 

The  great  advance  in  value  of  the  cementing  materials,  taken  as  a 
group,  has  been  steady  and  natural.  Similar  increases  can  therefore  be 
reasonably  expected  to  occur  in  future  years.  Individual  years,  however, 
may  give  less  encouraging  results;  because  any  general  business  depres- 
sion reacts  sharply  upon  building  industries  first  of  all. 

Classification  and  Relationships  of  Cementing  Materials. 

It  seems  desirab]e,  before  taking  up  the  various  classes  of  cement 
materials  individually,  to  devote  an  introductory  section  to  the  con- 
sideration of  the  entire  group  of  cementing  materials,  and  to  attempt 
to  indicate  briefly  the  relationships  that  exist  between  the  different 
classes  which  compose  this  group. 

These  relationships,  as  regards  both  resemblances  and  differences, 
seem  to  be  best  brought  out  by  the  scheme  of  classification  presented 
below.  This  classification  was  fiist  published  by  the  writer  in  1902,* 
in  a  form  differing  but  slightly  from  that  here  given.  It  is  based 
primarily  upon  the  amount  of  chemical  change  caused  by  the  processes 
of  manufacture  and  use;  and  secondarily  upon  the  chemical  composi- 
tion of  the  cementing  material  after  setting.  As  regard  is  paid  to  both 
technologic  and  commercial  considerations,  it  would  seem  to  furnish  a 
fairly  satisfactory  working  classification. 

*  Eckel,  E.  C.     The  classification  of  the  crystalline  cements.     American  Geol- 
ogist, vol.  29,  pp.  146-154.     March,  1902. 


INTRODUCTION.  3 

CLASSIFICATION  OF  CEMENTING  MATERIALS. 

GROUP  I.  SIMPLE  CEMENTING  MATERIALS:  including  all  those  cementing  ma- 
terials which  are  produced  by  the  expulsion  of  a  liquid  or  gas,  through 
the  action  of  heat,  from  a  natural  raw  material,  and  whose  setting 
properties  are  due  to  the  simple  reabsorption  of  the  same  liquid  or 
gas,  and  the  reassumption  of  original  composition;  the  set  cement 
being,  therefore,  similar  in  chemical  composition  to  the  raw  material 
from  which  it  was  derived. 

SUBGROUP  I  a.  HYDRATE  CEMENTING  MATERIALS  OR  PLASTERS:  manufac- 
tured by  driving  off  water  from  gypsum;  setting  properties  due  to  the 
reabsorption  of  water. 

SUBGROUP  I  b.  CARBONATE  CEMENTING  MATERIALS  OR  LIMES  AND  MAGNESIA: 
manufactured  by  driving  off  carbon  dioxide  from  limestone  or  mag- 
nesite;  setting  properties  due  to  the  reabsorption  of  carbon  dioxide. 
GROUP  II.  COMPLEX  CEMENTING  MATERIALS:  including  all  those  cementing 
materials  whose  setting  properties  are  due  to  the  formation  of  entirely 
new  chemical  compounds  during  manufacture  or  use;  the  set  cement 
being,  therefore,  different  in  chemical  composition  from  the  raw  mate- 
rial or  mixture  of  raw  materials  from  which  it  was  derived. 

SUBGROUP  II  a.  SILICATE  CEMENTING  MATERIALS  OR  HYDRAULIC  CEMENTS  : 
setting  properties  due  entirely  or  largely  to  the  formation  of  silicates 
during  the  processes  of  manufacture  or  use. 

SUBGROUP  II  b.  OXYCHLORIDE  CEMENTING  MATERIALS  :    setting  properties 
due  to  the  formation  of  oxychlorides. 

The  various  groups  and  subgroups  above  noted  will  now  be  taken 
up  separately  and  briefly  described,  in  order  that  the  principles  on 
which  the  classification  is  based  may  be  clearly  understood. 

Group  I.    Simpla  Cementing  Materials. 

The  products  included  in  the  present  group  include  those  known 
as  " plasters",  "hard-finish  cements",  "limes",  and  "magnesia." 

The  material  from  which  the  "plasters"  and  "hard-finish  cements" 
are  derived  is  gypsum,  a  hydrous  calcium  sulphate;  while  the  limes 
are  derived  from  limestone,  which  is  essentially  calcium  carbonate,  though 
usually  accompanied  by  greater  or  less  amounts  of  magnesium  car- 
bonate; and  magnesia  is  derived  from  more  or  less  pure  magnesite,  a 
natural  magnesium  carbonate. 

On  heating  gypsum  to  a  certain  temperature,  the  raw  material  parts 
readily  with  much  of  its  water,  leaving  an  almost  anhydrous  calcium 
sulphate,  known  commercially  as  plaster  of  Paris.  On  exposing  this 
plaster  to  water,  it  rehydrates,  and  again  takes  the  composition  of 
the  gypsum  from  which  it  was  derived. 


4  CEMENTS,  LIMES,  AND  PLASTERS. 

In  like  manner  limestone,  on  being  sufficiently  heated,  gives  off 
Its  carbon  dioxide,  leaving  calcium  oxide,  or  "quicklime".  This,  on 
exposure  to  moisture  and  air  carrying  carbon  dioxide,  reabsorbs  carbon 
dioxide  and  reassumes  its  original  composition — calcium  carbonate. 
Magnesite,  on  being  heated,  loses  its  carbon  dioxide,  leaving  magnesium 
oxide,  or  magnesia.  This,  under  normal  conditions  of  burning,  will 
reabsorb  carbon  dioxide,  and  set  in  its  original  form  as  magnesium 
carbonate.  i* 

The  cementing  materials  included  in  this  group,  therefore,  while 
differing  in  composition  and  properties,  agree  in  certain  important 
points.  They  are  all  manufactured  by  heating  a  natural  raw  material 
sufficiently  to  remove  much  or  all  of  its  water  or  carbon  dioxide;  and, 
in  all,  the  setting  properties  of  the  cementing  material  are  due  to  the 
fact  that,  on  exposure  to  the  water  or  carbon  dioxide  which  has  thus 
been  driven  off,  the  cement  reabsorbs  the  previously  expelled  liquid  or 
gas,  and  reassumes  the  chemical  composition  of  the  raw  material  from 
which  it  was  derived.  Plaster  of  Paris,  after  setting,  is  not  chemically 
different  from  the  gypsum  from  which  it  was  derived;  while  if  the 
sand,  added  simply  to  avoid  shrinkage,  be  disregarded,  a  thoroughly 
hardened  lime  mortar  is  nothing  more  or  less  than  an  artificial  lime- 
stone. 

The  principal  points  of  difference  between  the  two  subgroups — the 
plasters  and  the  limes — may  be  briefly  noted  as  follows : 

Subgroup  I  a.  Hydrate  cementing  material :  plasters. — The  materials 
here  included  are  known  in  commerce  as  " plaster  of  Paris",  " cement 
plaster",  " Keene's  cement",  " Parian  cement",  etc.  All  of  these  hydrate 
cements  or  plasters  are  based  upon  one  raw  material — gypsum.  The 
partial  dehydration  of  pure  gypsum  produces  plaster  of  Paris.  By 
the  addition  to  gypsum,  either  by  nature  or  during  manufacture,  of 
relatively  small  amounts  of  other  materials,  or  by  slight  variations 
in  the  processes  of  manufacture,  the  time  of  setting,  hardness,  and  other 
important  technical  properties  of  the  resulting  plaster  can  be  changed 
to  a  degree  sufficient  to  warrant  separate  naming  and  descriptions  of 
the  products. 

Both  the  technology  and  the  chemistry  of  the  processes  involved 
in  the  manufacture  of  the  hydrate  cements  are  simple.  The  mineral 
gypsum,  when  pure,  is  a  hydrous  sulphate  of  lime,  of  the  formula 
CaSO4,2H2O,  corresponding  to  the  composition:  calcium  sulphate  79.1%, 
water  20.9%.  As  noted  later  (under  the  head  of  Cement  Plasters)  gyp- 
sum,  as  mined,  rarely  even  approximates  to  this  ideal  composition,  its  im- 
purities often  amounting  to  25%  or  even  more.  These  impurities,  chiefly 


INTRODUCTION.  *  5 

clayey  materials  and  fragments  of  quartz  and  limestone,  often  exercise 
an  appreciable  effect  upon  the  properties  of  the  plaster  resulting  from 
burning  such  impure  gypsum.  On  burning  gypsum  at  a  relatively 
low  temperature  (350°-400°  F.)  much  of  its  water  of  combination  is 
driven  off,  leaving  a  partially  dehydrated  calcium  sulphate.  This, 
when  ground,  is  plaster  of  Paris,  or  if  it  either  naturally  or  artificially 
contains  certain  impurities,  it  is  called  "cement  plaster".  When  either 
plaster  of  Paris  or  cement  plaster  is  mixed  with  water,  the  percentage 
of  water  which  was  driven  off  during  calcination  is  reabsorbed,  and 
the  mixture  hardens,  having  again  become  a  hydrous  sulphate  'of  lime. 
The  processes  involved  in  the  manufacture  and  setting  of  the  dead- 
burned  plasters  and  hard-finish  plasters  are  slightly  more  complicated, 
but  the  reactions  involved  are  of  the  same  general  type.' 

Subgroup  I  b.  Carbonate  cementing  materials :  limes  and  magnesia. 
— The  cementing  materials  falling  in  the  present  subgroup  are  oxides 
derived  from  natural  carbonates  by  the  application  of  heat.  On  exposure, 
under  proper  conditions,  to  any  source  of  carbon  dioxide,  the  cement- 
ing material  recarbonates  and  "sets".  In  practice  the  carbon  dioxide 
required  for  setting  is  obtained  simply  by  exposure  of  the  mortar  to 
the  air.  In  consequence  the  set  of  these  carbonate  cements,  as  com- 
monly used,  is  very  slow  (owing  to  the. small  amount  of  carbon  dioxide 
which  can  be  taken  up  from  ordinary  air) ;  and,  what  is  more  important 
from  an  engineering  point  of  view,  none  of  the  mortar  in  the  interior 
of  a  wall  ever  acquires  hardness,  as  only  the  exposed  portions  have  an 
opportunity  to  absorb,, carbon  dioxide.  From  the  examination  of  old 
mortars  it  has  been  thought  probable  that  a  certain  amount  of  chemical 
action  takes  place  between  the  sand  and  the  lime,  resulting  in  the  forma- 
tion of  lime  silicates ;  but  this  effect  is  slight  and  of  little  engineering 
importance  compared  with  the  hardening  which  occurs  in  consequence 
of  the  reabsorption  of  carbon  dioxide  from  the  air. 

Limestone  is  the  natural  ?  raw  material  whose  calcination  furnishes 
most  of  the  cementing  materials  of  this  group.*  If  the  limestone  be 
an  almost  pure  calcium  carbonate,  it  will,  on  calcination,  yield  calcium 
oxide,  or  "quicklime".  If,  however,  the  limestone  should  contain 
any  appreciable  percentage  of  magnesium  carbonate,  the  product  will 
be  a  mixture  of  the  oxides  of  calcium  and  magnesium,  commercially 
known  as  a  magnesian  lime.  A  brief  sketch  of  the  mineralogic  re- 
lationships of  the  various  kinds  of  limestone,  in  connection  with  the 

*  The  subject  of  magnesia  as  a  cementing  material,  being  too  complicated  for 
brief  discussion,  will  not  be  taken,  up  here.     See  Chapters  XI  and  XII. 


6  CEMENTS,  LIMES,  AND  PLASTERS. 

chemistry  of  lime-burning,  will  be  of  service  at  this  point  of   the   dis- 
cussion. 

Pure  limestone  has  the  composition  of  the  mineral  calcite,  whose 
formula  is  CaCO3,  corresponding  to  the  composition:  calcium  oxide  56%, 
carbon  dioxide  44%.  In  the  magnesian  limestones  part  of  this  calcium 
carbonate  is  replaced  by  magnesium  carbonate,  the  resulting  rock  there- 
fore having  a  formula  of  the  type  XCaC03,YMgCO3.  This  replacement 
may  reach  the  point  at  which  the  rock  ffas  the  composition  of  the  mineral 
dolomite — an  equal  mixture  of  the  two  carbonates,  with  the  formula 
CaC03,MgCO3,  corresponding  to  the  composition:  calcium  oxide  30.44%, 
magnesium  oxide  21.73%,  carbon  dioxide  47.83% /'  Limestones  may 
therefore  occur  with  any  intermediate  amount  of  magnesium  carbonate, 
and  the  lime  which  they  produce  on  calcination  will  carry  correspond- 
ing percentages  of  magnesium  oxide,  from  0%  to  41.65%.  Commer- 
cially those  limes  which  carry  less  than  10%  of  magnesium  oxide  are, 
for  building  purposes,  marketable  as  "pure  limes";  while  those  carry- 
ing more  than  that  percentage  will  show  sufficiently  different  properties 
to  necessitate  being  marketed  as  "magnesian  limes". 

Aside  from  the  question  of  magnesia,  a  limestone  may  contain  a 
greater  or  lesser  amount  oforeal  impurities.  Of  these  the  most  impor- 
tant are  silica  (SiC>2) ,"  alumina  (A1203).  and  iron  oxide  (Fe2O3).  These 
impurities,  if  present  in  sufficient  quantity,  will  materially  affect  the 
properties  of  the  lime  produced,  as  will  be  noted  later  under  the  heads 
of  Hydraulic  Limes  and  Natural  Cements. 

The  limes  may  be  divided  into  two  classes: 

(1)  High-calcium  limes; 

(2)  Magnesian  limes. 

High-calcium  limes. — On  heating  a  relatively  pure  carbonate  of  lime 
to  a  sufficiently  high  degree,  its  carbon  dioxide  is  driven  off,  leaving 
calcium  oxide  (CaO),  or  "quicklime".  Under  ordinary  conditions, 
the  expulsion  of  the  carbon  dioxide  is  not  perfectly  effected  until  a 
temperature  of  925°  C.  is  reached.  The  process  is  greatly  facilitated 
by  blowing  air  through  the  kiln,  or  by  the  injection  of  steam.  On 
treating  quicklime  with  water,  "slaking"  occurs, -'heat  being  given  off, 
and  the  hydrated  calcium  oxide  (CaH2O2)  being  formed.  The  hydrated 
oxide  (slaked  lime)  will,  upon  exposure  to  the  atmosphere,  slowly  reabsorb 
sufficient  carbon  dioxide  to  reassume  its  original  composition  as  lime  car- 
bonate. As  this  reabsorption  can  take  place  only  at  points  where  the 
mortar  is  exposed  to  the  air,  the  material  in  the  middle  of  thick  walls 
never  becomes  recarbonated.  In  order  to  counteract  the  shrinkage  which 
would  otherwise  take  place  during  the  drying  of  the  mortar,  sand  is 


INTRODUCTION.  7 

invariably  added  in  the  preparation  of  lime  mortars,  and,  as  noted  above, 
it  is  possible  that  certain  reactions  take  place  between  the  lime  and  the 
sand.  Such  reactions,  however,  though  possibly  contributing  some- 
what to  the  hardness  of  old  mortars,  are  only  incidental  and  subsidiary 
to  the  principal  cause  of  setting — recarbonation.  The  presence  of 
impurities  in  the  original  limestone  affects  the  character  and  value  of 
the  lime  produced.  Of  these  impurities,  the  presence  of  silica  and 
alumina  in  sufficient  quantities  will  give  hydraulic  properties  to  the 
resulting  limes;  such  materials  will  be  discussed  in  the  next  group  as 
Hydraulic  Limes  and  Natural  Cements. 

Magnesian  limes. — The  presence  of  any  considerable  amount  of 
magnesium  carbonate  in  the  limestone  from  which  a  lime  is  obtained 
has  a  noticeable  effect  upon  the  character  of  the  product.  If  burned 
at  the  temperature  usual  for  a  pure  limestone,  magnesian  limestones 
give  a  lime  which  slakes  slowly  without  evolving  much  heat,  expands 
less  in  slaking,  and  sets  more  rapidly,  than  pure  lime.  To  this  class 
belong  the  well-known  and  much-used  limes  of  Canaan  (Conn, ) ;  Tuck- 
ahoe,  Pleasantville,  and  Ossining  (N.  Y.) ;  various  localities  in  New  Jersey 
and  Ohio;  and  Cedar  Hollow  (Penn.).  Under  certain  conditions  of 
burning,  pure  magnesian  limestones  yield  hydraulic  products,  but  in 
this  case,  as  in  the  case  of  the  product  obtained  by  burning  pure  mag- 
nesite,  the  set  seems  to  be  due  in  part  at  least  to  the  formation  of  a 
hydroxide  rather  than  of  a  carbonate.  Magnesian  limestones  carrying 
sufficient  silica  and  alumina  will  give,  on  burning,  a  hydraulic  cement 
falling  in  the  next  group  under  the  head  of  Natural  Cements. 


Group  II.  Complex  Cementing  Materials. 

The  cementing  materials  grouped  here  as  Complex  Cements  include 
all  those  materials  whose  setting  properties  are  due  to  the  formation  of 
new  compounds,  during  manufacture  or  use,  and  not  to  the  mere  reas- 
sumption  of  the  original  composition  of  the  material  from  which  the 
cement  was  made.  These  new  compounds  may  be  formed  either  by 
chemical  change  during  manufacture  or  by  chemical  interaction,  in 
use,  of  materials  which  have  merely  been  mechanically  mixed  during 
manyfacture. 

Subgroup  II  a.  Silicate  cementing  materials :  hydraulic  cements. — 
In  the  class  of  silicate  cements  are  included  all  the  materials  commonly 
known  as  cements  by  the  engineer  (natural  cements,  Portland  cement, 
puzzolan  cements),  together  with  the  hydraulic  limes. 

Though  differing  widely  in  raw  materials,  methods  of  manufacture, 


£  CEMENTS,  LIMES,  AND  PLASTERS. 

and  properties,  the  silicate  cements  agree  in  two  prominent  features: 
they  are  all  hydraulic  (though  in  very  different  degrees);  and  this 
property  of  hydraulicity  is,  in  all,  due  largely  or  entirely  to  the  formation 
of  tricalcic  silicate  (3CaO,SiC>2).  Other  silicates  of  lime,  as  well  as 
silico  aluminates,  may  also  be  formed;  but  they  are  relatively  unim- 
portant, except  in  certain  of  the  natural  dements  and  hydraulic  limes, 
where  the  lime  aluminates  may  be  of  greater  importance  than  is  here 
indicated.  This  will  be  recurred  tortn  discussing  the  groups  named. 

The  silicate  cements  are  divisible,  on  technologic  grounds,  into  four 
distinct  classes.  The  basis  for  this  division  is  given  below.  It  will 
be  seen  that  the  last  named  of  these  classes  (ttte  puzzolan  cements) 
differs  from  the  other  three  very  markedly,  inasmuch  as  its  raw  materials 
are  not  calcined  after  mixture;  while  in  the  last  three  classes  the  raw 
materials  are  invariably  calcined  after  mixture.  The  four  classes  differ 
somewhat  in  composition,  but  more  markedly  in  methods  of  manu- 
facture and  in  the  properties  of  the  finished  cements. 

CLASSES   OF    HYDRAULIC   CEMENTS. 

1.  Hydraulic  limes  are  produced  by  burning,  at  relatively  low  tem- 
peratures, a  natural  siliceous  limestone  which  carries  so  much  lime  car- 
bonate, compared  to  its  content  of  silica  and  alumina,  that  the  burned 
product  will  contain  a  considerable  amount  of  free  lime  (CaO)  in  addi- 
tion to  the  silicates  and  aluminates  of  lime  that  have  been  formed. 
In  consequence  of  the  relatively  large  percentage  of  free  lime,  the  burned 
masses  will  slake  if  water  be  poured  on  them,  but  because  much  of 
them  is  composed  of  silicates  and  aluminates  of  lime,  they  will  slake 
very  slowly  and  their  final  product  will  have  hydraulic  properties. 

The  hydraulic  limes  are  thus  intermediate  in  composition,  methods 
of  manufacture,  and  properties  between  the  true  limes  and  the  cements 
proper. 

2.  Natural  cements  are  produced  by  burning  a  natural  clayey  lime- 
stone, containing  from  15  to  40  per  cent  of  silica,  alumina,  and  iron 
oxide.     This  burning  takes  place  at  a  temperature  that  is  usually  little 
if  any  above  that  of  an  orolinary  lime-kiln.     During  the  burning  the 
carbon  dioxide  of  the  limestone  is  almost  entirely  driven  off,  and  the 
lime  combines  with  the  silica,  alumina,  and  iron  oxide,  forming  a  mass 
containing  silicates,  aluminates,  and  ferrites  of  lime.     In  case  the  original 
limestone  contained  much  magnesium  carbonate,  the  burned  rock  will 
contain  a  corresponding  amount  of  magnesia  and  magnesian  compounds. 

After  burning,  the  burned  mass  will  not  slake  if  water  be  poured 
on  it.  It  is  necessary,  therefore,  to  grind  it  quite  fine,  after  which,  if 


INTRODUCTION.  9 

the  resulting  powder  (natural  cement)  be  mixed  with  water,  it  will 
harden  rapidly.  This  hardening  or  setting 'will  also  take  place  under 
water. 

3.  Portland  cement  is  produced  by  burning  a  finely  ground  artificial 
mixture  containing  essentially  lime,  silica,  alumina,  and  iron  oxide,  in 
certain   definite   proportions.     Usually    this    combination   is   made   by 
mixing  limestone,  chalk,  or  marl  with  clay  or  shale,  in  which  case  about 
three  times  as  much  of  lime  carbonate  as  of  clayey  materials  should  be 
present  in  the  mixture.     The  burnirfg  of  this  mixture  takes  place  at  a 
high  temperature,  approaching  3000°  F.,  and  must  therefore  be  carried 
on  in  kilns  of  special  design  and  lining.     During  the  burning,   com- 
bination of  the  lime  with  the  silica,  alumina,  and  iron  oxide  takes  place. 
The  product  of  the  burning  is  a  semifused  mass  called  " clinker",  and 
consists  of  silicates,  aluminates,  and  ferrites  of  lime,  each  being  present 
in  certain  fairly  definite  proportions.     This  "clinker"  must  be  finely 
ground.     After  such  grinding  the  resulting  powder,  which  is  then  Port- 
land cement,  will  harden  under  water. 

Portland  cement  is  blue  to  gray  in  color,  with  a  specific  gravity  of 
3.0  to  3.2.  It  sets  more  slowly  than  natural  cements,  but  soon  attains 
a  higher  tensile  strength. 

4.  Puzzclan    cements. — Certain    natural     and    artificial   products, 
such  as  some  volcanic  ashes  and  blast-furnace  slags,  will  show  feeble 
hydraulic    properties   if   finely  pulverized.     Their  hydraulicity  is  very 
markedly  increased  if  their  powder,   instead  of  being  used  alone,   is 
mixed  with  powdered  slaked  lime.     Such  mixtures  of  slaked  lime  with 
a  relatively  feeble  hydraulic   agent  are  known  as  Puzzolan  Cements. 
The   puzzolan   cements   are   therefore   simply   mechanical   mixtures   of 
the  two  ingredients,  as  the  mixture  is  not  burned  at  any  stage  of  the 
process. 

Puzzolan  cements  are  usually  light  bluish  in  color,  and  of  lower 
specific  gravity  and  less  tensile  strength  than  Portland  cement.  They 
are  better  adapted  to  use  under  water  than  to  use  in  air,  as  is  explained 
later  in  this  volume 

Subgroup  II  b.  Oxychloride  cements. — In  1853  the  chemist  Sorel 
discovered  the  fact  that  zinc  chloride  mixed  with  zinc  oxide  united 
with  it  to  form  a  very  hard  cement.  Later  it  was  found  that  a  solution 
of  magnesium  chloride  will  unite,  in  the  same  manner,  with  magnesia. 
The  product  is,  in  both  cases,  an  oxy chloride — of  zinc  or  magnesium  as 
the  case  may  be. 

It  is  obvious  that  cementing  materials  of  this  character  cannot 
well  be  placed  on  the  market  as  structural  cements,  but  the  property 


10  CEMENTS,  LIMES,  AND  PLASTERS. 

above  noted  has  been  taken  advantage  of  in  the  manufacture  of  a  number 
of  patented  artificial  stones,  the  exact  methods  followed  depending 
upon  the  particular  process  that  is  used.  The  best  known  of  these 
artificial  stones  is  probably  "Sorel-stone",  which  is  frequently  alluded 
to  in  engineering  text-books.  As  the  subject  of  oxy chloride  cements 
is  intimately  connected  with  that  of  magnesia  cements,  the  two  will 
be  discussed  together  in  Chapters  XI  to  XII. 

The  following  table  shows  the  Delation  of  the  various  cementing 
materials  which  have  been  briefly  discussed  in  this  chapter.  For  con- 
venience of  reference,  the  pages  on  which  the  different  products  are 
described  in  detail  have  been  added. 

f  Plaster  of  Paris 1  31-67 

Hydrate    cements    or  I  Cement  plasters J  ' 

plasters )  Hard-finish  plasters 76-78 

Simple  cements.  .v'J  l  Dead-burnt  plasters. . ; 68-76 


Carbonate  cements  or 


limes 


Complex  cements . 


Silicate  cements. 


[  Magnesia 148-167 

{  Hydraulic  lime 168-193 

]  Natural  cements 194-293 

I  Portland  cement 294-631 

[  Puzzolan  cements 632-689 


Oxychloride  cements.    {  Sorel-stone,  etc 162-167 


Chemical   and  Physical   Data   Employed  in   the   Discussion   of 
Cementing  Materials. 

In  the  course  of  the  discussion  it  will  frequently  be  necessary  to 
use  certain  chemical  and  physical  data,  such  as  atomic  weights,  values 
of  various  heat-units,  etc.  These  are  to  be  found  in  most  engineering 
pocket-books,  but  for  convenience  of  reference  the  more  important 
data  have  been  placed  in  the  present  chapter. 

Atomic  weights  of  elements. — In  the  following  table  (Table  3)  are 
given  the  names,  symbols,  and  atomic  weights  of  all  the  chemical  ele- 
ments.* The  first  column  of  this  table  contains  the  name  of  each 
element;  the  second,  its  chemical  symbol  or  abbreviation;  the  third, 
its  atomic  weight  calculated  on  the  basis  of  the  atomic  weight  of  oxygen 
being  16;  the  fourth,  its  atomic  weight  on  the  basis  of  the  atomic  weight 
of  hydrogen  being  1. 

In  use,  it  is  a  matter  of  absolute  indifference  whether  the  figures  in 

*  Through  the  courtesy  of  Prof.  F.  W.  Clarke  the  writer  is  enabled  to  present 
this  table,  which  contains  the  corrections  for  1905. 


INTRODUCTION. 


11 


the  third  column  or  those  in  the  fourth  are  employed:  but  of  course 
the  selection  should  be  consistent  throughout.  Chemists  are  about 
equally  divided  as  to  the  use  of  the  two  series.  For  many  purposes  the 
O  =  16  basis  is  the  more  convenient,  as  it  gives  even  figures  for  several 
common  elements. 

Such  elements  as  enter  into  the  calculation  of  cement,  plaster,  lime, 
fuel,  or  slag  are  given  in  black-faced  type  for  convenience  of  reference. 

TABLE  3. 
ATOMIC  WEIGHTS  OF  ELEMENTS. 


Name  of  Element. 

Sym- 
bol. 

Atomic  Weight. 

Name  of  Element. 

Sym- 
bol. 

Atomic  Weight. 

O  =  16. 

H  =  l. 

O  =  16. 

H  =  l. 

Aluminum  

Al 
Sb 
A 
As 
Ba 
Bi 
B 
Br 
Cd 
Cs 
Ca 
C 
Ce 
Cl 
Cr 
Co 
Cb 
Cu 
Er 
F 
Gd 
Ga 
Ge.  . 
Gl 
Au 
He 
H 
In 
I 
Ir 
Fe 
Kr 
La 
Pb 
Li 
Mg 
Mn 
Hg 
Mo 

27.1 

120.2 
39.9 
75.0 
137.4 
208.5 
11.0 
79.96 
112.4 
132.9 
40.1 

12.  O 

140.25 
35.45 
52.1 
59.0 
94.0 
63.6 
166.0 
19.0 
156.0 
70.0 
72.5 
9.1 
197  =  2 
4.0 
1.008 
115.0 
126.97 
193.0 

55-9 

81.8 
138.9 
206.9 
7.03 
24.36 
55-0 
200.0 
96.0 

26.9 
119.3 
39.6 
74.4 
136.4 
206.9 
10.9 
79.36 
111.6 
131.9 

39-7 
ii  .91 

139.2 
35.18 
51.7 
58.57 
93.3 
63.1 
164.7 
18.9 
154.8 
69.5 
72.0 
9.03 
195.7 
4.0 

I.  000 

114.1 
126.01 
191.5 

55-5 
81.2 
137.9 
205.35 
6.98 
24.18 
54-6 
198.5 
95.3 

Neodymium.  .  .  . 
Neon            . 

Nd 
Ne. 
Ni 
N 
Os 
0 
Pd 
P 
Pt 
K 
Pr 
Ra 
Rh 
Rb 
Ru 
Sm 
Sc 
Se 
Si 
Ag 
Na 
Sr 
S 
Ta 
Te 
Tb 
Tl 
Th 
Tm 
Sn 
Ti 
W 

u 

V 
Xe 
Yb 
Yt 
Zn 
Zr 

143.6 
20.0 
58.7 
14.04 
191.0 
16.00 
106.5 
31-0 
194.8 

39-iS 
140.5 
225.0 
103.0 
85.5 
101.7 
150.3 
44.1 
79.2 
28.4 
107.93 
23  05 
87.6 
32.06 
183.0 
127.6 
160.0 
204.1 
232.5 
171.0 
119.0 
48.1 
184.0 
238.5 
51.2 
128.0 
173.0 
89.0 
65.4 
90.6 

142.5 
19.9 

58.3 

13  93 

189.6 
15-88 
105.7 
30.77 
193.3 
38.85 
139.4 
223.3 
102.2 
84.9 
100.9 
149.2 
43.8 
78.6 
28.2 
107.1 

22.88 

86.94 
31.82 
181.6 
126.6 
158.8 
202.6 
230.8 
169.7 
118.1 
47-7 
182.6 
236.7 
50.8 
127.0 
171.7 
88.3 
64.9 
89.9 

Arsron 

Nickel 

Arsenic 

Nitrogen  

Barium.  ...  .... 

Osmium  

Bismuth. 

Oxygen  

Boron     

Palladium  
Phosphorus.     .  .  . 

Bromine 

Cadmium           .  . 

Platinum.  „  
Potassium.  ..... 
Praseodymium.  . 
Radium  

Cspsium            o  .  . 

Calcium         .... 

Carbon  

Cerium         ..... 

Rhodium  

Chlorine         .... 

Rubidium  

Chromium  

Ruthenium.  .... 
Samarium  

Cobalt        

Columb  ium 

Scandium  
Selenium  
Silicon  
Silver  
Sodium  

Copper  . 

Erbium 

Fluorine 

Gadolinium  
Gallium 

Strontium  
Sulphur  
Tantalum  

Germanium.  .... 
Glucinum 

Gold 

Tellurium  

Helium 

Terbium     

Hvdrosfen.  •. 

Thallium    

uyuiugcii.  ...... 

Indium.  
Iodine  
Iridium   

Thorium  

Thulium  

Tin    

Iron  

Titanium  
Tungsten 

Krypton 

Lanthanum  

Uranium  
Vanadium  

Lead 

Lithium  

Xenon        

Ytterbium  

Manganese  
Mercury  

Yttrium  
Zinc.  
Zirconium    

Molybdenum.  .  .  . 

12 


CEMENTS,  LIMES,  AND  PLASTERS. 


Chemical  compounds.  —  Certain  chemical  combinations  will  be 
mentioned  very  frequently  in  the  discussion  of  cementing  materials. 
The  more  important  of  these  compounds  are  listed  in  the  following 
table,  with  their  symbols  and  also  the  name  by  which  they  are  known 
when  they  occur  as  minerals  or  as  commercial  products, 

TABLE.  4. 

•         .  V* 

NAMES  AND  SYMBOLS  OF  PRINCIPAL  COMPOUNDS. 


Symbol. 

Name. 

Mineral  or  Commercial 
Name. 

CaO          

Calcium  oxide  

Lime:  quicklime 

CaCOg    

Calcium,  carbonate  

Calcite 

3CaO  SiO  . 

Tricalcium  silicate 

CaCOg  MgCOg 

Calcium-magnesium  carbonate 

Dolomite 

CaH  O2 

Lime  hydrate 

Slaked  lime 

CaSO4                 .    .    . 

Calcium  sulphate 

Dead-burned  plaster 

CaSO4  +  2H2O   

Hydrous  calcium  sulphate 

Gypsum 

2CaSO4  +  H2O  

Plaster  of  Paris 

MgO 

Magnesium  oxide  

Magnesia 

MgCOo   

Magnesium  carbonate  

Magnesite 

SiO 

Silica  .  . 

Quartz 

Al  O, 

Alumina 

FeO     ' 

Ferrous  oxide* 

Fe9O, 

Ferric  oxide 

Heat-units. — Two  heat-units  are  now  in  common  use — the  British 
and  the  metric. 

The  British  thermal  unit  (  =  B.T.U.)  is  the  quantity  of  heat  required 
to  raise  the  temperature  of  1  Ib.  of  water  one  degree  Fahrenheit  when 
at  the  temperature  of  maximum  density  (  =  39.1°  F.  or  4°  C.). 

The  metric  unit  (  =  calorie)  is  the  quantity  of  heat  required  to  raise 
the  temperature  of  1  kilogram  of  water  one  degree  centigrade  when 
at  the  temperature  of  maximum  density. 

From  these  definitions  the  two  units  may  be  converted  according 
to  the  following  equations : 

1  B.T.U.=    .252  calorie. 
1  calorie  =  3. 968  B.T.U. 
1  calorie  per  kilogram  =1.8  B.T.U  per  poundo 

Metric  conversion  tables. — Since  much  of  the  literature  of  cementing 
materials  is  published  in  French  and  German,  metric  units  are  frequently 
employed.  In  the  present  volume  such  units  have  been  converted 
into  American  units  throughout,  but  for  convenience  a  few  conversion 
tables  are  here  inserted  to  cover  the  more  common  cases. 


INTRODUCTION. 

LENGTH.    * 

1  inch  =   2.54  centimeters. 

1  centimeter  =      .3937  inch. 
1  foot  =      .  3048  meter. 

1  meter          =  39 . 37  inches 

=   3. 2808  feet. 

SURFACE. 

1  square  inch  =   6 . 452  square  centimeters. 

1  square  centimeter  =      .155  square  inch. 
1  square  foot  =      .  0929  square  meter. 

1  square  meter          =  10 . 764  square  feet. 

VOLUME. 

1  cubic  inch  =  16 . 387  cubic  centimeters. 

1  cubic  centimeter  =      .061  cubic  inch. 
1  cubic  foot  =      .02832  cubic  meter. 

1  cubic  yard  =      .  7645  cubic  meter. 

1  cubic  meter          =35.314  cubic  feet 

=    1 . 308  cubic  yards. 

WEIGHT. 

1  ounce  avoirdupois  =  28 . 35  grams. 
1  pound  =      .4536  kilogram. 

1  kilogram  =   2 . 2046  pounds. 

CAPACITY. 

1  cubic  foot  =  28. 317  liters. 
1  liter  =61.023  cubic  inches 

=      .03531  cubic  foot. 
1  gallon        =   3. 785  liters. 

PRESSURE. 

1  pound  per  square  inch  =      .  070308  kilogram  per  square  inch. 

1  kilogram  per  square  centimeter  =  14 . 223  pounds  per  square  inch. 


PAKT  I.   PLASTERS. 


CHAPTER  I. 
COMPOSITION,  DISTRIBUTION,  AND  EXCAVATION  OF  GYPSUM. 

THE  mineral  called  gypsum  is  the  raw  material  which  serves  as  the 
basis  for  the  manufacture  of  plaster  of  Paris,  "  cement  plaster",  anc 
the  various  related  types  of  plasters.  In  the  present  chapter  the  com- 
position, properties,  varieties,  mode  of  occurrence,  origin,  and  distribu- 
tion of  gypsum  will  be  described  in  the  order  named,  after  which  th< 
methods  and  costs  of  quarrying  and  mining  gypsum  will  be  discussed 

Chemical  composition.  —  The  mineral  gypsum,  when  absolutely  pure 
is  a  hydrous  sulphate  of  lime,  made  up  of  one  molecule  of  lime  sulphate 
combined  with  two  molecules  of  water.  The  chemical  formula  o 
gypsum  is  therefore  CaSO4+2H2O.  This,  when  reduced  to  percentages 
of  weight,  corresponds  to  the  following: 


n  /rt'orv  .'  i  OTT  r\\      /  Lime  sulphate  (CaSO4)  ......    79.1% 

Gypsum  (CaSO4  +  2H2O)  =  |  Water  (^Q)     ^  .....  «  ......   2Q  g/0 

The  79.1%  of  lime  sulphate  can,  in  turn,  be  considered  as  being  mad< 
up  of  32.6%  of  lime  (CaO),  plus  46.5%  of  sulphur  trioxide  (S03) 
Reduced  to  its  ultimate  components,  the  composition  of  pure  gypsun 
may  therefore  be  represented  as  follows: 

[Lime  (CaO)  ...............     32.6% 

Gypsum  (CaSO4  +  2H2O)  =  ^  Sulphur  trioxide  (SO3)  ......     46.5 

[Water  (H20)  ..............     20.9 

100.0 

Deposits  of  gypsum  large  enough  to  be  worked  for  plaster  are,  how 
ever,  rarely  even  approximately  as  pure  as  this.  Gypsum  as  excavatec 
for  a  plaster-plant  will  usually  carry  varying  and  often  high  percentage 
of  such  impurities  as  clay,  limestone,  magnesian  limestone,  iron  oxide 

14 


_400 600 CuO  mile* 


FIG.  i. 


[To  face  p   14. 


COMPOSITION,  DISTRIBUTION,  AND  EXCAVATION  OF  GYPSUM.      15 

etc.  Table  8,  on  pp.ge  53,  gives  a  number  of  analyses  of  the  gypsum 
used  at  various  plaster-plants;  and  a  glance  at  this  table  will  show 
the  kind  and  amount  of  impurities  which  may  be  expected  to  occur  in 
commercial  gypsum. 

Varieties  of  gypsum. — Owing  to  differences  in  form,  texture,  color, 
etc.,  gypsum  presents  several  varieties,  some  of  which  have  been  given 
distinct  names.  The  ordinary  form  in  which  gypsum  occurs  in  the 
workable  deposits  is  as  massive  or  rock  gypsum.  Alabaster  is  a  pure 
white,  fine-grained  massive  gypsum,  occasionally  used  for  statuary,  etc. 
The  term  selenite  is  applied  to  the  crystalline,  white,  almost  transparent 
gypsum  which  occurs  frequently,  but  in  relatively  small  quantity,  scattered 
through  a  deposit  of  massive  gypsum. 

Aside  from  these  various  forms  of  rock  gypsum,  two  less  massive 
forms  of  the  mineral  are  to  be  noted  as  being  of  commercial  importance. 
In  certain  Western  States  and  Territories  deposits  of  earthy  gypsum,  gyp- 
sum earth,  or  gypsite  occur.  These  deposits  contain  an  impure,  earthy, 
granular  form  of  gypsum.  Deposits  of  gypsum  sands  are  also  found 
in  the  West,  being  dunes  or  heaps  of  fine  grains  of  gypsum. 

Physical  properties. — Pure  gypsum  is  white  and,  when  in  the  crystal- 
line form,  translucent.  The  impurities  which  it  commonly  contains 
usually  destroy  its  translucency  and. affect  its  color,  so  that  the  mineral 
as  mined  is  an  opaque,  fine-grained  mass,  varying  from  white  to  reddish, 
gray,  or  brown  in  color. 

Gypsum  can  be  distinguished  from  most  other  minerals  by  its  extreme 
softness,  for  even  when  in  the  crystalline  form  it  can  be  readily  scratched 
by  the  finger-nail.  When  treated  with  acids  it  does  not  effervesce. 
On  heating  it  loses  its  water  of  crystallization  and,  if  previously  trans- 
lucent, becomes  a  chalky,  opaque  white.  Pure  crystalline  specimens 
have  a  specific  gravity  *  of  2.30  to  2.33. 

Anhydrite. — The  mineral  anhydrite  is  closely  related  to  gypsum, 
as  it  is  an  anhydrous  lime  sulphate,  with  the  formula  CaSO4.  It  there- 
fore corresponds  in  composition  to  the  product  obtained  by  heating 
gypsum  so  strongly  as  to  drive  off  all  of  its  water  of  combination  (see 
pages  31,  32).  Anhydrite  occurs,  but  in  relatively  small  amounts,  in 
almost  all  gypsum  deposits.  Pure  specimens  have  a  specific  gravity* 
of  2.92  to  2.98. 

Occurrence  and  origin  of  gypsum  deposits. — Rock  gypsum  occurs 
in  the  form  of  beds,  frequently  closely  associated  with  beds  of  rock 
salt,  and  almost  always  interstratified  with  thin  beds  of  limestone  and 

*  Clarke,  F.  W.     Constants  of  Nature,  Part  I,  pp.  81,  82. 


16  CEMENTS,  LIMES,  AND   PLASTERS. 

thicker  beds  of  red  shales.  Such  gypsum  beds  may  vary  greatly  in 
extent  as  well  as  in  thickness.  Beds  now  worked  in  different  American 
localities,  for  example,  vary  from  six  to  sixty  feet  in  thickness.  The 
gypsum  occurring  in  the  beds  frequently  contains  a  considerable  percent- 
age of  impurities,  as  is  shown  by  the  analyses  given  in  Table  8,  page  53. 

Deposits  of  rock  gypsum  have  been  formed  by  the  gradual  evapora- 
tion, in  lake  basins  or  shallow  arms  of.  the  sea,  of  waters  carrying  lime 
sulphate  in  solution.  If  any  natural  water  be  evaporated  to  a  suf- 
ficient extent,  it  will  deposit  the  salts  which  it  contains,  the  order  in 
which  the  various  salts  are  deposited  depending  principally  upon  their 
relative  proportions  in  the  water  and  their  solubility.  A  normal  water, 
whether  from  stream,  lake,  or  ocean,  will  carry  as  its  three  commonest 
constituents  lime  carbonate,  lime  sulphate,  and  sodium  chloride.  If 
such  a  water  be  evaporated,  therefore,  deposits  of  limestone,  gypsum, 
and  common  salt  would  result :  and,  as  above  noted,  these  three  minerals- 
are  very  common  associates  in  gypsum  deposits. 

Gypsum-earth  deposits  consist  of  masses  of  small  crystals  or  grains 
of  gypsum,  intermingled  usually  with  much  clayey  matter,  sand,  etc. 
Such  deposits  occur  in  depressions,  and  are  supposed  to  be  formed  by 
the  evaporation  of  sjpring-waters  which  have  taken  up  lime  sulphate 
in  solution  from  underlying  beds  of  rock  gypsum,  only  to  deposit  it 
again  on  reaching  the  surface  and  being  subjected  to  evaporation. 

In  certain  areas  in  the  West,  notably  in  Arizona  and  New  Mexico, 
deposits  of  gypsum  sand  occur.  These  deposits  are  made  up  of  fine 
grains  of  gypsum,  worn  off  from  outcrops  of  rock  gypsum  and  carried 
by  the  wind  to  the  place  of  deposition. 

Geologic  distribution  of  gypsum  deposits. — Gypsum  has  a  very  wide 
geological  range,  but  the  workable  gypsum  deposits  of  the  United  States 
occur  at  only  a  few  geological  horizons.  The  Salina  group  of  the  Silurian 
carries  large  gypsum  deposits  which  are  worked  in  New  York,  Ontario, 
Ohio,  and  Michigan.  The  Lower  Carboniferous  carries  workable  gypsum 
deposits  in  Virginia,  Michigan,  and  Montana.  Most  of  the  deposits 
west  of  the  Mississippi  occur  in  rocks  of  Permian  or  somewhat  later  age. 
Three  geological  series,  therefore,  carry  almost  all  of  the  workable 
gypsum  of  the  United  States. 

Distribution  of  gypsum  in  the  United  States. — The  gypsum-producing 
localities  of  the  United  States  are  indicated  on  the  accompanying  map. 
This  map  is  taken  from  the  publication  cited  below,*  to  which  the  reader 

*  "Gypsum  Deposits  of  the  United  States,"  by  George  I.  Adams  and  others. 
Bulletin  No.  223,  U.  S.  Geological  Survey.     Washington,  D.  C. 


COMPOSITION,  DISTRIBUTION,  AND  EXCAVATION  OF  GYPSUM       17 

is  referred  for  a  much  more  detailed  discussion  of  the  subject,  and  from 
which  most  of  the  descriptive  matter  given  below  has  been  abstracted. 

East  of  the  Mississippi  River,  the  producing  localities  are  confined 
to  central  and  western  New  York,  southwestern  Virginia,  northern 
Ohio,  and  two  widely  separated  areas  in  Michigan;  while  a  large  unworked 
deposit  occurs  in  Florida.  West  of  that  river,  gypsum  deposits  are 
both  numerous  and  widely  distributed,  and  plaster-mills  are  in  operation 
in  fourteen  of  the  Western  States  and  Territories. 

Brief  descriptions  of  the  gypsum  resources  of  the  various  States 
are  given  below,  the  States  being  taken  up,  for  convenience  of  reference, 
in  alphabetical  order. 

Arizona. — Gypsum  can  be  obtained  in  quantity  at  several  localities 
in  southern  Arizona,  the  following  being  particularly  noteworthy: 
(1)  In  the  Santa  Rita  Mts.,  Pima  County,  southeast  of  Tucson;  (2)  in 
the  low  hills  along  the  course  of  San  Pedro  River,  Cochise  and  Final 
counties;  (3)  in  the  Sierrita  Mts.,  Pima  County,  south  of  Tucson;  (4)  in 
the  foothills  of  the  Santa  Catalina  Mts.,  Pima  County,  north  of  Tucson; 
(5)  on  the  Fort  Apache  Reservation,  Navajo  County.  Of  these  localities 
only  the  fourth,  north  of  Tucson,  has  as  yet  been  commercially  developed. 

California. — In  the  Tertiary  rocks  of  California  gypsum  is  widely 
distributed.  It  is  found  throughout  nearly  all  the  Coast  Ranges,  par- 
ticularly south  of  San  Francisco  Bay,  in  the  foothills  of  the  Great  Valley, 
and  in  the  valleys  of  southern  California.  Deposits  are  known  to  occur 
in  the  counties  of  Fresno,  Kings,  Monterey,  Kern,  San  Luis  Obispo, 
Santa  Barbara,  Ventura,  Los  Angeles,  San  Bernardino,  Riverside,  and 
Orange. 

Colorado. — The  gypsum-producing  localities  of  Colorado  occur  at 
intervals  from  the  northern  to  the  southern  border  of  the  State,  along 
the  eastern  foothills  of  the  Rocky  Mountains.  "Gypsum  has  been 
worked  extensively  near  Loveland:  beds  hava  also  been  opened  on 
Bear  Creek,  near  Morrison,  and  eight  miles  to  the  southeast,  on  Deer 
Creek.  Quarries  have  been  developed  near  Perry  Park  and  in  the 
Garden  of  the  Gods,  near  Colorado  City,  and  also  in  the  vicinity  of  Canyon 
City."  Other  deposits,  as  yet  unworked,  are  known  to  occur  in  the 
central  and  western  parts  of  the  State. 

Florida. — An  extensive  area  of  gypsum,  6  to  8  feet  thick,  has  been 
described  as  occurring  about  six  miles  west  of  Panasoffkee,  Fla.,  on 
a  low-lying  area  of  hummock-land  known  as  Bear  Island.  The  material 
has  not,  as  yet,  been  exploited. 

Iowa. — The  gypsum  of  Iowa  is  confined  to  a  single  area  of  60  to  70 
square  miles,  near  Fort  Dodge,  Webster  County.  The  material  occurs 


18  CEMENTS,  LIMES,  AND  PIASTERS. 

in  one  bed,  which  varies  from  10  to  25  feet  in  thickness.  It  has  been 
extensively  worked,  eight  plaster-mills  being  now  in  operation  in  the 
district. 

Kansas. — "The  gypsum  of  Kansas  consists  of  extensive  beds  of 
rock  gypsum  and  a  number  of  deposits  of  secondary  gypsum,  or  gypsite. 
Some  of  the  rock  gypsum  is  suited  to  the  manufacture  of  the  finer  grades 
of  plaster  of  Paris,  and  the  gypsite  is  particularly  adapted  for  wall  and 
cement  plasters.,  There  is  a  sufficient  quantity  of  the  gypsite  now 
known  to  permit  extensive  operations  for  a  number  of  years.  Certain 
of  the  deposits,  however,  have  shown  signs  of  exhaustion,  and  have 
been  abandoned.  It  is  probable  that  others  will  be  discovered,  as  there 
is  a  demand  for  further  development  of  the  industry.  The  rock-gypsum 
beds  are  so  vast  in  their  proportions  that  only  those  which  are  favorably 
situated  with  respect  to  transportation  facilities  will  probably  be  worked. 

"The  area  in  which  gypsum  is  found  is  an  irregular  belt  extending 
northeast  and  southwest  across  the  State,  as  indicated  on  the  accom- 
panying map  of  Kansas  (Fig.  2).  It  is  naturally  divided  into  three 
districts,  which,  from  the  important  centers  of  manufacture,  may  be 
named  the  northern  or  Blue  Rapids  area,  in  Marshall  County;  the  central 
or  Gypsum  City  areaj  in  Dickinson  and  Saline  counties;  and  the  southern 
or  Medicine  Lodge  area,  in  Barber  and  Comanche  counties.  A  number 
of  small  areas  have  been  developed  between  these,  connecting  more 
or  less  closely  the  three  main  areas.  The  gypsum  is  found  at  Manhattan 
and  north  of  that  city,  though  not  worked.  It  is  worked  at  Langford, 
in  the  southern  part  of  Clay  County,  and  is  found  near  Manchester, 
in  the  northern  part  of  Dickinson  County.  Gypsum  is  worked  near 
Burns,  and  has  in  past  years  been  worked  near  Peabody  and  Furley, 
and  large  deposits  are  known  near  Tampa.  Farther  south,  in  Sumner 
County,  a  large  mill  has  been  operated  at  Mulvane,  and  gypsum  has 
been  quarried  at  Geuda  Springs.  These  different  localities  show  an 
almost  continuous  belt  of  gypsum  across  the  State." 

Michigan. — Gypsum  is  at  present  worked  in  two  distinct  areas  in 
Michigan,  while  a  third  locality  may  prove  to  be  of  importance  in  the 
future.  The  two  producing  areas  are  (1)  in  the  vicinity  of  Grand  Rapids  ; 
and  (2)  at  Alabaster,  near  Saginaw  Bay.  The  third,  and  as  yet  unex- 
ploited,  area  is  near  St.  Ignace,  on  the  Upper  Peninsula. 

•Montana. — Gypsum  is  worked  for  plaster  in  Cascade  and  Carbon 
counties,  and  is  known  to  occur  at  many  other  localities  in  the  State. 

Nevada. — At  Moundhouse  and  Lovelocks,  in  northwestern  Nevada, 
gypsum  deposits  have  been  developed.  Large  deposits  also  occur  in 
southern  Nevada. 


COMPOSITION,  DISTRIBUTION,  AND  EXCAVATION  OF  GYPSUM.     19 


20 


CEMENTS,  LIMES,  AND  PLASTERS. 


COMPOSITION,  DISTRIBUTION,  AND  EXCAVATION  OF  GYPSUM.     21 

New  Mexico. — Though  gypsum  is  known  to  occur  in  quantity  at 
many  points,  the  only  commercial  development  has  been  at  Ancho, 
where  a  plaster-mill  is  now  in  operation. 

New  York. — The  gypsum  in  New  York  State  occurs  as  rock  gypsum 
interbedded  with  shales  and  shaly  limestones.  Several  gypsum  beds, 
separated  by  shales,  usually  occur  in  any  given  section.  They  are 
lenticular  in  shape,  but  of  such  horizontal  extent  that  in  any  given 
quarry  they  are  usually  of  practically  uniform  thickness.  Those  that 
are  worked  vary  from  4  to  10  feet  in  thickness  in  most  of  the  quarries, 
but  at  Fayetteville  a  30-foot  bed  is  exposed.  The  area  in  which  the 
gypsum-bearing  formations  are  found  as  shown  in  the  map,  Fig.  3, 
extends  through  the  central  part  of  the  State,  the  productive  portion, 
of  the  belt  including  parts  of  Madison,  Onondaga,  Cayuga,  Ontario, 
Genesee,  Monroe,  Livingston,  and  Erie  counties. 

The  most  easterly  points  at  which  gypsum  has  been  worked  are  in 
Madison  County,  but  the  product  there  is  small  and  is  marketed  locally 
for  use  as  land-plaster.  In  Onondaga  County,  at  Marcellus,  Fayetteville, 
and  other  points,  large  quarries  are  operated,  part  of  the  product  being 
calcined  and  part  ground  for  land-plaster.  The  quarries  near  Union 
Springs,  in  Cayuga  County,  produce  principally  land-plaster,  as  do 
those  of  Phillipsport,  Gibson,  and  Victor,  in  Ontario  County.  The 
gypsum  from  Mumford,  Wheatland,  Garbuttville,  and  Oakfield  is  used 
chiefly  for  calcined  plaster. 

Ohio. — "The  gypsum  deposits  of  Ohio  which  are  of  economic 
value  consist  of  beds  of  rock  gypsum  occurring  in  the  northwestern 
part  of  the  State.  They  have  been  known  since  the  first  settlements 
were  made  on  the  northern  shore  of  Sandusky  Bay.  The  expo- 
sures lie  at  about  the  level  of  the  waters  of  the  bay,  in  some  places 
rising  a  few  feet  above  it.  In  addition  to  the  deposits  of  economic 
importance,  gypsum  is  found  in  small  pockets  and  isolated  bodies 
throughout  the  area  of  the  Salina  group,  which  occurs  extensively  in 
northwestern  Ohio.  The  deposits  which  are  worked  vary  considerably 
in  thickness,  ranging  from  a  few  inches  up  to  9  feet.  On  the  north 
shore  of  Sandusky  Bay,  in  Portage  Township,  Ottawa  County,  1500 
to  2000  acres  of  land  have  been  thoroughly  prospected  with  a  core- 
drill,  and  it  has  been  shown  that  there  are  from  150  to  200  acres  of 
workable  gypsum.  On  the  south  shore  of  the  bay,  about  2J  miles 
northwest  of  the  town  of  Castalia,  drilling  has  shown  the  presence 
of  another  area  of  workable  gypsum,  but  no  developments  have 
yet  been  undertaken.  The  location  of  these  deposits  is  shown  on 
the  accompanying  map,  Fig.  4.  It  is  estimated  that  at  the  present 


22 


CEMENTS,  LIMES,  AND  PLASTERS. 


COMPOSITION,  DISTRIBUTION,  AND  EXCAVATION  OF  GYPSUM.     23 

rate   of   production   the    known  deposits  will  last   about   twenty-five 
years." 

Oklahoma. — Oklahoma  occupies  a  central  position  in  the  belt  of 
country  which  carries  extensive  gypsum  deposits  all  the  way  from  the 
northern  part  of  Kansas  into  central  Texas  (see  Fig.  I).  Within  its 
borders  the  number  and  thickness  of  the  beds  appear  to  be  greater  than 
to  the  north  and  south.  "  TJie  amount  of  gypsum  appears  to  be  inex- 
haustible. With  perhaps  two  exceptions,  each  of  the  western  counties 
contains  enough  material  to  supply  the  United  States  for  an  indefinite 
length  of  time,  and  there  are  in  addition  considerable  deposits  in  the 
eastern  part  of  the  Territory."  The  gypsum  in  Oklahoma  may  be  con- 
sidered as  occurring  in  four  regions:  (1)  the  Kay  County  region;  (2)  the 
main  line  of  gypsum  hills,  extending  from  Canadian  County  northwest 
through  Kingfisher,  Blaine,  Woods,  and  Woodward  counties  to  the 
Kansas  line;  (3)  the  second  gypsum  hills,  parallel  with  the  main  gypsum 
hills,  and  from  50  to  70  miles  farther  southwest,  which  extend  from  the 
Keechi  Hills,  in  southeastern  Caddo  County,  northwestward  through 
Washita,  Custer,  Dewey,  and  Day  counties;  and  (4)  the  Greer  County 
region,  occupying  the  greater  part  of  western  Greer  County  and  the 
extreme  southeastern  corner  of  Roger  Mills  County. 

The  deposits  in  Kay  County  consist  of  earthy  gypsum,  or  gypsite. 
In  the  other  three  regions  rock  gypsum  predominates,  although  there 
are  numerous  localities  where  earthy  gypsum  occurs  in  workable  bodies. 

Oregon. — Gypsum  occurs  in  Oregon  in  only  one  known  and  exploited 
locality.  This  is  on  the  eastern  border  of  the  State,  near  the  middle 
point  of  the  boundary-line,  on  a  ridge  dividing  Burnt  River  and  Snake 
River.  A  plaster-plant  Ipcated  at  Lime  uses  material  from  this  locality. 

South  Dakota.— "In  the  Black  Hills  uplift  there  is  brought  to  the 
surface  an  elliptical  outcrop  of  the  Red  Beds  surrounding  the  high  ridges 
and  plateaus  of  the  central  portion  of  the  Black  Hills.  The  area  is 
about  100  miles  long  by  50  miles  wide,  and  the  outcrop  zone  has  an 
average  width  of  3  miles,  except  in  a  few  districts  where  the  rocks  dip 
steeply,  where  it  is  much  narrower.  The  formation  consists  mainly 
of  red  sandy  shales,  with  included  beds  of  gypsum  at  various  horizons, 
some  of  which  are  continuous  for  long  distances,  while  others  are  of 
local  occurrence.  The  thickness  of  the  deposits  varies  greatly,  but  in 
some  districts  over  30  feet  of  pure  white  gypsum  occur,  and  nearly 
throughout  the  outcrop  of  the  formation  it  contains  deposits  of  suffi- 
cient thickness  and  extent  as  to  have  commercial  value. 

"The  gypsum  is  a  prominent  feature  about  Hot  Springs.  Here  the 
principal  beds  occur  about  60  feet  above  the  base  of  the  formation  and 


"24  CEMENTS,  LIMES,  AND  PLASTERS. 

have  a  thickness  of  33J  feet,  exclusive  of  the  10-foot  parting  of  shale 
between  them,  but  this  thickness  diminishes  somewhat  northward  and 
rapidly  southward/' 

Texas. — "The  largest  area  in  Texas  containing  deposits  of  gypsum 
lies  east  of  the  foot  of  the  Staked  Plains,  in  northern  Texas.  The  beds 
have  an  approximately  northeast-southwest  strike  and  extend  from  Red 
River  to  the  Colorado  in  an  irregular  line,  the  sinuosities  of  which  are 
produced  by  the  valleys  of  the  eastward-flowing  streams.  This  belt 
is  a  continuation  of  the  deposits  in  Oklahoma. 

"In  the  eastern  part  of  El  Paso  County,  to  the  east  of  Guadaloupe 
rriountains,  there  is  an  area  of  gypsum  which  extends  beyond  the  bor- 
der of  the  State  northward  into  New  Mexico.  It  lies  north  of  the 
Texas-Pacific  Railroad  and  west  of  Pecos  River.  In  a  few  localities 
this  great  plain  of  gypsum  is  overlain  by  beds  of  later  limestone  and 
conglomerate.  The  gypsum  is  conspicuously  exposed  along  the  course 
of  Delaware  Creek,  a  stream  rising  in  the  foothills  of  the  Guadaloupe 
Mountains  and  flowing  eastward  into  the  Pecos. 

"In  the  Malone  Mountains  in  El  Paso  County  there  is  a  third  area 
which  contains  notable  deposits  of  rock  gypsum.  This  locality  has 
the  advantage  of  being  situated  near  the  Southern  Pacific  Railway." 

Utah. — "The  more  important  known  deposits  occur  in  the  central 
;and  southern  portions  of  the  State,  in  Juab  County,  east  of  Nephi;  in 
Sanpete  and  Sevier  counties,  near  Salina;  in  Millard  County,  at  White 
Mountain,  near  Fillmore,  and  in  Wayne  County  in  South  Wash.  They 
.are  all  of  the  rock-gypsum  type,  except  the  one  near  Fillmore,  which  is 
in  the  secondary  form  of  unconsolidated  crystalline  and  granular  gypsum 
blown  up  from  dry  lakes  into  dunes.  Deposits  are  also  known 
in  Emery  County,  about  forty  miles  southeast  of  Richfield;  in  Kane 
County,  near  Kanab;  in  Grand  County,  between  Grand  River  and 
the  La  Sal  Mountains;  in  Sanpete  County,  near  Gunnison;  in  the  eastern 
part  of  Washington  County  (?),  between  Duck  Lake  and  Rockville, 
and  at  other  places.  Recently  enormous  deposits  of  gypsum  have 
been  reported  from  Iron  County,  at  points  so  far  from  lines  of  trans- 
portation, however,  as  to  render  their  exploitation  impracticable  for 
the  present." 

Virginia. — All  the  workable  gypsum  deposits  of  Virginia  occur  in 
Washington  and  Smyth  counties,  in  the  valley  of  the  North  Fork  of 
Holston  River.  The  area  within  which  the  known  deposits  are  located 
is  a  narrow  belt  about  sixteen  miles  in  length,  extending  from  a  short 
distance  southwest  of  Saltville'  to  a  point  about  three  miles  west  of 
Chatham  Hill  post-office. 


COMPOSITION,  DISTRIBUTION,  AND  EXCAVATION  OF  GYPSUM.     25 

The  material  occurs  as  rock  gypsum,  interbedded  with  shales  and 
shaly  limestones  of  Carboniferous  age.  The  beds  of  gypsum  average 
30  feet  in  thickness  at  the  localities  at  which  they  are  now  worked. 
The  rocks  of  the  district  dip  at  a  high  angle,  however,  usually  between 
25°  and  45°,  so  that  certain  wells  which  have  been  drilled  are  in  the 
gypsum  for  long  distances,  and  accordingly  immense  thicknesses  of 
gypsum  have  been  erroneously  reported,  because  the  inclination  of 
the  deposits  was  not  taken  into  account.  Near  Saltville  the  dip  of  the 
gypsum  beds  which  are  worked  is  toward  the  northwest;  at  the  mines 
farther  up  the  valley  the  dip  is  to  the  southeast. 

The  development  of  the  gypsum  industry  in  this  area  has  been 
governed  almost  entirely  by  the  transportation  facilities.  The  deposits 
in  the  upper  valley,  though  extensive  and  easily  workable,  have  not 
been  largely  exploited,  owing  to  the  long  wagon-haul  necessary.  The 
deposits  at  Saltville  and  Plasterco,  which  are  on  a  branch  of  the  Nor- 
folk and  Western  Railroad,  have  furnished  the  principal  output. 

Throughout  the  entire  area  the  dip  of  the  gypsum  beds  is  so  high 
as  to  require  mining,  except  at  the  commencement  of  the  working. 

Wyoming. — Though  gypsum  deposits  occur  at  many  localities  in  the 
State,  only  two  plaster-plants  are  at  present  in  operation.  These  are 
located  at  Laramie  and  Red  Buttes  respectively.  A  considerable  exten- 
sion of  the  Wyoming  plaster  industry  may,  however,  be  expected;  for 
the  supplies  of  gypsum  are  large  and  accessible. 

Canada. — Gypsum  occurs  in  New  Brunswick,  associated  with  Lower 
Carboniferious  limestones,  particularly  large  deposits  being  shown 
near  Hillsboro,  Albert  County.  An  analysis  of  a  typical  sample  from 
Hillsboro  is  given  as  no.  25,  of  Table  8,  page  53. 

The  gypsum  deposits  of  Ontario  occur  in  the  form  of  beds,  associated 
with  shales  and  limestones,  in  the  Salina  group.  The  principal  exploited 
deposits  are  located  along  the  valley  of  Grand  River,  from  Paris  in 
Brant  County  to  near  Cayuga  in  Haldimand  County. 

Extensive  gypsum  beds  also  occur  in  Devonian  limestones  along  the 
Moose  and  French  rivers,  near  James  Bay:  but  these  deposits  are  as 
yet  entirely  undeveloped. 

In  Nova  Scotia  thick  beds  of  gypsum  occur  near  St.  John  Harbor, 
Port  Bevis,  and  Baddeck  Bay,  associated  with  Carboniferous  limestones. 
An  analysis  of  gypsum  from  near  Baddeck  Bay  is  given  as  no.  26  of 
Table  8,  page  53. 

Of  the  Canadian  gypsum  deposits,  those  of  New  Brunswick  and 
Nova  Scotia  are  of  interest  to  American  producers,  for  they  have  sup- 
plied large  quantities  of  crude  gypsum  to  plaster  plants  located  in  the 


26 


CEMENTS,  LIMES,  AND  PLASTERS. 


United  States.  Most  of  this  Canadian  gypsum  is  used  in  plants  located 
in  the  seaboard  cities,  but  a  considerable  amount  of  it  is  calcined  as  far 
inland  as  Syracuse,  N.  Y. 

References  on  gypsum  deposits. — The  following  list,  arranged  by 
States,  will  serve  to  locate  the  principal  papers  on  various  gypsum 
deposits. 


ARIZONA. 
CALIFORNIA. 


COLORADO. 


FLORIDA. 


IOWA. 


KANSAS, 


Blake,  W.  P.     Gypsum  deposits  in  Arizona.     Bulletin  223, 

U.  S.  Geol.  Survey,  pp.  100,  1Q1.     1904. 
Fairbanks,  H.  W.     Gypsum  deposits  in  California.     Bulle- 
tin 223,  U.  S.  Geol.  Survey,  pp.*119-123.     1904. 
Grimsley    G.  P.      Gypsum    and    cement    plaster    industry 

in     California.       Eng.    and    Mining    Journal,    June    8, 

1901. 
Anon.     Gypsum  (localities  in  California).     12th  Ann.   Rep0 

California  State  Mineralogist,   pp.   323-325.     1894. 
Lakes,    A.     Gypsum    and    clay    in    Colorado.     Mines    and 

Minerals,  vol.  20,  Dec.,  1899. 
Lakes,  A.     Gypsum    deposits    in    Colorado.     Bulletin    223, 

U.  S.  Geol.  Survey,  pp.  86-88.     1904. 
Lee,    H.    A.     Larimer    County    gypsum.     Stone,    vol.    21, 

pp.  35-37.     1900. 
Day,  D.  T.     Gypsum  in  Florida.     20th  Ann.  Rep.  U.  S. 

Geol.  Survey,  pt.  6,  pp.  662,  663.     1899. 
Day,   D.   T.     Gypsum  deposits  in  Florida.     Bulletin  223, 

U.  S.  Geol.  Survey,  p.  48.     1904. 
Keyes,  C.  R      Gypsum  deposits  of  Iowa.     Vol.  3,  Reports 

Iowa  Geological  Survey,  pp.  257-304.     1895. 
Keyes,   C.    R.     Iowa   gypsum.     Mineral   Industry,   vol.   4; 

pp.  379-396.     1896. 
Wilder,    F.    A.     Geology    of    Webster    County.     Vol.    12, 

Reports  Iowa  Geol.  Survey,  pp.  63-235.     1902. 
Wilder,   F.   A.     Gypsum  deposits  in  Iowa.     Bulletin  223, 

U.  S.  Geol.  Survey,  pp.  49-52.     1904. 
Bailey,  E.  H.  S.,  and  Whitten,  W.  M.     On  the  chemical 

composition   of  some   Kansas   gypsum  rocks.      Kansas 

University  Quarterly,  vol.  6,  pp.  29-34.     1897. 
Crane,  W.  R.     Mining  and  milling  of  gypsum  in  Kansas. 

Eng.  and  Mining  Journal,  Nov.  9,  1901. 
Grimsley,  G.  P.,  and   Bailey,  E.  H.  S.      Special  report  on 

gypsum  and  gypsum  cement  plasters.     Vol.  5,  Reports 

Kansas  Geological  Survey.     1899. 
Grimsley,  G.  P.    Gypsum  deposits  in  Kansas.     Bulletin  223, 

U.  S   Geol.  Survey,  pp.  53-59.     1904. 


COMPOSITION,  DISTRIBUTION,  AND  EXCAVATION  OF  GYPSUM.     27 

MICHIGAN.  Gregory,  W.  M.     Gypsum  in  Arenac  and  adjoining  counties. 

Ann.  Rep.  Michigan  Geol.  Surveyfor  1901,  pp.    15-18. 
1902. 

Grimsley,  G.  P.     Preliminary  report  on  the  gypsum  deposits 
of  Michigan.     Ann.  Rep.  Michigan  Geol.  Survey  for  1902, 
pp.  4-10.     1903. 
Grimsley,  G.  P.     Gypsum  deposits  in  Michigan.     Bulletin 

223,  U.  S.  Geol.  Survey,  pp.  45-47.     1904. 
Grimsley,  G.  P.     A  theory  of  origin  for  the  Michigan  gypsum 
deposits.     American    Geologist,   vol.   34,    pp.    378-387. 
Dec.,  1904. 

Grimsley,  G.  P.     The  gypsum  of  Michigan  and  the  plaster 
industry.     Vol.  9,   pt.  2,    Reports   Michigan   Geol.    Sur- 
vey.   1904. 
MONTANA.  Weed,  W.  H.     Gypsum  deposits  in  Montana.     Bulletin  223, 

U.  S.  Geol.  Survey,  pp.  74,  75.     1904. 
NEVADA.  Louderback,  G.  D.     Gypsum  deposits  in  Nevada.     Bulletin 

223,  U.  S.  Geol.  Survey,  pp.  112-118.     1904. 
NEW  MEXICO.        Herrick,  H.  N.     Gypsum  deposits  in  New  Mexico.     Bulletin 

223,  U.  S.  Geol.  Survey,  pp.  89-99.     1904. 
N-EW  YORK.  Clarke,  W.  C.     The  gypsum  industry  in  New  York  State. 

Bulletin  11,  N.  Y.  State  Museum,  pp.  70-84.     1893. 
Eckel,  E.  C.     Gypsum  deposits  in  New  York.     Bulletin  223, 

U.  S.  Geol.  Survey,  pp.  33-35.     1904. 

Lincoln,   D.   F.     Report   on   the   structural   and  economic 
geology    of    Seneca    County,    N.    Y.     14th    Ann.    Rep. 
N.  Y.  State  Geologist,  pp.  60-125.     1896. 
Luther,  D.  D      The  economic  geology  of  Onondaga  County, 
New  York.     15th  Ann.    Rep.  N.  Y.  State  Geologist,  vol. 
1,  pp.  241-303.     1897. 
Merrill,  F.  J.  H.     Salt  and  gypsum  industries  of  New  York. 

Bulletin  11,  N.  Y.  State  Museum,  89  pp.     1893. 
Parsons,  A.   L.     Recent   developments  in  the  gypsum  in- 
dustry in  New  York  State.     20th  Ann.  Rep.  N.  Y.  State 
Geologist,  pp.  177-183.     1902. 

Pohlman,  J.  Cement  rock  and  gypsum  deposits  in  Buffalo. 
Trans.  Am.  Inst.  Min.  Engrs.,  vol.  17,  pp.  250-253. 
1889. 

OHIO.  Orton,  E.     Gypsum  or  land  plaster  in  Ohio.     Vol.  6,  Re- 

ports Geol.  Survey  Ohio,  pp.  696-702.     1888. 
Peppel,   S.   V.     Gypsum   deposits  in   Ohio.     Bulletin  223, 

U.  S.  Geol.  Survey,  pp.  38-44.     1904. 

OKLAHOMA.  Gould,    C.     N.     Oklahoma    gypsum.     2d    Biennial    Rep. 

Oklahoma  Dept.  Geology,  pp.  75-137.     1902. 


28 


CEMENTS,  LIMES,  AND   PLASTERS. 


OKLAHOMA.  Gould,  C.  N.     Gypsum  deposits  in  Oklahoma.     Bulletin  223, 

U.  S.  Geol.  Survey,  pp.  60-67      1904. 
OREGON.  Lindgren,  W.     Gypsum  deposits  in  Oregon.     Bulletin  223, 

U.  S.  Geol.  Survey,  p.  111.     1904. 

SOUTH  DAKOTA.     Darton,  N.  H.     Gypsum  deposits  in  South  Dakota.      Bulle- 
tin 223,  U.  S.  Geol.  Survey,  pp.  76-78.     1904. 
TEXAS.  Hill,  B.  F.     Gypsum  deposits  in  Texas.     Bulletin  223,  U.  S. 

Geol.  Survey,  pp.  08-73.     1904. 
UTAH.  Bout  well,  J.  M.     Gypsum  deposits  in  Utah.     Bulletin  223, 

U.  S.  Geol.  Survey,  pp.  102-110.     1904. 
VIRGINIA.  Boyd,  C.  R.     Gypsum  in  southwestern.  Virginia.     Resources 

of  southwest  Virginia,  8vo,  pp.  104-108.     1881. 
Eckel,  E.  C.     Salt  and  gypsum  deposits  of  southwestern 
Virginia.     Bulletin  213,  U.  S.  Geol.  Survey,  pp.  406-416. 
1903 
Eckel,  E.  C.     Gypsum  deposits  in  Virginia.     Bulletin  223, 

U.  S.  Geol.  Survey,  pp.  36-37.     1904. 

Stevenson,    J.    J.     Notes    on    the    geological    structure    of 

Tazewell,     Russell,     Wise,     Smythe,     and    Washington 

counties  of  Virginia.       Proc.  Amer.  Philos.  Soc.,  vol.  22, 

pp.  114-161.     1885. 

WYOMING.  Knight,  W.  C.     Gypsum  deposits  in  Wyoming.     Bulletin 

223,  U.  S.  Geol.  Survey,  pp.  79-85.     1904. 
Slosson,  E.  E.,  and  Moudy,  R.  B.     The  Laramie  cement 
plaster.     10th  Ann.  Rep.  Wyoming  Agricultural  College. 
1900. 

CANADA.  Bailey,  L.  W.,  and  Ells,  R.  W.     Report  on  the  Lower  Car- 

bonaceous belt  of  Albert  and  Westmorland  counties, 
New  Brunswick.  Report  Canadian  Geological  Survey 
for  1876-77,  pp.  351-401  1878. 

Bell,  R.,  and  others.  [Gypsum  and  plaster  in  Ontario.] 
Report  on  the  mineral  resource.!  of  Ontario,  pp.  119-123. 
1890. 

Fletcher,  H.      Report   of  explorations  and  surveys  in  Cape 
Breton,     Nova    Scotia.     Report     Canadian    Geological 
Survey  for  1875-76,  pp.  369-418.     1877. 
Gesner,   A.     On  the   gypsum   of  Nova   Scotia.     Quarterly 
Journal  Geological  Society,  vol.  5,  pp.  129,  130.     1849. 
Gilpin,  E.     The  gypsum  of  Nova  Scotia.     Trans.  North  of 
England  Institute  of  Mining  Engineers,  vol.  30,  p.  68. 
1881. 
,    Nicol,    W.     Anhydrite    in    Ontario.     Canadian    Record    of 

Science,  vol.  7,  p.  61.     1896. 

Anon.  Nova  Scotia  gypsum.  Canadian  Mining  Review, 
March  1896. 


COMPOSITION,  DISTRIBUTION,  AND  EXCAVATION  OF  GYPSUM.     29* 

Excavation  and  handling  of  rock  gypsum. — Deposits  of  rock  gypsum 
are  worked  either  in  open  quarries  or  in  mines,  the  choice  depending 
on  the  thickness  of  the  bed,  its  dip,  and  the  amount  of  stripping  neces- 
sary. Usually  work  is  commenced  in  an  open  cut  on  the  outcrop  of 
the  gypsum  bed.  After  the  entire  available  face  on  the  property  has 
been  opened  in  this  manner,  it  is  necessary  to  decide  whether  the  work- 
ings can  be  most  economically  driven  as  underground  tunnels  or  slopes, 
or  by  stripping  and  open-cut  work.  At  the  Severance  quarries  at 
Fayetteville,  N.  Y.,  over  40  feet  of  shale  and  limestone  stripping  is 
removed,  but  the  total  thickness  of  gypsum  beds  shown  here  is  60  feet; 
and  such  heavy  stripping  could  not  be  justified  in  order  to  work  thinner 
beds. 

Under  ordinary  conditions  the  cost  of  quarrying  gypsum  may  range 
from  20  to  35  cents  per  ton,  as  compared  with  40  to  60  cents  per  ton 
for  mining  it.  In  mining,  large  pillars  must  be  left  at  frequent  intervals,, 
and  timbering  is  necessary,  in  addition,  for  extensive  workings. 

Mining  methods. — The  mining  methods  practiced  at  a  typical  Kansas 
locality  are  described  *  as  follows  by  Crane : 

"As  a  rule,  there  is  little  or  no  system  employed  in  laying  out  the- 
workings.  Main  lines  of  haulage  are  run  as  continuations  of  the  sur- 
face drifts,  other  openings  being  run  parallel  with  them  on  further  de- 
velopment, or  run  from  the  foot  of  a  shaft  sunk  to  the  workable  deposit. 
On  one  or  both  sides  of  the  haulageways  rooms  are  driven,  which 
often  run  together,  thus  leaving  odd  and  very  irregularly  shaped  pillars. 
Long  working-faces  are  often  formed,  which  must  be  again  broken 
by  passages  forming  pillars  for  the  support  of  the  roof.  Usually,  how- 
ever, single  rooms,  more  or  less  irregular  in  shape,  are  opened  up  and 
worked  until  the  handling  of  the  product  becomes  inconvenient,  when 
new  and  more  advantageously  placed  openings  are  begun. 

"  The  mine  in  question  was  opened  by  an  adit,  which,  beginning  on 
a  fairly  steep  hillside,  at  a  point  on  a  level  with  the  second  floor  of 
the  mill,  extends  into  the  hill  for  a  distance  of  about  1000  feet.  No 
special  attempt  was  made  to  align  the  adit,  consequently  considerable 
useless  work  was  done.  For  the  first  400  feet  the  adit  runs  approxi- 
mately north;  the  next  300  feet  shows  a  marked  variation  from  the 
north-and-south  line.  An  attempt  was  then  made  to  rectify  the  devia- 
tion by  driving  a  right-angled  offset  25  feet  in  length;  the  remaining 
300  feet  was  driven  approximately  parallel  with  the  first  400  feet. 

*  Crane,  W.  R.  The  gypsum-plaster  industry  of  Kansas.  Eng.  and  Mining; 
Journal,  p.  442,  March  17,  1904. 


30  CEMENTS,  LIMES,  AND  PLASTERS. 

•''  Unfortunately,  the  adit  was  driven  so  nearly  level  as  to  render 
drainage  very  difficult,  and  much  water  stands  in  depressions  on  the 
limestone  floor. 

"  The  adit  is  lined  with  rough-hewn  oak,  walnut,  and  red-elm  timber, 
except  the  last  300  feet,  which  has  round  timbers  of  similar  material. 
Three-quarter  sets — that  is,  sets  with  posts  and  caps  only — are  em- 
ployed. The  posts  and  caps  are  6  feet  2  inches  and  6  feet  4  inches 
long,  respectively,  both  being  8X8  iriches  in  section.  They  are  spaced 
36  inches.  The  posts  stand  on  a  limestone  stratum  2  feet  in  thickness, 
and  therefore  require  no  sills.  The  sets  for  the  first  700  feet  are  lagged 
with  2  X  12-inch  oak  plank ;  the  remaining  300  feet'  has  plank  lagging 
on  the  caps  and  pole-lagging  on  the  posts.  A  single  track  of  36-inch 
gauge  is  laid  in  the  middle  of  the  tunnel  for  the  mine-cars,  which  are 
drawn  by  mule-power.  The  cars  have  a  capacity  of  from  800  to  1000 
Ibs.  gypsum. 

"  The  gypsum  mined  is  8.5  feet  thick  and  is  won  by  shooting  it  from 
the  face  or  sides  of  the  rooms,  holes  being  bored  by  hand-operated 
post-augers,  Hardscop  make.  The  holes  are  1.5  inches  in  diameter  and 
range  from  3  to  6  feet  deep.  Black  powder  of  C  grade  is  usually  em- 
ployed, the  charge  ranging  from  6  to  14  inches  per  hole.  Squibs  are 
employed  in  firing  the  charges.  The  cost  of  explosive  per  ton  of  gypsum 
extracted  is  about  four  cents. 

A  4  X  6-foot  air-shaft  connects  the  end  of  the  adit  with  the  surface, 
96  feet  above." 

Working  gypsum-earth  deposits. — Deposits  of  gypsite  or  gypsum 
earth,  being  purely  surface  deposits  of  a  soft,  granular  material,  can 
be  worked  best  by  methods  entirely  different  from  those  used  in  ex- 
cavating rock  gypsum.  The  gypsum  earth  is  not  only  soft,  but  frequently 
carries  a  large  percentage  of  moisture:  and  as  it  freezes  deeply  because 
of  this  moisture,  the  Kansas  deposits  can  be  worked  only  during  warm 
weather.  If  the  gypsum  earth  is  covered  by  soil  or  sand,  this  is  stripped. 
The  gypsum  earth  is  then  loosened  by  disk  harrows  or  plows,  and  taken 
up  by  wheeled  scrapers.  It  is  then  taken  to  drying-sheds,  in  order 
to  get  rid  inexpensively  of  as  much  of  the  water  as  possible.  The  cost 
of  working  a  gypsum-earth  deposit,  under  average  conditions,  may 
fall  between  10  and  25  cents  per  ton. 


CHAPTER  II. 
CHEMISTRY  OF  GYPSUM-BURNING.     MANUFACTURE  OF  PLASTERS 

BEFORE  taking  up  the  actual  methods  and  details  of  plaster-manu- 
facture, it  will  be  of  advantage  to  discuss  briefly  the  chemical  and  physi- 
cal principles  on  which  the  industry  is  based. 

Chemistry  of  gypsum-burning.—  Pure  crude  gypsum  is  a  hydrous 
sulphate  of  lime,  with  a  chemical  formula  CaS04  +  2H20.  This  corre- 
sponds to  the  composition: 

f  fLime(CaO)  .......     32.  6%  1 

CaSO  +2H  O=  ]  Lime  sulPhate  (CaSO4)  j  Sulphur        trioxide  I  =79.1% 

i      (SO3)  ...........     46  .  5 

[Water  (H2O).  ..........  .................  =20.9 

100.0 

If  pure  crude  gypsum  he  heated  to  a  temperature  of  more  than 
212°  F.  and  less  than  400°  F.,  a  certain  definite  portion  of  the  water 
of  combination  will  be  driven  off,  and  the  gypsum  thus  partially  de- 
hydrated will  be  plaster  of  Paris.  Plaster  of  Paris  has  the  formula 
+  iH20,  corresponding  to  the  composition: 


Three  fourths  of  the  original  water  of  combination  have  therefore 
been  driven  off  in  the  course  of  the  process.  Dehydration  to  this  extent 
can,  as  above  noted,  be  accomplished  at  any  temperature  between 
212°  F.  and  400°  F.  In  actual  practice,  however,  it  is  found  most 
economical  of  fuel  and  time  to  carry  on  the  process  at  the  highest  allow- 
able temperatures;  and  330°  to  395°  F.  may  be  regarded  as  the  usual 
limiting  temperatures  for  plaster-manufacture. 

About  400°  F.  is  a  critical  temperature,  for  if  gypsum  be  heated  at 
temperatures  much  above  this,  it  loses  all  of  its  water  of  combination, 
becoming  an  entirely  anhydrous  sulphate  of  lime,  and  useless  as  a 
normal  plaster.  Under  certain  conditions,  however,  gypsum  burned 
at  temperatures  above  400°  F.  gains  valuable  properties.  Such  highly 

31 


32  CEMENTS,  LIMES,  AND  PLASTERS. 

burned  gypsum  products  will  be  considered  in  Chapter  IV,  under  the 
head  of  Flooring  and  Hard-finish  Plasters. 

Recurring  to  plasters  burned  at  temperatures  lower  than  400°  F., 
it  may  be  said  that  if  the  gypsum  is  pure,  the  resulting  plaster  will 
harden  or  set  very  rapidly  when  mixed  with  water,  reabsorbing  sufficient 
water  to  regain  its  original  comppsition  of  CaSO4  +  2H20.  Such  quick- 
setting  pure  plasters  are  conveniently  grouped  as  plaster  of  Paris.  If, 
however,  the  crude  gypsum  carried  a  large  percentage  of  impurities, 
or  if  certain  materials  are  added  to  the  plaster  after  burning,  the  product 
will  set  much  more  slowly.  Such  slow-setting  plasters  are  of  value  in 
structural  work,  and  are  marketed  under  the  somewhat  misleading 
name  of  '" cement  plasters".  The  term  is  unfortunate,  because  such 
"cement  plasters"  are  in  no  way  related  to  the  much  better  known 
" hydraulic  cements"  discussed  later  in  this  volume. 

Using  the  properties  above  noted  as  a  basis  for  classification,  the 
group  of  plasters  may  be  subdivided  as  follows: 

CLASSIFICATION  OF  PLASTERS. 

A.  Produced  by  the  incomplete  dehydration  of  gypsum,  the  calcination  being 
carried  on  at  a  temperature  not  exceeding  400°  F. 

1.  Produced  by  the  calcination  of  a  pure  gypsum,  no  foreign  materials 

being  added  either  during  or  after  calcination .  .  PLASTER  OF  PARIS. 

2.  Produced  by  1he  calcination  of  a  gypsum  containing  certain  natural 

impurities,  or  by  the  addition  to  a  calcined  pure  gypsum  of  cer- 
tain materials  which  serve  to  retard  the  set  of  the  product. 

CEMENT  PLASTER. 

B-  Produced  by  the  complete  dehydration  of  gypsum,  the  calcination  being 
carried  on  at  temperatures  exceeding  400°  F. 

3.  Produced  by  the  calcination  of  a  pure  gypsum. . .  FLOORING-PLASTER. 

4.  Produced  by  the  calcination,  at  a  red  heat  or  over,  of  gyosum  to 

which   certain   substances    (usually  alum   or  borax)    have   be3n 
added HARD-FINISH  PLASTER. 

Commercial  classification  of  plasters. — In  the  trade  the  names  above 
suggested  are  used  quite  extensively,  biit  at  times  in  a  careless  and 
indefinite  fashion. 

Calcined  plaster  commonly  means  a  burned  plaster  to  which  no 
rctarder  has  been  added.  If  the  gypsum  from  which  it  was  made  was 
pure,  the  resulting  calcined  plaster  will  be  a  plaster  of  Paris,  as  defined 
above.  If  the  gypsum  used  was  impure,  however,  the  resulting  calcined 
plaster  would  be  a  cement  plaster,  as  defined  above. 

Stucco  is  almost  a  synonym  for  plaster  of  Paris,  as  it  contains  no 
retarder  and  is  made  from  fairly  pure  gypsum:  but  the  product  handled 


MANUFACTURE  OF  PLASTERS.  33 

commercially  as  plaster  of  Paris  is  usually  more  finely  ground  than 
stucco  and  is  as  white  as  possible. 

Wall-plasters  are  made  by  adding  not  only  retarder  but  also  hair 
(or  some  other  fiber)  to  calcined  plaster. 

Keene's  " cement",  Parian  "cement",  etc.,  are  plasters  used  as 
hard  finishes  in  buildings.  Their  properties  are  due  to  certain  pecu- 
liarities of  their  manufacture,  for  which  reference  should  be  made  to 
Chapter  IV. 

In  the  present  chapter  the  manufacture  of  plaster  of  Paris,  cement 
plaster,  and  wall-plaster  will  be  taken  up,  and  followed  by  a  chapter  on 
the  properties  of  the  resulting  products.  The  manufacture  and  properties 
of  the  flooring  and  hard-finish  plasters  will  be  discussed  together  in 
Chapter  IV. 

Manufacture  of  Plaster  of  Paris,  "  Cement  Plaster",  and  Wall-plaster. 

Though  plaster  of  Paris  and  "cement  plasters"  are  very  distinct 
so  far  as  properties  and  fields  of  use  are  concerned,  their  processes  of 
manufacture  are  so  similar  that  they  will  be  treated  together  in  this 
chapter.  It  will  be  recalled  that  in  manufacturing  plaster  of  Paris  a 
pure  gypsum  is  used,  so  that  the  product  sets  very  rapidly,  while  in 
making  cement  plasters  slowness  of  set  is  obtained  either  by  using  a 
naturally  impure  gypsum  or  by  adding  a  retarder  to  the  material  during 
or  after  its  manufacture.  Aside  from  this  difference,  and  a  slight 
difference  in  the  calcining  temperature,  which  is  usually  somewhat 
lower  for  plaster  of  Paris  than  for  cement  plaster,  the  methods  employed 
in  making  the  two  products  are  closely  similar. 

Two  operations  are  necessary  in  manufacturing  both  kinds  of  plaster: 
the  raw  material  must  be  properly  calcined  and  finely  ground.  The 
grinding  may  either  precede  or  follow  the  burning,  for  the  order  of 
the  two  operations  depends  largely  upon  what  calcining  process  is  used. 
If  the  burning  is  carried  on  in  kettles,  the  grinding  is  usually  done  first; 
but  if  the  burning  is  carried  on  in  ovens  or  rotating  cylinders,  the  raw 
material  is  necessarily  or  advisably  fed  in  lumps,  and  the  fine  grinding, 
therefore,  follows  the  burning.  In  the  present  chapter  the  subject 
will  be  discussed  under  the  following  headings: 

(1)  Grinding  gypsum  and  plaster. 

(2)  Calcining  by  the  oven  process. 

(3)  Calcining  by  the  kettle  process. 

(4)  Calcining  by  the  rotary  cylinder  process. 

(5)  Addition  of  retarders  and  acceleration. 

(6)  Costs  of  plaster-manufacture. 


34 


CEMENTS,  LIMES,  AND  PLASTERS. 


Grinding  gypsum  and  plaster. — In  American  plants  using  the  kettle- 
calcining  process  the  gypsum  is  finely  pulverized  before  calcination. 
This  pulverizing  is  usually  accomplished  in  three  stages,  though  when 
gypsum  earth  is  used  instead  of  rock  gypsum  the  coarse  crushers  are 
dispensed  with.  The  three  stages  are: 

(1)  The  lump  gypsum,  as  quarried,  is  crushed  to  2-  to  4-inch  size 
in  a  Blake,  Gates,  or  other  coarse  crusher. 


FIG.  5. — Nipper  for  coarse  crushing  of  gypsum.     (Butterworth  &  Lowe.) 

(2)  The  product  of  the  coarse  crushers  is  fed  to  reducers  of  the 
coffee-mill  type,  which  crush  it  to  about  }  inch  or  so. 

(3)  The  final  pulverizing  is  accomplished  in  either  buhrstone  mills, 
Sturtevant  rock-emery  mills,  or  Stedman  disintegrators.     These  reduce 
the  gypsum  so  that  from  55  to  65  per  cent  will  pass  a  100-mesh  sieve, 
and  it  is  then  ready  to  be  fed  to  the  kettles. 

A  typical  series  of  gypsum-grinding  machinery  is  shown  in  Figs. 
5-8.  Fig.  5  shows  a  " nipper",  used  for  the  first  coarse  reduction. 
It  is  a  heavy  crusher  of  the  jaw  type,  and  when  used  for  gypsum- 
crushing  is  usually  equipped  with  corrugated  jaws,  in  order  to  pre- 
vent clogging.  The  machine  shown  in  the  illustration  has  a  jaw- 
opening  of  16i"X25f",  and  a  shipping-weight  of  10,200  Ibs.  A  smaller 


MANUFACTURE  OF  PLASTERS. 


35 


nipper,  weighing  8100  Ibs.  and  with  a  36"X12"  belt  pulley,  is  quoted 
as  having  a  capacity  of  10  to  14  tons  per  hour,  and  is  listed  at  $550. 

The  " nipper"  is  usually  followed  by  the  " cracker"  (Fig.  6),  which 
is  a  heavy  machine  of  the  familiar  toothed  spindle  type.    A  cracker 


FIG.  6. — Cracker  for  intermediate  reduction.     (Buttcrworth  &  Lowe.) 

weighing  8000  Ibs.  has  a  capacity  of  12  to  15  tons  per  hour,  and  is  listed 
at  $850. 

For  the  final  reduction  the  Stedman  disintegrator,  Sturtevant  rock- 
emery  mill,  or  ordinary  buhrstones  are  generally  used.  The  last  two 
machines  are  described  in  a  later  section  of  this  volume  (pp.  239,  240),  as 
they  are  quite  extensively  used  in  grinding  natural-cement  clinker. 


36 


CEMENTS,  LIMES,  AND  PLASTERS. 


The  Stedman  disintegrator  (Fig.  7)  is  composed  essentially  of  totu 
concentrically  placed  cages,  formed  of  steel  bars.  Of  these  cages,  the 
first  and  third  revolve  in  one  direction,  the  second  and  fourth  in  the 
opposite.  The  material  to  be  crushed  is  fed  into  a  hopper  which  dis- 
charges it  at'  the  center  of  the  cages.  The  gypsum  lumps  are  struck 


FIG.  7. — Stedman  disintegrator,  50-inch,  heavy  pattern;  open  and  slid  apart. 

by  the  bars  of  the  inner  cage,  and  thrown  outward  at  high  velocity. 
The  bars  of  the  second  cage,  revolving  in  the  opposite  direction,  strike 
them  with  a  blow  of  double  force,  and  this  operation  is  repeated  by  the 
bars  of  the  third  and  fourth  cages  in  succession. 

TABLE  5. 
SIZES,  CAPACITY,  ETC.,  OF  STEDMAN  DISINTEGRATORS. 


Size. 

Horse- 
power. 

Capacity  in  10 
Hours. 

Price. 

Weight, 
Lbs. 

30-inch  disint 
36-  " 

sgrator,  heavy  patt 

ern 

• 

6-9 
12-18 

8t 
18 

o  10  to 
25 

ns 

$300.00 
450.00 

3,000 
5,500 

42-  ". 

light 

12-18 

20 

30 

500.00 

6,000 

40-  " 

heavy       ' 

, 

20-25 

25 

35 

COO.  CO 

10,000 

44-  " 

i                 (i           i 

• 

30-35 

40 

50 

700.00 

12,000 

50^  " 

t                 K           i 

35-45 

60 

75 

900.00 

15,000 

MANUFACTURE  OF  PLASTERS. 


37 


After  being  reduced  as  alcove  described,  the  gypsum  is  calcined. 
Usually  it  is  necessary  to  regrind  some  of  the  product  which  comes  from 
the  kettles;  and  this  may  be  accomplished  in  any  of  the  fine  grinders 
above  noted. 

When  the  rotary  process  is  used,  it  is  customary  not  to  pulverize  the 
material  until  after  calcining.  As  calcined  plaster  is  much  easier  to 
grind  than  crude  gypsum,  a  considerable  saving  in  power  and  repairs 
is  effected  by  this  difference  in  practice. 


FIG.  8. — Stedman  disintegrator,  showing  cage  construction. 

Calcining  in  ovens. — In  the  manufacture  of  the  higher  grades  of 
plaster  of  Paris  it  is  necessary  that  the  material  should  be  calcined 
with  extreme  uniformity  and  at  exactly  the  proper  temperature.  This 
uniformity  in  burning  is  attainable  in  ovens,  though  the  process  is 
necessarily  expensive  in  fuel  and  labor.  For  these  reasons  the  oven 
process  has  not  been  used  in  the  tJnited  States,  though  it  still  persists 
in  Europe  for  certain  grades  of  plasters. 

Calcining  in  kettles. — The  favorite  process  in  the  United  States, 
particularly  in  the  plaster-plants  of  the  Middle  West,  is  that  in  which 
the  calcination  is  effected  in  kettles.  As  noted  later  in  discussing 
continuous  calcining  processes  (pp.  46-50)  the  kettle  process  is  slow, 
low  m  output,  and  expensive  in  fuel.  For  these  reasons  it  will  probably 
disappear  as  the  continuous  rotary  calciner  becomes  perfected;  but 
at  present  it  is  still  used  in  the  majority  of  American  plaster-plants. 
The  statements  above  should  not  be  construed  as  a  too  sweeping  con- 


38 


CEMENTS,  LIMES,  AND  PLASTERS. 


demnation   of   the  kettle  process,  for  that  process  is  undoubtedly  far 
superior  in  economy  to  its  European  progenitor,  the  oven  process. 


FIG.  1. 


FIG.  2. 


Section  on  C-D,  Fig.  1 


Section  on  A-B,  Fig.  2. 


FIG.  9.— Construction  and  setting  of  gypsum-kettles. 
(Trans.  Am.  Inst.  Min.  Engrs.) 

The  following  description  of  the  process  of  calcining  plaster  in  kettles 
is  abstracted,  in  large  part,  from  an  admirable  paper  *  by  Wilkinson. 
In  this  process  the  gypsum  is  ground,  and  charged  into  cylindrical 


*  Trans.  Am.  Inst.  Mining  Engineers,  vol.  27,  pp   514  et  seq. 


MANUFACTURE  OF  PLASTERS. 


39 


"kettles".     Heat  is  applied  both  at  the  bottom  of  the  kettle  and  by 
flues  passing  entirely  through  the  cylinder. 

A  heavy  stone  or  brick  masonry  support  is  built  for  the  kettle,  in- 
closing a  fire-space  in  the  form  of  an  inverted  cone  about  4  feet  high. 
At  the  top  of  this  cone  a  cast-iron  flanged  ring  is  set  in  the  masonry. 


FIG.  10. — Four-flue  kettle,  with  accessories,  dismounted.     (Butterworth  &  Lowe.) 

On  this  flange  is  placed  the  "kettle-bottom",  which  is  an  iron  casting, 
concavo-convex  in  shape,  a  little  less  than  8  or  10  feet  in  diameter, 
with  the  convexity  placed  upward,  the  rise  being  1  foot.  This  bottom 
has  a  thickness  of  f  inch  at  the  edges  and  4  inches  at  the  crown.  Kettle- 
bottoms  must  be  made  of  the  best  scrap-iron,  as  ordinary  scrap-iron  does 
not  last  as  long  as  pig.  Sheet  steel  has  been  tried,  but  does  not  serve 
as  well  as  the  best  scrap.  "The  life  of  a  kettle-bottom  is  terminated 
by  cracking.  The  cracks  can  be  calked  with  asbestos  cement,  but 
the  expense  of  stoppage  and  repairing  soon  overcomes  the  saving." 


40 


CEMENTS,  LIMES,  AND  PLASTERS. 


Within  the  past  few  years  sectional  kettle-bottoms  have  been  in- 
troduced quite  extensively.  A  kettle  of  this  type  is  shown  in  Fig.  11, 
in  which  the  kettle-bottom  is  composed  of  a  central  circular  section 
and  six  other  sections  fitting  around  it.  These  sections  are  made  of 
cast  iron.  The  principal  merit  of  this  design  is  that  in  case  any  section 
of  the  kettle-bottom  burns  out,  it  can  be  replaced  without  disturbing 
the  kettle  or  brickwork.  <i 


FIG.  11. — Kettle  with  sectional  bottom.     (Des  Moines  Mfg.  Co.) 

The  kettle,  which  is  placed  on  the  kettle-bottom,  is  of  boiler  iron 
f  to  f  inch  thick,  and  is  commonly  8  to  10  feet  in  diameter  and  6  to 
8  feet  deep.  Such  a  kettle  holds  about  7  to  12  tons  of  raw  material, 
producing  from  5^  to  10  tons  of  plaster.  The  kettle  has  two  or  four 
flues  12  inches  in  diameter,  placed  horizontally  about  8  inches  above 
the  crown  of  the  kettle-bottom  and  separated  externally  about  6  inches. 
After  the  kettle  has  been  set,  brick  masonry  is  erected  around  it,  gradu- 
ally converging  at  the  top  to  meet  the  top  rim  of  the  kettle.  The 
first  floor  of  the  mill  is  usually  built  around  the  kettle  about  a  foot 


MANUFACTURE  OF  PLASTERS.  41 

from  the  top,  sometimes  level  with  the  top,  to  facilitate  shoveling  the 
raw  material  into  the  kettle,  and  the  kettle  with  its  supports  is  in  the 
basement,  with  storage  room  for  fuel  conveniently  arranged  in  front 
of  the  kettle.  Ports  are  made  through  the  side  of  the  base  ring,  and 
the  heat  from  the  furnace  is  deflected  by  bridges  around  the  surface 
of  the  kettle,  so  that  the  heat  may  cover  every  part  of  the  kettle,  pass 
through  the  flues,  and  finally  make  exit  through  a  regular  stack. 

At  the  top  the  kettle  is  covered  with  a  sheet-iron  cap  having  a  mov- 
able door,  through  which  the  raw  material  is  introduced,  usually  by 
a  chute  fed  by  an  elevator. 

The  shipping- weight  of  an  8-foot  kettle  is  about  15,000  Ibs.,  and 
of  a  10-foot  kettle  about  18,500  Ibs.  Their  list  prices  are  about  $1200 
and  S16CO,  respectively. 

The  kettles  are  usually  arranged  in  line  and  worked  in  pairs,  with 
one  feeding  chute  and  one  pit  for  calcined  material  for  each  pair.  It 
is  necessary  that  the  material  in  the  kettle  be  kept  constantly  agitated, 
and  for  this  purpose  a  line  shaft  carrying  a  1-inch  vertical  pinion-wheel 
runs  over  the  kettles  and  a  4-inch  vertical  shaft  with  a  5-inch  hori- 
zontal crown-wheel  runs  from  this  to  the  bottom  of  each  kettle,  being 
supported  by  a  saddle  placed  between  the  flues.  At  the  bottom  of 
the  vertical  shaft  a  curved  cross  is  attached,  to  which  are  affixed  movable 
teeth  with  paddles,  run  at  15  revolutions  per  minute,  which  are  so 
adjusted  as  to  throw  the  material  from  the  periphery  to  the  center. 
From  10  to  25  H.P.  are  required  to  run  one  agitator.  Should  the  agita- 
tion stop,  or  the  teeth  become  broken,  the  material  settles  down  on 
the  bottom,  and,  owing  to  the  intense  heat,  the  bottom  is  almost  in- 
stantly melted  through.  The  material,  which  when  hot  is  very  fluid, 
runs  through  like  water  and  quenches  the  fire.  Stoppage  of  the  agita- 
tion can  usually  be  detected  by  the  calciner,  who  stands  above  and  is 
supposed  to  watch  the  process  of  calcination  constantly. 

In  burning  plaster  of  Paris  the  temperature  does  not  exceed  340°  F., 
but  when  gypsite  (gypsum  earth)  is  used  a  higher  temperature  is  re- 
r  uired,  averaging  close  to  396°  F.,  probably  owing  to  the  foreign  matters 
included  in  the  gypsite. 

In  starting  a  kettle,  the  heat  is  gradually  applied,  and  the  crude  ma- 
terial is  gradually  fed  in  and  constantly  agitated.  This  process  is  slow  and 
requires  some  length  of  time,  owing  to  the  vast  amount  of  mechanically 
held  water  which  must  be  evaporated  when  the  wet  gypsum  earths 
are  used.  Material  is  gradually  added  until  the  kettle  is  full,  and  as  the 
temperature  rises  the  contents  boil  violently,  much  like  water,  at  220°- 
230°  F.  (105°-110°  C.).  When  the  mechanically  held  water  is  evaporated 


42 


CEMENTS,  LIMES,  AND  PLASTERS. 


MANUFACTURE  OF  PLASTERS.         -  -        43 

the  contents  c.f  the  kettle  settle.  Further  heating,  however,  brings  on 
boiling  again,  at  about  290°  F.  (=143°  C.),  part  of  the  water  of  combin- 
ation being  now  driven  off.  The  point  at  which  the  process  is  complete, 
340°-396°  F.,  is  known  to  the  expert  calciner  by  the  manner  in  which 
the  material  boils  and  by  its  general  appearance,  and  at  the  proper 
moment  the  calciner  allows  the  charge  to  blow  out  through  a  small 
gate  at  the  bottom  and  in  the  side  of  the  kettle,  controlled  by  a  lever. 
In  plaster-of-Paris  plants  thermometers  are  commonly  used  to  govern 
the  temperature  exactly,  but  in  gypsite  plants,  whose  raw  material  is 
not  so  uniform  in  composition,  the  proper  point  varies  slightly  and  is 
usually  best  known  by  an  experienced  calciner. 

The  escaping  steam  is  let  off  by  means  of  a  stack  let  into  the  sheet- 
iron  cover  of  the  kettle  parallel  with  the  smoke-stack,  and  this  stack 
contains  near  its  base  a  separator  similar  to  the  steam-separators,  for 
the  purpose  of  retaining  the  plaster-dust.  It  has  been  found  by  raising 
the  iron  cpver  about  18  inches  and  putting  on  proper  sides,  that  it 
furnishes  a  chamber  above  the  boiling  material  and  greatly  assists 
the  escape  of  the  steam  from  it. 

From  the  kettle  the  hot  material  runs  like  water  into  a  fire-proof 
pit.  The  kettles  are  usually  run  in  couples  so  that  one  pit  will  do  for 
two  kettles ;  and  one  chute  will  do  for  two  kettles  in  filling,  as  the  kettles 
are  run  at  slightly  different  periods.  Each  kettle  contains  a  charge  of  about 
five  tons  of  manufactured  material,  and  requires  from  two  to  three  hours 
to  calcine  properly.  After  cooling  slightly,  the  manufactured  material  is- 
elevated  into  a  revolving  screen,  which  separates  all  small  particles  and 
foreign  matter  and  renders  the  product  uniform.  The  screenings  which 
Usually  amount  to  from  ^  to  1  per  cent  only  are  sent  back  to  buhrstone  and 
reground.  It  is  usual  to  have  a  series  of  screw-conveyors  and  elevators 
both  in  front  of  and  behind  the  screen,  so  as  to  mix  the  material  thor- 
oughly. Owing  to  the  temperature  of  the  material,  all  conveyors, 
elevators,  and  interior  linings  must  be  of  metal,  and  the  screen  is  made 
of  wire  cloth.  From  the  screen  the  material  is  conveyed  to  the  storage- 
bins  (which  are  usually  arranged  to  hold  100  or  200  tons),  of  which  there 
are  several,  so  as  to  separate,  if  desired,  the  runs  of  different  days.  The 
material  is  usually  allowed  to  fall  from  a  screw  at  the  top  of  the  building, 
first,  that  it  may  spread  out  and  let  the  different  portions  mix  thor- 
oughly, and,  secondly,  that  it  may  cool  in  passing  through  the  air. 

Temperature  and  water  determinations  made  by  Slosson  and  Moudy 
during  an  actual  run  of  the  Laramie  (Wyo.)  plaster-plant  are  given 
in  the  following  table.  The  kettle  used  carried  a  charge  of  about  five 
Ions,  and  the  run  was  completed  in  about  three  hours.  As  shown  by 


44 


CEMENTS/LIMES, 


PLASTERS. 


the  water  determinations  the  raw  material  (gypsum  earth)  carried  a 
very  large  percentage  of  moisture  in  addition  to  its  necessary  water 
of  crystallization.  An  analysis  of  the  finished  product,  given  below, 
shows  that  it  is  made  from  a  very  impure  gypsum: 

ANALYSIS  OF  LARAMIE  PLASTER. 

'Lime  sulphate  (CaSO4).  ,  . . . 73.73% 

Lime  carbonate  (CaC03) 7 .86% 

Lime  (CaO) f. 2.35% 

Magnesium  carbonate  (MgCO3) 3 . 04% 

Silica  (Si02) 5.50% 

Alumina  (A12O3) . ,  .  0.59% 

Water  (H20) '.  6.93% 

Inspection  of  this  analysis  also  proves  that  the  plaster  still  carries 
a  little  more  water  than  is  theoretically  correct.  If  these  various  points 
be  borne  in  mind,  the  temperature  determinations  given  below  will 
prove  of  value. 

TABLE  6. 
TEMPERATURES  IN  CEMENT-PLASTER  MANUFACTURE. 


Time. 

Temperature. 

Pounds  Water 
Contained  per 
100  Pounds 
CaSO4. 

Percentage 
Water 
Contained. 

Remarks. 

Hrs.  Min. 
0        0 
2        0 
2     20 
2     30 
2     50 

65°  F. 
310°  F. 
320°  F. 
340°  F. 
390°  F. 

59.93  Ibs. 
16.85    " 
13.66    " 
12.41     " 
9.17    " 

32.02% 

11.69% 
9.69% 

8.34% 
6.75% 

Kettle  charged. 
Kettle  full. 
Charge  boiling. 
End  of  first  boil. 
Charge  dumped. 

Actual  equipment  of  kettle-process  plants. — Plans  of  two  kettle- 
process  plants  are  given  in  Figs.  12  and  13.  The  following  data,  giving 
the  actual  equipments  of  a  number  of  plaster-plants  in  the  United  States, 
will  serve  to  give'  a  good  idea  of  the  relation  of  crushing  machinery  to 
number  of  kettles: 

Plant  No.  1.       (a)  2  Butterworth  &  Lowe  nippers. 
(6)   2  Butterworth  &  Lowe  crackers. 

(c)  4  runs  of  4-foot  buhrstones  and  1  Sturtevant  vertical  rock  emery 

mill; 

(d)  4  10-foot  kettles  holding  10  tons  each. 

(e)  8  runs  of  small  buhrstones  for  regrinding  finer  grades  of  plaster. 
Plant  No.  2.       (a)  1  nipper. 

(fr)   1  cracker. 

(c)  4  runs  of  buhrstones. 

(d)  3  10-foot  kettles. 


MANUFACTURE  OF  PLASTERS. 


Plant  No.  3.       (a)  1  Godfrey  double  nipper  and  cracker. 
(6)   3  Sturtevant  vertical  rock  emery  mills. 

(c)  3  10-foot  kettles. 

(d)  2  runs  of  small  buhrs  for  regrinding. 
Plant  No.  4.       (a)  1  nipper. 

(b)  1  cracker^ 

(c)  2  runs  of  buhrstones  and  1  Sturtevant  vertical  rock  emery  mill 

(d)  2  10-foot  kettles. 

(e)  3  runs  of  buhrstones  for  regrinding. 


Prive  Shaft  for  loading  pebble 
in  R.R.  care 


and  Cooling  "Bins 


R.R.  Track, 


Illllli 


"^Transformers 

FIRST  FLOOR 


SECOND  FLOOR 


THIRD  FLOOR, 

FIG.  13. — Plan  of  Electric  Plaster  Co.'s  mill,  Blue  Rapids,  Kansas. 
(Engineering  and  Mining  Journal.) 

Plant  No.  5.       (a)  1  nipper. 

(6)  1  cracker. 

(c)  2  runs  of  buhrstones. 

(d)  1  10-foot  kettle. 


46  CEMENTS,  LIMES,  AND  PLASTERS. 

Plant  No.  6.       (a)  1  nipper. 
(6)    1  cracker. 

(c)  4  runs  of  buhrstones. 

(d)  2  8-foot  and  1  10-foot  kettles. 
Plant  No.  7.       (a)   1  Stedman  disintegrator. 

(b)  3  runs  of  buhrstones. 

(c)  3  10-foot  kettles. 

(d)  2  runs  of  buhrstones  for  regrinding. 
Plant  No.  8.       (a)   1  Butterworth  &  Lowe  Ettpper. 

(6)  1  cracker. 

(c)  4  runs  of  buhrstones. 

(d)  2  8-foot  kettles. 

(e)  1  run  of  buhrstones  for  regrinding. 
Plant  No.  9.       (a)  1  Blake  crusher. 

(6)    1  cracker. 

(c)  5  runs  of  buhrstones. 

(d)  5  10-foot  kettles. 
Plant  No.  10.     (a)   1  Blake  crusher. 

(b)  2  runs  of  buhrstones. 

(c)  2  10-foot  kettles. 

Rotary- cylinder  processes. — It  will  probably  have  been  noted  by 
the  reader  that  both  of  the  plaster-calcining  processes  previously  de- 
scribed are  discontinuous  in  operation  and  consequently  expensive 
in  both  time  and  fuel.  These  defects  of  the  oven  and  kettle  processes 
are  avoided  in  the  rotary  cylinder  processes  now  coming  into  use  in 
both  America  and  Europe.  In  the  United  States  a  rotary  process 
has  been  adopted  in  a  number  of  New  York  .plaster-plants,  and  has 
been  in  practical  operation  for  a  sufficiently  long  time  to  demonstrate 
its  superiority  crver  the  kettle  process.  In  Europe,  to  judge  from  a 
recent  description  of  the  German  plaster  industry,  rotary  plaster  cal- 
ciners  have  been  used  for  a  number  of  years  and  have  proven  entirely 
satisfactory. 

Cummer  system. — Most  of  the  American  plants  using  the  rotary  cal- 
cination process  have  been  equipped  on  the  system  devised  by  the 
F.  D.  Cummer  &  Son  Co.,  of  Cleveland,  Ohio. 

The  plan  of  a  New  York  plant  using  this  process  is  shown  in  Fig.  14. 
This  plant  uses  rock  gypsum,  and  .with  the  equipment  shown  produces 
50  tons  of  calcined  plaster  per  day  of  eleven  hours,  six  men  being  re- 
quired to  operate  the  mill.  The  rock  coming  direct  from  the  mine  is 
delivered  into  the  jaw  crusher  A,  where  it  is  reduced  so  as  to  pass  a 
2^-inch  ring.  Elevator  B  carries  the  crushed  rock  from  crusher  to 
screen  C,  which  separates  all  material  that  will  pass  a  1-inch  ring.  The 
tailings  from  the  screen  pass  through  the  rolls  D  and  meet  with  the 
material  which  passes  through  the  screen.  All  of  the  material  now 


MANUFACTURE  OF  PLASTERS. 


47 


crushed  to  pass  a  1-inch  ring  is  carried  by  elevator  E  and  delivered 
into  bin  F.  From  this  bin  the  crushed  rock  is  fed  mechanically  by 
feeder  H  into  the  Cummer  rotary  calciner  G.  In  this  machine  most  of 
the  free  moisture  is  eliminated,  and  the  process  of  calcining  also  carried 
forward  toward  completion.  The  material  delivered  from  the  rotary 
calciner  is  steaming  and  heated  to  from  350°  to  400°  F.,  the  exact  tem- 


FIG.  14. — Plan  of  plaster-mill  equipped  on  Cummer  rotary  calcining  system, 
perature  depending  upon  the  nature  and  density  of  the  rock.  Elevator 
/  carries  the  product  from  the  calciner  to  the  Cummer  calcinirig-bins  K, 
where  it  is  allowed  to  remain  about  thirty-six  hours.  Dtrring_this  time 
the  resident  heat  in  the  material  completes  the  process  of  calcination, 
and  the  material  is  cooled,  ready  for  the  mills.  The  now  calcined  mate- 
rial is  mechanically  discharged  from  the  bins  into  elevator  M,  which 
carries  it  into  the  small  bins  situated  over  the  mills  0.  From  the  mills 
the  conveyor  R  delivers  the  pulverized  material  into  screen  S.  The 
finished  material  is  sacked  at  T.  The  tailings  from  the  screen  are  spouted 
into  elevator  M  and  returned  to  the  mills. 

The  calcining-bins  noted  above  are  an  integral  part  of  the  Cummer 
process.  These  bins  are  built  preferably  of  brick  and  are  lined  with 
paving  brick,  so  that  they  will  not  absorb  the  moisture  given  off  from 
the  gypsum  rock  during  calcination.  Three  bins  are  required  for  each 
plant,  and  the  capacity  of  each  bin  is  equal  to  the  daily  output  of  the 
plant.  By  the  use  of  three  bins  a  continuous  process  is  obtained.  One 
bin  is  being  discharged  of  its  cooled  calcined  material  while  the  process 


48 


CEMENTS,  LIMES,  AND  PLASTERS. 


of  calcination  is  being  completed  on  the  material,  in  the  second  bin, 
and  the  third  bin  is  being  filled  with  material  from  the  rotary  calcintr. 
These  bins  are  so  constructed  that  the  material  in  process  of  calcination 
is  thoroughly  ventilated,  which  allows  the  heat  carried  by  the  material 
from  the  rotary  calciner  to  rapidly  disseminate  itself  through  the  mass 
and  complete  the  calcining  process.  While  the  resident  heat  in  the 
material- is  acting  upon  it,  practically  no  circulation  of  air  through  the 
material  is  allowed,  but  as  soon'  as  the  ^process  of  calcining  is  completed, 
air  at  atmospheric  temperatures  is,  freely  circulated  through  the  mass 
and  the  calcined  gypsum  is  rapidly  cooled.  Each  bin  is  equipped  with 
a  simple  device  which  mechanically  discharges  the immaterial  regularly 
and  at  any  speed  desired. 

A  dust-chamber  located  above  the  rotary  calciner  catches  the  most 
finely  ground  plaster,  which  is  marketed  for  dental  plaster  and  other 
special  purposes. 

The  Cummer  rotary  calciner  is  shown  in  section  in  Fig.  15.  Its 
operation  is  as  follows:  • 


FIG.  15. — Cummer  rotary  plaster- calciner. 

The  gypsum  rock  is  fed  through  a  hopper,  F,  into  a  cylinder  set 
on  a  slight  incline  rotating  on  trunnioned  bearings  within  a  brick  chamber. 
The  material  passes  slowly  down  the  cylinder  (owing  to  its  inclination 
and  rotation),  being  thrown  about  by  lifting-blades  attached  to  the 
inside  of  the  cylinder.  It  is  discharged  at  K,  having  been  subjected 
during  its  passage  to  the  heated  fuel  gases,  whose  admission  and  handling 
will  next  be  described. 

The  hot  gases  from  the  furnace  are  drawn  by  the  fan  G  into  the 
brick  chamber  surrounding  the  cylinder.  Cold  air  is  introduced  through 
the  registers  E  and  0  and  mixed  with  the  furnace  gases  in  such  propor- 
tions as  to  give  the  desired  temperature.  These  gases  are  drawn  into 
the  cylinder  through  the  hooded  openings  J  and  pass  through  it  in  a 


MANUFACTURE  OF  PLASTERS.  49 

direction  opposite  to  that  taken  by  the  wet  material.     Pyrometers  for 
control  of  the  temperature  may  be  placed  in  the  holes  H  in  the  masonry. 

Mannheim  system. — A  German  plaster-plant  using  a  rotary  calcining 
system  has  recently  been  described  *  in  considerable  detail,  and  seems 
worthy  of  attention  as  presenting  certain  interesting  differences  to  the 
system  discussed  above.  The  mill  in  question  is  that  of  the  Rhenish 
Gypsum  Company,  located  at  Mannheim,  in  Rhenish  Prussia. 

The  crude  gypsum  is  passed  through  crushers  and  nippers,  but  is 
not  finely  powdered  previous  to  calcining.  "When  the  material  comes 
from  the  crushers  and  nippers  it  varies  in  size  from  the  finest  powder 
to  fragments  as  large  as  an  ordinary  hickory-nut.  Varying  thus  in 
size,  the  material  goes  directly  to  the  calciner." 

"The  calciner  consists  of  a  fire-box  with  an  automatic  stoker,  which 
is  placed  in  front  of  and  connected  with  a  chamber  containing  a  rotating 
cylinder.  Above  this  cylinder  is  a  chamber  called  the  'forewarmer', 
through  which  a  spiral  conveyor  passes  from  end  to  end.  A  pipe  leads 
from  the  rotating  cylinder  to  the  forewarmer  and  connects  at  the  other 
end  with  the  chimney.  Connected  with  the  fire-box  is  a  fan  by  which 
a  forced  draft  is  secured.  The  fire-box  is  heated  to  a  high  temperature, 
and  the  fuel  gases,  forced  by  the  fan,  pass  through  the  rotating  cylinder 
and  then  through  the  forewarmer.  The  crude  gypsum  is  carried  by 
bucket  elevators  from  the  crushers  to  a  bin  above  the  calciner  and 
thence  it  flows  by  gravity  into  the  forewarmer,  through  which  it  is 
carried  by  the  spiral  conveyor.  It  then  falls  directly  into  the  rotating 
calciner  below.  Shelves  or  buckets  on  the  inside  of  this  cylinder  pick 
up  the  material  and  elevate  it  as  the  cylinder  rotates.  When  the  material 
nears  the  top  the  slant  of  the  shelves  is  so  great  that  it  falls  again 
to  the  bottom.  The  strong  draft  of  hot  air  passing  through  the  cylinder 
from  the  fire-box  strikes  the  gypsum  as  it  falls  and  moves  the  fragments 
toward  the  rear  with  a  velocity  directly  f  proportional  to  their  size. 
The  coarser  material  moves  much  more  deliberately  and  thus  is  exposed 
to  the  heat  longer  than  the  finer  and  more  readily  calcined  particles. 
In  this  way,  though  the  material  entering  the  rotating  cylinder  varies 
greatly  in  fineness,  the  coarser  material  is  sufficiently  calcined  and 
the  finer  is  not  overburned.  All  of  the  heat  has  not  been  exhausted 
in  passing  through  the  rotary  cylinder  and  this  is  for  the  most  part 
saved  by  forcing  the  air,  after  it  leaves  the  cylinder,  through  the  fore- 
warmer.  In  this  process  the  heat  is  so  completely  utilized  that  the 
air  and  furnace  gases  pass  to  the  chimney  with  a  temperature  of  only 

*  Wilder,  F.  A.     Vol.  12,  Iowa  Geological  Survey,  pp.  213-216. 
t  Evident  misprint  for  "inversely".     E.  C.  E. 


50 


CEMENTS,  LIMES,  AND  PLASTERS. 


80°  C.  Between  the  forewarmer  and  the  chimney  the  dust-chamber  is 
located.  Here  all  of  the  finer  particles  are  allowed  to  settle  and  the 
air  passes  on  to  the  chimney  practically  free  from  dust.  To  calcine 
one  ton  of  gypsum  by  this  method  experience  has  demonstrated  that 
on  the  average  only  100  Ibs.  of  rather  inferior  bituminous  coal  are  required. 
An  automatic  recorder  indicates  constantly  the  heat  of  the  rotary 
cylinder,  and  this,  with  the  mechanical  stoker,  insures  an  even  tempera- 
ture during  the  entire  process  of  calcining.  From  the  rotary  cylinder 
the  gypsum  is  again  elevated  to  the  floor  above  and  passes  through  a 
spiral  conveyor  which  is  surrounded  by  a  water-jacket.  Here  the  plaster 
is  cooled  and  passes  on  to  the  sieves.  That  portion  of  the  plaster  which 
does  not  need  further  grinding  is  separated  by  the  sieves  and  the  rest 
goes  to  the  vertical  mills." 

The  process  shows  economy  in  fuel,  labor,  and  powrer  over  the  older 
methods.  On  the  other  hand,  "a  limited  amount  of  soot  settles  in  the 
plaster,  and  it  is  slightly  coated  with  calcium  sulphide,  due  to  the  reac- 
tion on  the  gypsum  of  the  sulphur  present  in  the  coal.  For  ordinary 
building  purposes,  however,  these  do  not  injure  the  plaster." 

Addition  of  retarders  and  accelerators. — It  is  now  the  common  prac- 
tice for  plaster  manufacturers  to  add  retarders  to  their  product,  in  order 
to  prevent  its  setting  too  rapidly  for  the  convenience  of  the  workman. 
The  general  discussion  of  the  character  and  effects  of  retarders  and 
accelerators  can  best  be  taken  up  in  the  following  chapter.  At  present 
it  is  only  necessary  to  state  that  the  retarder  is  best  added  after  the 
plaster  is  entirely  cool,  as  otherwise  most  retarders  will  melt  and  form 
lumps  in  the  plaster.  From  2  to  15  Ibs.  of  retarder  are  usually  added 
to  the  ton  of  plaster,  and  the  mixing  is  generally  accomplished  in  a 
Broughton  mixer  or  some  similar  device. 

The  following  data  relative  to  the  Broughton  mixer,  which  is  shown  in 
Fig.  16,  are  taken  from  the  catalogue  of  the  Des  Moines  Manufacturing 
and  Supply  Company,  and  will  serve  to  give  some  idea  of  the  capacity, 
cost,  etc.,  of  the  machine. 

TABLE  7. 
SIZES,  CAPACITY,  ETC.,  OF  BROUGHTON  MIXERS. 


Style               

A-l 

A 

B-l 

B-2 

B-3 

Capacity  of  hopper  Ibs 

1800-2000 

1000-1400 

600 

500 

250 

Bag-holders  number 

6 

5 

Product  per  day,  10  hours,  tons.  .  .  . 
Size  of  pulleys,  inches           ........ 

60-90 
30X12 

35-50 

24X8 

35 

24X8 

15 

20X6 

71 
16X4 

Revolutions  per  minute  

150 

150 

175 

160 

160 

Horse-power  required 

18-22 

8-12 

8-12 

5  7 

3  1 

Shipping  weight  Ibs                  .  . 

7300 

4750 

3800 

2300 

List  price  

$675 

$450 

$400 

$300 

$250 

MANUFACTURE  OF  PLASTERS. 


51 


Wall-plaster.— An  ordinary  wall-plaster  contains,  in  addition  to 
whatever  retarder  may  be  necessary,  a  certain  percentage  of  finely  picked 
hair  or  other  fiber.  In  order  to  insure  thorough  mixing  with  the  plaster 
the  hair  is  first  picked  to  pieces  in  a  hair-picker,  whi'ch  is  usually  a  device 
of  the  toothed-drum  type  revolving  at  high  speed.  The  hair  is  then 


FIG.  16. — Broughton  mixer. 
(Des  Moines  Mfg.  Co.) 


FIG.  17. — Hair-picker. 


added  to  the  plaster  in  the  proportions  of  H  to  3  Ibs.  hair  per  ton  of 
plaster  and  the  materials  are  fed  to  the  mixer. 

The  hair-picker  shown  in  Fig.  17  is  run  at  a  speed  of  600  revolutions 
per  minute  and  will  disintegrate  5  to  6  bales  of  hair  per  hour.  It  is 
listed  at  $75. 

Wood  fiber  is  often  used  as  a  substitute  for  hair,  the  cottonwood 
giving  a  particularly  serviceable  fiber  for  this  use.  The  log  is  barked 
by  hand  or  machine  and  cut  into  sections  20  inches  or  so  in  length. 
These  are  then  placed  in  a  fiber  machine,  which  will  usually  take  pieces 
6  to  15  inches  in  diameter.  The  fiber  is  torn  off  by  revolving  toothed 


52  CEMENTS,  LIMES,  AND   PLASTERS. 

cylinders  between  which  the  log  is  pressed.  One  machine  will  cut 
enough  fiber  in  nine  or  ten  hours  to  make  30  to  40  tons  of  plaster.  The 
usual  mix  consists  of  75  to  150  Ibs.  wood  fiber  to  one  ton  of  calcined 
plaster. 

Plasters  are  usually  packed  in  jute  sacks  containing  100  Ibs.  or  in 
paper  bags  containing  80  Ibs.  An  extra  charge  of  10  cents  is  com- 
monly made  for  each  jute  sack,  rebated  on  the  return  of  the  sack.  As 
the  sacks  may  cost  the  mill  4  to  6  cents  each,  any  sacks  not  returned 
furnish  a  fair  profit.  A  charge  of  50  cents  per  ton  of  plaster  is  usually 
made  for  packing  in  paper  bags,  which  are  not  returnable. 

Costs  of  plaster-manufacture. — An  estimate  of  the  cost  of  plaster- 
manufacture  at  Kansas  mills,  made  in  1897  by  G.  P.  Grimsley,*  follows. 

COST  OF  PLASTER-MANUFACTURE  PER  TON. 

Mining  costs. SO .  80 

Fuel  at  mill 0 . 30 

Labor  at  mill. 0 . 50 

Office  force  and  sales  agents 1 . 25 


Total  cost  of  plaster  per  ton $2 . 85 

Setting  aside  the  question  of  cost  of  "office  force  and  sales  agents", 
which  varies  greatly  in  different  mills,  the  estimate  given  above  appears 
to  the  writer  to  be  very  high  for  mining  costs,  rather  below  the  average 
for  fuel  costs,  and  about  the  maximum  for  labor.  The  following  esti- 
mates of  cost  of  manufacture  by  the  kettle  process  have,  therefore, 
been  prepared  as  giving,  in  the  writer's  opinion,  fairly  close  limiting 
values : 

Max.  Min.  Average. 

Mining  or  quarrying  2400  Ibs.  gypsum.  ...    $0 . 72         $0.12         $0 . 30 

Power  fuel  at  mill,  75  to  125  Ibs.  coal 0.19  0 . 05  0.10 

Kiln  fuel  at  mill,  225  to  325  Ibs.  coal 0 . 49  0.15  0 . 30 

Labor  at  mill. .  0.50  0.30  0.40 


Total  cost  per  ton  plaster  at  mill $1 . 90         $0 . 62         $1.10 

The  rotary  process  of  plaster  calcination  has  not  been  used  at  enough 
plants  to  give  accurate  limiting  figures  of  costs,  but  the  following  esti- 
mates are  believed  to  be  fairly  close: 

Max.  Min. 

Mining  or  quarrying  2400  Ibs.  gypsum.  ...   $0 . 72  $0 . 12 

Power  fuel  at  mill,  50  to  80  Ibs.  coal ....     0.12  0.04 

Kiln  fuel  at  mill,  150  to  200  Ibs.  coal 0 . 31  0 . 10 

Labor  at  mill 0.30  0.18 

Total $1.45  $0.44 

*  Mineral  Industry,  vol.  7,  p.  392. 


MANUFACTURE  OF  PLASTERS. 


53 


Analyses  of  gypsum  used  in  actual  practice. — The  following  analyses 
of  both  rock  gypsum  and  gypsite  (gypsum  earth),  taken  from  various 
sources,  will  be  fairly  representative  of  the  materials  used  for  plaster  at 
different  plants.  For  comparison  it  is  well  to  recollect  that  a  theoret- 
ically pure  gypsum  would  consist  of  lime  sulphate  79.10  per  cent,  water 
20.90  per  cent,  and  would  contain  no  silica,  alumina,  iron  oxide,  lime 
carbonate,  or  magnesium  carbonate. 

TABLE  8. 
ANALYSES  OF  ROCK  GYPSUM  USED  FOR  PLASTER. 


+ 

Silica 
(Si02). 

Alumina 
(A12O3)  and 
Iron  Oxide 
(Fe203). 

Lime 
Carbonate 
(CaC03). 

Magnesium 
Carbonate 
(MgCO3). 

Lime 
Sulphate 
(CaS04). 

Water 
(H20). 

1 

79.40 

20.30 

2 

6^35 

Q.  12 

6!io 

6^25 

78.73 

20.52 

3 

0.65 

0.17 

1.53 

0.39 

79.30 

18.84 

4 

0.40 

0.19 

0.25 

0.35 

78.10 

20.36 

5 

0.35 

0.12 

0.56 

0.57 

78.40 

19.96 

6 

1.18 

0.15 

0.36 

0.52 

78.04 

20.00 

7 

0.52 

0.26 

1.87 

2.06 

75.84 

19.47 

8 

0.34 

0.16 

1.68 

1.30 

76.98 

19.63 

9 

0.41 

0.29 

0.55 

0.61 

78.25 

19.70 

10 

0.55 

0.23 

0.86 

0.47 

78.11 

19.54 

11 

0.38 

0.16 

0.96 

77.81 

20.37 

12 

0.19 

0.10 

l!43 

0.34 

77.46 

20.46 

13 

0.05 

0.08 

0.11 

78.51 

20.96 

14 

n.  d. 

n.  d. 

n.'  d. 

n.  d. 

77.11 

19.00 

15 

tr. 

0.54 

n.  d. 

n.  d. 

76.26 

20.84 

16 

1.24 

0.50 

2.38 

.... 

77.19 

19.03 

17 

0.56 

tr. 

1.86 

77.77 

20.28 

18 

0.68 

0.16 

n.  d. 

n.'  d. 

78.08 

20.14 

19 

0.46 

0.29 

n.  d. 

n.  d. 

78.96 

20.00 

20 

0.91 

0.60 

n.  d 

n.  d. 

78.73 

19.70 

21 

0.10 

0.70 

.... 

79.26 

19.40 

22 

0.02 

0.55 

80.14 

19.07 

23 

0.49 

0.46 

77.94 

20.85 

24 

1.68 

1.95 

72.06 

21.30 

25 

0.10 

0.10 

78.55 

20.94 

26 

0.11 

i!o7 

.  .    . 

98.42 

20.43 

1.  Gypsum  Station,  Calif. 

2.  Blue  Rapids,  Kansas  }  used     at     Great 


3. 

4.  "         "  " 

5.  Dillon,  Kansas. 
6. 

7.  Hope,  Kansas. 


Western  Plas- 
ter-mill. 


13.  Alabaster,  Michigan,  used  at  Western 

Plaster  Works. 

14.  Grand  Rapids,  Mich 
15. 


Alabaster,  Mich. 
Near  Sandusky.  Ohio. 


10.  Solomon,  Kansas. 

11. 

12.  Medicine  Lodge,  Kansas. 


16. 

]7. 

18 

19 

20.      " 

21-24.  Saltville,  Virginia. 

25.  Hillsboro,  New  Brunswick. 

26.  Baddeck  Bay,  Nova  Scotia 


54 


CEMENTS,  LIMES,  AND  PLASTERS. 


TABLE  9. 
ANALYSES  *  OF  GYPSITE  (GYPSUM  EARTH)  USED  FOR  PLASTER. 


Silica 
(Si02). 

Alumina 
(A12O3)  and 
Iron  Oxide 
(Fe203). 

Lime 
Carbonate 
(CaC03). 

Magnesium 
Carbonate 
(MgC03). 

Lime 
Sulphate 
(CaS04). 

Water 
(H20). 

1 

10.67 

0.60 

"10;  21 

*      1  .  10 

59.46 

16.59 

2 

2.17 

0.24 

2.66 

0.95 

75.11 

19.40 

3 

2.31 

0.37 

11.71 

0.52 

67.91 

17.72 

4 

4.54 

0.54 

5.07 

0.59 

71.57 

17.82 

5 

13.50 

1.05 

7.50 

0.76 

6,0.27 

17.05 

6 

7  .65 

0.52 

8.11 

0.63 

64.72 

18.39 

-7— 

3.62 

-  0.45 

4.09 

0.34 

71.94 

19.87 

8 

15.08 

4).  44 

7.02 

CO  51 

17.46 

9 

10.23 

1.12 

11.77 

0.94 

58.75 

17.10 

10.. 

34.35 

4.11 

8.14 

10.52 

34.38 

8.50 

11 

9.73 

0.78 

4.32 

tr. 

68.29 

16.88 

12 

3.06 

0.34 

11.03 

0.90 

67.32 

17.24 

13 

4.25 

0.53 

3.56 

0.21 

69.51 

20.82 

14 

4.82 

0.79 

4.52 

0.34 

68.14 

-    20.41 

15 

15.76 

0.49 

5.14 

59.93 

18.64 

16 

8.78 

1.98 

7.25 

1.12 

58.25 

20.6^ 

17 

7.68 

0.89 

7.39 

1.76 

63.37 

17.77 

18 

11.78 

1.87 

7.37 

1.00 

59  .  56 

18.25 

19 

6.33 

0.53 

13.68 

0.88 

55.71 

19.23 

20 

5.14 

0.67 

7.36 

1.12 

66.64 

19.95 

21 

12.13 

0.99 

3.57 

0  88 

64.63 

16  7o 

22 

17.10 

2.04 

7.71 

1.24 

56.58 

15.16 

23 

3.18 

0.95 

6.18 

0.33 

69.70 

19.44 

24 

6.49 

1.04 

6.96 

0.27 

65.97 

18.56 

25 

17.95 

1.43 

n.  d. 

n.  d. 

61.00 

18.44 

*  The  analyses  in  this  table  are  mostly  by  Bailey  and  his  associates  and  are  quoted  from  vol. 
5,  Kansas  Geol.  Survey. 


Marlow,    Indian    Territory,    used    for 

' '  Royal ' '  brand  plaster. 
Mulvane,  Kansas. 
Burns,  Kansas. 

Tinkler,  Kansas,  used  at  Gypsum  City. 
Gypsum  City,  Kansas,  surface  of  bed, 

used  for  "Acme"  brand  plaster. 
Gypsum  City,   Kansas,  center  of  bed, 

used  for  "Acme''  brand  plaster. 
Gypsum   City,    Kansas,   average,   used 

for  "Acme"  brand  plaster. 
Gypsum    City,    Kansas,    quick-setting 

gypsite,    used    for    "Acme"    brand 

plaster. 
Longford,     Kansas,     used     by     Salina 

Cement   Plaster  Co. 
Salina,  Kansas. 

Rhoades,  Kansas. 

"      ,4  feet  from  surface. 


14.   Rhoades,  Kansas 


8  feet  from  surface. 


15.  bottom  of  bed. 

16.  average  of  1  acre. 

17.  average  of  8  samples 
2£-3£  feet  depth. 

18.  Rhoades,  Kansas    small  deposit. 

19.  material    very    slow 
setting. 

20.  Rhoades,  Kansas,  average    as    used   in 

plaster-plant. 

21.  Dillon,  Kansas,  used  by  Salina  Cement 

Plaster  Co. 

22.  Dillon,  Kansas,  used  by  Dillon  Cement 

Plaster  Co. 

23.  Dillon,  Kansas,  used  by  Dillon  Cement 

Plaster  Co. 

24.  Dillon,    Kansas,    used    for    "Agatite'* 

plaster. 

25.  Okarche,  Oklahoma. 


MANUFACTURE  OF  PLASTERS.  55 

Inspection  of  the  analyses  quoted  in  Tables  8  and  9  will  show  that 
the  rock  gypsum  used  at  plaster  plants  is  usually  very  pure.  Until 
very  recently  no  attempt  has  been  made  to  utilize  the  impure  gypsum 
rock  which  forms  such  a  large  proportion  of  the  New  York  deposits,, 
though  there  is  no  technologic  reason  for  not  using  it.  The  analyses 
of  gypsite  or  gypsum  earth,  on  the  other  hand,  are  mostly  representa- 
tive of  very  impure  materials,  carrying  large  percentages  of  sand,  clay,, 
and  fragments  of  limestone.  The  presence  of  these  impurities  in  the 
natural  raw  material  is  a  matter  of  technologic  importance,  for  the 
calcined  plaster  made  from  such  impure  materials  is  naturally  very 
slow  setting. 

References  on  plaster-manufacture.  —  The  following  papers  deal 
largely  with  the  manufacturing  side  of  the  gypsum  industry. 

Crane,  W.  R.     Mining  and  milling  of  gypsum  in  Kansas      Engineering  and 

Mining  Journal,  Nov.  9,  1901. 
Crane,  W    R.     The  gypsum  plaster  industry  of  Kansas.     Engineering  and. 

Mining  Journal,  vol.  77,  pp.  442-445.     1904. 
Grimsley  G.  P.,  and  Bailey,  E.  H.  S.     Special  report  on  gypsum  and  gypsum 

cement   plasters.      Vol.   5,   University   Geological   Survey  of  Kansas,. 

183   pp.   1899. 
Grimsley,  G.  P.     A  preliminary  report  on  the  gypsum  deposits  of  Michigan. 

Ann.  Rep.  Michigan  Geological  Survey  for  1902,  pp.  4-io.     1903. 
Parsons,  A.  L.     Recent  developments  in  the  gypsum  industry  in  New  York 

State.     20th  Ann.  Rep.  New  York  State  Geologist,  pp.  177-183.     1902, 
Slosson,  E.  E.,  and  Moudy,  R.  B.     The  Laramie  cement  plaster.     10th  Ann- 

Rep.  Wyoming  College  of  Agricultural  and  Mechanics. 
Wilder,  F.  A.     Geology  of  Webster  County,  Iowa.     Vol.  12,  Reports  Iowa 

Geological  Survey,  pp.  63-235.     1902. 
Wilder,  F.  A.     The  gypsum  industry  of  Germany.     Vol.   12,  Reports  Iowa 

Geological  Survey,  pp.  192-223.     1902. 

Wilder,  F.  A.     Present  and  future  of  the  American  gypsum  industry.     En- 
gineering and  Mining  Journal,  vol.  74,  pp.  276-278.     1902. 
Wilkinson,  P.     The  technology  of  cement  plaster.     Trans.  Amer.  Inst.  Mining 

Engrs.,  vol.  27,  pp.  508-519. 


CHAPTER  III. 
COMPOSITION,  PROPERTIES,  £ND  TESTS  OF  PLASTERS. 

IN  the  present  chapter  the  chemical  composition  and  physical  prop- 
erties of  plaster  of  Paris  and  cement  plasters  will  be  taken  up  in  the 
order  named. 

Chemical  Composition. 

Theoretical  composition. — A  theoretically  pure  plaster  of  Paris, 
being  a  definite  chemical  compound  (CaSC^+iH^O),  would  have  the 
composition:  lime  sulphate,  93.8  per  cent;  water,  6.2  per  cent.  This 
composition  is  approached  quite  closely  in  plasters  made  from  a  pure 
rock  gypsum. 

Cement  plasters,  as  has  been  described  on  earlier  pages,  can  be  made 
in  two  different  ways,  which  give  two  different  products  so  far  as  com- 
position is  concerned.  (1)  Cement  plasters  may  be  made  by  adding 
retarders  to  a  pure  plaster  of  Paris.  As  the  retarder  is  organic  matter 
and  rarely  amounts  to  over  1  per  cent  of  the  total  mass  the  resulting 
product  will  on  analysis  differ  very  little  from  the  plaster  of  Paris  of 
which  it  was  made.  (2)  Cement  plaster  may  also  be  made  by  burning 
an  impure  gypsum,  with  or  without  the  addition  of  retarder.  In  this 
case  analysis  would  show  the  presence  of  a  large  percentage  of  clayey 
matter,  etc.,  and  a  cement  plaster  of  this  type  will  therefore  have  a 
composition  very  different  from  that  of  a  pure  plaster  of  Paris.  Exam- 
ples of  both  these  types  will  be  found  in  Table  11,  opposite. 

Actual  composition  of  plaster  of  Paris. — The  composition  of  the  pure 
quick-setting  plasters  here  grouped  as  plaster  of  Paris,  as  these  plasters 
appear  in  commerce,  is  shown  by  the  following  table  (10)  of  represen- 
tative analyses. 

Actual  composition  of  cement  plasters.  —  As  noted  earlier,  a 
cement  plaster  when  ready  for  sale  differs  from  the  gypsum  of  which 
it  was  made  only  in  the  loss  of  water  and  the  addition  of  a  very  small 
proportion  (-}5%  to  1%)  of  retarder.  The  difference  between  the  analy- 
ses of  any  two  samples  or  brands  of  cement  plaster  will  therefore  depend 
on  the  difference  in  composition  between  the  gypsums  from  which  the 
two  samples  were  made. 

56 


COMPOSITION,  PROPERTIES,  AND  TESTS  OF  PLASTERS          57 


TABLE  10. 
ANALYSES  OF  PLASTER  OF  PARIS. 


1. 

2. 

3. 

Silica  (SiO2)  
Alumina  (A12O3)  
Iron  oxide  (Fe2O3)  

u.OO 
0.00 
0.00 

i    0.57 

0.61 

Lime  carbonate  (CaCO3).  . 

0.00 

Lime  sulphate  (CaSO4)  .  .  . 

93.8 

94.53 

96.44 

Water  (H2O) 

6  2 

4  12 

3  51 

1.  Theoretical  composition  of  pure  plaster  of  Paris. 

2,  3.  Stucco,  made  by  Ruby  Stucco  Plaster  Co.,  Ferguson,  Oklahoma. 
2d  Rep.   Okla.   Dep.  Geology,  p.  128. 

TABLE  11. 
ANALYSES  OF  CEMENT  PLASTERS. 


Silica 
(Si02). 

Alumina 
(A12O3)  and 
Iron  Oxide 
(Fe203). 

Lime 
Carbonate 
(CaCO3). 

Magnesium 
Carbonate 
(MgC03). 

Lime 
Sulphate 
(CaS04). 

Water 
(H20). 

1 

39.55 

0.61 

5.79 

0.54 

46.99 

6.42 

2 

1.00 

0.33 

1.50 

0.75 

88.50 

8.00 

3 

1.20 

0.20 

1.68 

1.18 

89.42 

6.86 

4 

4.27 

0.47 

3.07 

1.47 

83.55 

6.67 

5 

12.04 

1.50 

8.44 

2.24 

71.74 

4.80 

6 

0.97 

0.30 

0.04 

1.28 

89.98 

7.29 

7 

0.85 

0.16 

0.94 

1.28 

91.07 

6.33 

8 

11.97 

0.67 

8.11 

0.73 

71.43 

6.98 

9 

14.67 

1.05 

10.07 

0.95 

66.91 

6.41 

10 

5.52 

0.40 

12.00 

1.74 

74.43 

6.99 

11 

9.73 

0.62 

11.30 

0.65 

72.42 

5.49 

12 

19.43 

0.53 

9.59 

64.42 

6.21 

13 

13.29 

0.71 

4.77 

1.91 

73.67 

5.78 

14 

23.38 

2.42 

n.  d. 

n.  d. 

69.41 

5.66 

15 

7.43 

0.12 

5.07 

tr. 

78.66 

8.49 

1.  Florence,  Colorado. 

2.  Rhoades,  Kansas. 

3.  Blue  Rapids,  Kansas,  "  Crystal  Rock  " 

brand,  Great  Western  Plaster  Co. 

4.  Springdale,  Kansas,  "Roman"  brand. 

5.  "Acme" 

6.  Blue      Rapids,     Kansas,     "Sunshine" 

finishing     plaster,      Great      Western 
Plaster  Co. 


7.  Blue  Rapids,  Kansas,  "Ivory"  finishing 

plaster,   Blue  Valley  Plaster  Co. 
8-12.  Blue     Rapids,     Kansas,     "Acme" 

cement  plasters. 
13.  Okarche,  Oklahoma. 
14. 
15.  Quanak,  Texas. 


Weight  and  Fineness  of  Plasters. 

Weight'  and  specific  gravity.  —  Pure  gypsum,  before  calcination 
has  a  specific  gravity  of  2.30  to  2.33,  corresponding  to  a  weight  of  about 
143J  Ibs.  per  cubic  foot,  while  the  specific  gravity  of  plaster  of  Paris  is  about 
2.57.  The  apparent  specific  gravity  of  cement  plaster  in  bulk  is  1.81.* 
This  would  correspond  to  a  weight  of  about  113  Ibs.  per  cubic  foot  if, 
no  allowance  were  made  for  air-spaces.  According  to  the  results  f  of 

*  Wilder,  F.  A.     Vol.  12,  Iowa  Geological  Survey,  p.  139. 
t  Tenth  Ann.  Rep.  Wyoming  Agric.  and  Mech.  College. 


58 


CEMENTS,  LIMES,  AND  PLASTERS. 


Slosson  and  Moudy  on  Laramie  plaster,  a  bushel  weighed  64  Ibs.,  and 
a  block  composed  of  50  parts  sand  and  100  parts  plaster,  after  being  set 
and  dried,  gave  a  specific  gravity  of  1.5,  corresponding  to  a  weight  of 
93^  Ibs.  per  cubic  foot. 

Fineness  of  calcined  plasters. — A  number  of  cement  plasters,  wall- 
plasters,  and  allied  products  from  Iowa,  Kansas,  Texas,  and  Oklahoma 
were  tested  for  fineness  by  Prof.  Marsjpn  in  1900.  The  results*  of  these 
tests  are  given  in  the  following  table.  The  tests  were  made  on  mate- 
rial purchased  in  the  open  market. 

TABLE  12. 

FINENESS  OF  CALCINED  PLASTERS. 
Per  cent  passing  sieve. 


Meshes  per  linear  inch               .                

74 

100 

200 

Average  diameter  of  largest  particle  passing  

0090  1" 

00452" 

0027  1" 

Gypsum,  ready  for  burning,  Stucco  Mills,  Ft.  Dodge, 
Iowa                                   .        .            

68  3 

60  0 

44  0 

Stucco,  Ft.  Dodge  Plaster  Co.,  Ft.  Dodge,  Iowa  
Baker  stucco   Kansas 

71.9 
72  9 

66.2 
58  3 

49.3 
39  5 

Kallolite    stucco,    Cardiff    Gypsum    Plaster    Co.,    Ft. 
Dodge   Iowa 

69  1 

63  8 

50  2 

Baker  plaster  Kansas                                     .    ... 

68  2 

58  7 

28  2 

Mineral  City  wall  -plaster  Ft   Dodge,  Iowa 

72  1 

65  4 

49  1 

Oklahoma  Cement  Plaster  Co.,  Okarche,  Oklahoma.  .  . 
Flint  wall-plaster,  Iowa  Plaster  Association,  Ft.  Dodge, 
Iowa           

77.8 
72  4 

70.2 
64  2 

51.3 
48  1 

Acme  wall-plaster  Acme  Texas 

74  6 

69  2 

56  6 

Kallolite  wall-plaster,  Cardiff  Gypsum  Plaster  Co.,  Ft. 
Dodge   Iowa                               .  .                

70  8 

65  5 

53  5 

Stonewall-plaster,   Ft.  Dodge  Plaster  Co.,  Ft.  Dodge, 
Iowa                           .        

72.4 

66  1 

54  0 

Duncomb     wall-plaster,    Duncomb     Stucco    Co.,    Ft. 
Dodge,  Iowa  

63.8 

57.8 

43  6 

Tensile  and  Compressive  Strength. 

Methods  of  testing  plasters  and  similar  products  have  never  been 
standardized,  and  the  result  is  that  each  investigator  applies  such 
tests  as  he  may  deem  advisable.  In  general  the  practice  has  followed 
closely  along  the  lines  of  cement-testing. 

Tensile  strength  of  plasters. — In  making  the  experiments  discussed 
below,  Professor  Marston  "  mixed  the  plaster  or  stucco  thoroughly, 
by  hand,  with  water.  The  mortar  was  then  placed  in  standard  (Am. 
Soc.  C.  E.)  cement  briquette  molds  and  packed  with  the  finger.  The 
surface  of  the  briquette  was  smoothed  with  a  trowel.  As  soon  as  the 


Iowa  Geological  Survey,  vol.  12,  p.  162- 


COMPOSITION,  PROPERTIES,  AND  TESTS  OF  PLASTERS. 


59 


briquettes  were  sufficiently  set,  which  usually  took  about  three  hours, 
the  molds  were  removed".  Some  of  the  briquettes  were  kept  in  air 
and  some  in  water  for  various  lengths  of  time,  and  they  were  finally 
broken  in  a  Fairbanks  cement-testing  machine.  Preliminary  tests, 
using  various  percentages  of  water,  showed  that  30  to  35  per  cent  of 
water  gave  the  maximum  strength  of  briquettes.  As  35  per  cent  gave 
a  mixture  that  was  more  readily  handled  in  the  making  of  briquettes 
than  the  30  per  cent  mixture,  it  was  adopted  for  the  final  series  of  tests 
whose  results  follow. 

A  series  of  220-day  tests  were  made,  but  the  results  are  of  little  value, 
because  the  briquettes  were  allowed  to  stand  in  very  moist  air  between 
the  28-  and  220-day  periods,  and  therefore  all  showed  a  marked  falling 
off  in  strength.  For  this  reason  the  results  of  the  220-day  tests  are 
omitted  here. 

TABLE  13. 
FINENESS  OF  PLASTERS  TESTED. 


• 

Per  Cent  Passing  Sieve. 

74-mesh. 

100-mesh. 

200-mesh. 

Crystal  Rock  plaster 

73.7 
74.3 
66.4 
81.9 
90.5 

12.3 
55.2 
58.6 
68.7 
85.0 

2.5 
4.3 
55.7 
52.2 
19.8 

a          u          t  ( 

Flint  plaster  fresh       

1  '          '  '        old        

German  stucco     

TABLE  14. 
TESTS  OF  TENSILE  STRENGTH  AND  EFFECT  OF  SAND. 


Neat. 

1  Plaster,  1  Sand. 

1  Plaster,  2  Sand. 

1  Plaster,  3  Sand. 

£ 

Q 

1 
£ 
ft 

4  Weeks. 

3  Months. 

£ 

ft 

T-i 

1  Week. 

4  Weeks. 

3  Months. 

£ 

ft 

55 
57 
64 
61 

26 

49 
119 

1  Week. 

4  Weeks 

3  Months. 

1 

iH 

i 

;£.- 

•  l-< 

148 
132 

303 

4  Weeks. 

3  Months. 

Crystal   Rock   plas- 
ter, unsifted  
Crystal   Rock   plas- 
ter, sifted     

228 

393 

445 

426 

87 

320 

368 

370 

203 
231 
206 
233 
109 

205 
336 

212 
229 
203 
242 
123 

256 
356 

255 
229 

35 
39 

75 

145 
139 

252 

156 

Flint  plaster,  fresh, 
unsifted 

135 

310 

402 

... 

104 

303 

362 

... 

Flint  plaster,  fresh, 
sifted 

Flint    plaster,    old, 
unsifted  
Flint    plaster,    old, 
sifted        

155 

353 

433 

German  stucco 

300 

461 

461 

60 


CEMENTS,  LIMES,  AND   PLASTERS. 


The  results  of  a  later  series  of  tests  carried  *  out  by  Prof.  Marston 
are  given  below.  Most  of  the  tests  were  made  on  fresh  plaster  as  mar- 
keted. A  few,  however,  noted  in  the  table  as  "  sifted",  were  made  on 
that  portion  of  the  plaster  which  passes  through  a  100-mesh  sieve. 
Plaster  four  years  old  was  also  tested,  as  noted  in  the  table.  All  the 
figures  given  are  the  averages  of  from  3  to  15  separate  tests. 


500  Ibs.    —  - 


400  Its. 


300  Ibs. 


200  Ibs. 


100  Ibs.  ( 


rf* 

:\eat  Plasi 

er 

f 

^.^ 

I 

plaster  :  1  si 

nd. 

I1 

paster  ^ 

d.         . 

_-  

i 

>-  -« 

r 

)]aster_:_3_sai 

_d_.  

•< 

V 

FIG.  18. — Effect  of  sand  on  tensile  strength  of  plasters.     (Marston.) 

These  tests  appear  to  show  f  that 

(a)  Cement  plasters  and  stuccos  attain  almost  their  full  strength 
at  the  end  of  one  week,  showing  little  further  gain  at  three  months. 

(6)  The  portion  of  the  plaster  which  passes  a  100-mesh  sieve  is 
stronger  than  the  coarser  portions,  and  the  higher  strength  of  fine  plaster 
is  shown  better  in  sand  mixtures  than  when  tested  neat. 

(c)  The  value  of  fine  grinding  is  further  emphasized  by  the  high 
results  shown  by  the  German  stucco,  which  seems  to  have  been  the 
most  finely  ground  of  all,  though  the  values  of  fineness  given  are  not 
quite  consistent. 

*  Iowa  Geol.  Survey,  vol.  12,  pp.  232-235. 

f  The  conclusions  here  drawn  from  these  tests  are  those  of  the  writer.  For 
Professor  Marston's  conclusions,  which  do  not  entirely  agree  with  mine,  reference 
should  be  made  to  the  original  work. 


COMPOSITION,  PROPERTIES,  AND   TESTS  OF  PLASTERS.         61 


TABLE  15. 
RESULTS  OF  TENSILE  TESTS  OF  PLASTERS,  ETC. 


Material. 

Tensile  Strength  per  Square  Inch. 

Kept  in 

IDay. 

7  Days. 

28  Days. 

Stucco,  Fort  Dodge,  Iowa.  • 

Air 

i  ( 

Water 

Air 

i  ( 

Water  '• 

i  ( 

Air 

t  ( 

Water 

1  1 

Air 

1  1 

Water 

1  1 

i  ( 

Air 

t  ( 

Water 

i  ( 

Air 

i  ( 

Water 

i  ( 

Air 

<  i 

Water 
Air 

Water 

i  ( 

Air 

1  1 

Water 

226 
219 
195 
208 
219 
186 
175 
189 
211 
208 
192 
202 

215 

192 
195 
131 
144 
187 
214 
192 
204 
188 
214 
107 
131 
82 
111 
227 
221 
216 
226 
181 
134 
183 
185 

204 
210 
139 
154 
188 
230 
185 
170 
184 
220 
172 
175 
190 
301 
203 
196 

170 
228 
163 
193 
224 
217 
207 
205 
128 
175 
20 
112 
236 
208 
223 
201 
195 
218 
196 
162 

329 
438 
187 
200 
379 
245 
168 
209 
375 
360 
180 
186 
237 
437 
195 
205 

483 
470 
182 
148 
'348 
285 
158 
163 
333 
303 
151 
154 
468 
461 
154 
181 
465 
286 
195 
215 

Kallolite  plaster  Ft  Dodge,  Iowa 

Duncomb  plaster,  Ft.  Dodge,  Iowa.  .  .  .  .  „  

Mineral  City  plaster  Ft  Dodge,  Iowa 

Stone  plaster,  Ft   Dodge,  Iowa.  .  „  .  »  

Flint  plaster,  Ft.  Dodge,  Iowa;  

Acme  plaster  Acme,  Texas                

Stucco,  Baker  Stucco  Co  ,  Kansas  ,  ,  ........  I 

Plaster,  Baker  Stucco  Co.,  Kansas  

Compression  tests  and  effects  of  sand. — A  valuable  series  *  of  ex- 
periments were  carried  out  during  1899-1900  by  Profs.  Slosson  and 
Moudy  on  the  compressive  strength  of  plasters,  both  neat  and  mixed, 
with  varying  properties  of  sand.  Most  of  the  material  used  for  these 
tests  was  a  cement  plaster  manufactured  at  Laramie,  Wyo.,  the  tests 
being  made  before  .the  addition  of  retarder  to  the  plaster. 

The  material  was  molded  into  2-inch  cubes  and  crushed  in  a  Riehle 
self-registering  machine  after  the  cubes  had  been  exposed  to  the  air 

*  Tenth  Ann.  Rep.  Wyoming  Agric.  and  Mech.  College,  1900. 


62 


CEMENTS,  LIMES,  AND  PLASTERS. 


for  one  week.  "The  sand  used  was  obtained  from  the  Laramie  River 
and  was  composed  of  sharp-angled  granitic  fragments.  It  was  sifted 
through  a  millimeter  sieve." 


2tOO 


JWOO 


1800 


1600 


1100 


1200 


1000 


600  Ibs. 


1|         11         11         111 
FIG.  18a. —  Effect  of  sand  on  compressive  strength  of  plaster. 

Adhesive  tests  of  plasters. — The  adhesive  tests  in  Table  17  were 
made  by  Prof.  Marston  "by  taking  pieces  of  No.  2  paving-brick  from 
Des  Moines  and  grinding  them  on  the  emery-wheel  so  as  to  make 
approximately  1-inch  cubes.  Each  cube  had  one  face  carefully 


COMPOSITION,  PROPERTIES,  AND   TESTS  OF  PLASTERS.         63 


trued  to  give  a  cross-section  exactly  1  inch  square.  These  pieces 
of  paving-brick  were  placed  in  the  cement  briquette  molds  with  this 
true  surface  exactly  at  the  middle  of  the  mold.  The  plaster  or  stucco 
was  placed  to  fill  the  other  half  of  the  mold,  while  the  half  in  which 
the  piece  of  brick  was  placed  was  filled  with  neat  Portland-cement 
mortar  ". 

TABLE  16. 
EFFECT  OF  SAND   ON  COMPRESSIVE  STRENGTH  OF  PLASTERS. 


Parts  by  Weight. 

Number 

Strength, 

Lbs. 

Kind  of  Plaster. 

of 

2-inch 

per 

Tests. 

Cube. 

Sq.  In. 

Plaster. 

Sand. 

Water. 

Laramie  plaster,  no  retarder.  .  . 

100 

0 

56 

4 

5435 

'1358f 

100 

12$ 

56 

2 

5430 

1357i 

100 

25 

57 

10 

4575 

1143f 

. 

100 

50 

58ft 

5 

4378 

1094^ 

' 

100 

75 

eo 

7 

4317 

1079i 

100 

100 

611 

6 

3755 

938| 

100 

125 

62  1 

7 

3505 

876i 

100 

150 

63A 

8 

3341 

835} 

100 

1V5 

•    65 

6 

3523 

880i 

Red  Buttes  plaster,  no  retarder 

100 

0 

50 

? 

8945 

22361 

u             a                 tt             it             ti 

100 

100 

55 

? 

6622 

1655^ 

Agatite  plaster,  market  sample 

100 

0 

50 

? 

3550 

8873 

100 

100 

55 

? 

2597 

649| 

TABLE  17. 
ADHESIVE  STRENGTH  OF  PLASTERS. 


Material. 

•  Adhesive  Strength  per  Square 

Kept  in 

7  Days. 

28  Days. 

133 
75 
115 

102 

81 
84 
212 
84 
80 
114 

103 
117 
100 
105 
95 

133 

Stucco   Ft   Dodge   Iowa 

Air 
Water 
Air 
Water 
Air 
Water 
Air 
Water 
Air 
Water 

Air 

« 

Water 

Air 

t  i 

Water 
Air 
Water 
Air 
Water 

87 
87 
45 
31 
52 
43 
62 

72 

31 

64 
26 
76 

98 
83 
55 
82 
63 

t  i         t  t        t  t           it 

Kallolite  stucco,  Ft   Dodge,  Iowa           

tt            it                  a          it 

"       plaster,             "          "    . 

tt                         (1                                    11                     ti 

Duncomb     "                  "          "... 

K             K                 a          n 

Mineral  City  plaster  Ft   Dodge   Iowa 

n          tt          t  t        t  t         n          t  i 

Stone  plaster  Ft   Dodge   Iowa                     

Flint        "         '  l        "          "                

it               tt             (  e           (  t              i  ( 

Acme  plaster  Acme,  Texas      

Baker  stucco,  Kansas    

t  t          t  i             it 

1  '      plaster,      "                   « 

ii           t  t            it 

Plaster  Okarche   Oklahoma              

1  1                    e  (                        it 

64  CEMENTS,  LIMES,  AND  PLASTERS. 

Rate  of  Set  and  Hardening. 

A  pure  plaster  of  Paris  will  normally  harden  or  set  in  from  five  to 
fifteen  minutes  after  having  been  mixed  with  water.  Plasters  made 
from  impure  gypsum  will  be  considerably  slower  setting  than  this, 
setting  usually  in  from  one  to  two  hours. 

When  plasters  are  to  be  used  for  structural  work,  they  must  be 
either  naturally  slow-setting,  like  somtf  of  the  cement  plasters,  or  be 
made  slow-setting  by  proper  treatment.  Retarders  are  therefore  used 
at  plaster-plants  in  preparing  their  product  for  the  market.  Occasion- 
ally, though  rarely,  a  plaster  will  be  naturally  too  slow  setting  for  the 
particular  use  to  which  it  is  to  be  applied.  In  this  case  an  accelerator 
must  be  used. 

Theory  of  the  action  of  retarders  and  accelerators. — As  will  be  noted 
later,  the  materials  most  commonly  used  as  retarders  are  glue,  tankage, 
and  other  organic  and  uncrystallized  materials,  while  accelerators  are 
usually  inorganic  and  crystallized.  This  fact  suggested  a  theory  as 
to  the  cause  of  the  action  of  accelerators  and  retarders.  The  theory, 
as  set  forth  *  by  its  originator,  Dr.  Grimsley ,  is  as  follows : 

Dr.  Grimsley  assumes  that  the  set  of  plaster  is  due  to  the  presence 
of  a  few  small  crystals  which  have  escaped  dehydration  during  burning 
and  which  set  the  example,  so  to  speak,  to  the  other  crystals  to  form; 
and,  further,  that  the  strength  of  the  set  material  is  due  to  the  formation 
of  a  mass  of  interlacing  crystals.  The  action  of  retarders  and  accelerators 
is  therefore  explained  by  assuming  that  "any  substance  [added  to  the 
water  with  which  the  calcined  plaster  is  mixed,  or  to  the  dry  plaster] 
which  will  keep  the  molecules  apart  or  from  too  close  contact  will 
retard  the  setting.  Such  substances  are  dirt  or  organic  matter  that 
is  not  of  a  crystalline  character ".  On  the  other  hand,  the  action  of 
accelerators  is  ascribed  to  the  fact  that,  being  of  crystalline  character, 
they  induce  crystallization  in  the  plaster  to  which  they  are  added. 

It  is  probable  that  the  researches  of  Rohland  on  the  effect  of  various 
substances  on  the  speed  of  hydration  of  plasters,  Portland  cement,  etc., 
are  directly  applicable  to  the  question  on  hand.  In  summing  up  his 
conclusions,  Rohland  decided  that  substances  which  increase  the  solu- 
bility of  the  cementing  material  accelerate  its  speed  of  hydration,  while 
substances  which  decrease  the  solubility  of  the  cementing  material 
retard  its  hydration. 

Materials  used  as  retarders. — The  materials  used  as  retarders  are 
usually  of  animal  or  vegetable  origin.  Glue,  sawdust,  blood,  and  packing- 

*  Vol.  5,  Reports  Geological  Survey  Kansas,  pp.  167,  168. 


COMPOSITION,  PROPERTIES,  AND  TESTS  OF  PLASTERS.         65 


house  tankage  are  some  of  the  retarders  most  commonly  used.  Many 
"patent"  retarders  are  also  on  the  market,  most  of  which  are  based 
on  one  or  more  of  the  organic  materials  noted  above. 

In  the  course  of  the  experiments  by  Slosson  and  Moudy,  recorded 
below,  an  effort  was  made  to  obtain  a  cheap  and  satisfactory  home- 
grown retarder.  With  this  in  view  a  common  western  cactus  (Opuntia 
platycarpia)  was  dried  and  ground.  The  common  malva  (Malvastrum 
coccineum)  was  also  prepared  in  a  similar  manner.  The  retarders  thus 
made  were  light  green  in  color,  possessed  no  disagreeable  odor,  and  when 
used  in  the  proportion  of  2  pounds  of  retarder  to  a  ton  of  plaster  gave 
excellent  results.  It  is  probable  that  many  other  plants,  dried  and 
ground  in  similar  fashion,  would  form  satisfactory  retarders. 

Effect  of  retarders  on  strength  of  plasters. — The  following  table  * 
contains  the  results  of  compression  tests  by  Profs.  Slosson  and  Moudy 
on  plasters  containing  various  amounts  of  retarder.  It  appears  to 
show  conclusively  that  the  compressive  strength  (and  inferentially  the 
tensile  strength)  of  plasters  decreases  as  the  amount  of  retarder  in- 
creases. 

TABLE  18. 
EFFECT  OF  RETARDERS  ON  STRENGTH  OF  PLASTERS. 


Pounds  of 

Crushing  Strength  in  Pounds. 

Retarder  per 

Ton  of 

Plaster. 

2-inch  Cube. 

Per  Square 
Inch. 

Laramie  plaster  

0 

5435 

1358.75 

2 

4065 

1016.25 

Red  Buttes  plaster.  .  . 

0 

8945 

2236.25 

it         (i           (i 

2 

7192 

1798.00 

{  (         it           11 

4 

6480 

1620.00 

In  making  the  tests  the  finely  ground  retarder  was  accurately 
weighed  and  thoroughly  mixed  with  the  dry  plaster.  Water  was  then 
added  and  the  mixture,  placed  on  a  glass  plate,  was  fashioned  into  a 
pat  about  4  inches  in  diameter.  For  determining  the  setting  time 
two  needles  were  used,  each  -rV  inch  in  diameter,  one  loaded  with  'a  weight 
of  \  lb.,  the  other  with  a  weight  of  4  Ibs.  The  time  when  the  more 
lightly  weighted  needle  ceased  to  make  a  decided  impression  on  the 
surface  of  the  plaster  pat  is  reported  as  "  initial  set ",  and  when  the 
more  heavily  weighted  needle  was  supported  without  indenting  the 
plaster  is1  reported  as  "  final  set ". 

*  Tenth  Ann.  Rep.  Wyoming  Agric.  and  Mech.  College. 


66 


CEMENTS,  LIMES,  AND  PLASTERS. 


TABLE  19. 
EFFECT  OF  VARIOUS  RETARDERS  ON  RATE  OF  SET. 


Kind  of  Plaster. 

Kind  of  Retarder. 

Pounds 
Retard- 
er per 
Ton. 

Initial 
Set, 
Minutes 

Final 
Set, 
Minutes 

Remarks. 

Laramie         

None     .  .  .  .  ".  .  i  .  .  . 

(U 
?' 
? 
1 
2 
4 
6 
8 
2 
4 
6 
8 
1 
2 
4 
6 
1 
2 
2 
4 
4 
6 
6 
2 
2 
4 
6 
2 
4 
6 
6 
6 
10 
0 
0 
0 
2 
8 
0 
2 
8 
? 
? 

145 
280 

320 
365 
520 
590 
785 
350 
535 
735 
755 
260 
265 
280 
290 

215 
255 
250 
255 
250 
215 
245 
275 
250 
290 
245 
280 
275 
290 
240 
260 
30 
24 
20 
60 
270 
50 
285 
505 
310 
240 

225 
335 
720 
380 
430 
655  « 
690 

390 
645 

sio 

310 
315 
320 
310 
250 
315 
315 
310 
300 
255 
285 
320 
310 
340 
295 
295 
310 
375 
320 
330 
50 
42 
32 
105 

'so 

345 

375 
305 

Cracked  a  little. 
Never  hardened. 

Cracked  somewhat. 
Cracked  badly. 
Did  not  set. 

Did  not  set. 
Soft-cracked. 

t 

Market  sample.  .  .  . 

«            <  ( 

Wyrnore  

( 

i 

t 

t 

i 

t 

t 

n 

t 

It 

Webster  Citv 

tl 

<            it" 

tt 

(            et 

It 

t            ({ 

tt 

Swift's,  Chicago.  . 
«            <( 

(i            1  1 
ft            1  1 

Swift's,  Kansas  City 

n            ((           t 

(I                      (  C                    ( 

1  1                  11                ( 
'.  t                  11                ( 
(I              11             I 
(  t                  {  {                ( 

Cactus 

tt 

tt 

tt 

tt 

tt 

tt 

tt 
tt 

tt 

tt 

tt 

tt 

i  i 

tt 

i  ( 

tt 

(t 

tt 

Malva    

tt 

« 

tt 

e  t 

tt 

Glucose 

tt 

Clay  (bentonite).  . 

.   t(             t  i 

None  

tt 

Red  Buttes  stucco 
1  1 

ft 
it 

ti 

Red  Buttes  plaster. 

(i  • 

1  1 
1  1 

Agatite  plaster.  .  .  . 

i  ( 

1  1 

Wymore 

(i 

None      

Wymore  

Market  sample.  .  .  . 

Use  of  accelerators. — In  making  dental  plaster  and  plaster  for 
certain  other  purposes  an  extremely  rapid  set  is  desirable.  For  this 
purpose  many  crystalline  salts  are  available,  common  salt  being  one  of 
the  best  accelerators  known. 


COMPOSITION,  PROPERTIES,  AND   TESTS  OF  PLASTERS.         67 


TABLE  20. 
EFFECT  OF  ACCELERATORS  ON  RATE  OF  SET. 


Kind  of  Plaster. 

Kind  of  Accelerator. 

Pounds 
Accelerator 

Time  of  Set 

in  Minutes. 

per  Ton. 

Initial  Set. 

Final  Set. 

Laramie  

None  

o 

145 

225 

1  1 

Common  salt  

6 

55 

150 

i  ( 

Sodium  sulphate.  .  .  . 

6 

150 

170 

1  1 

Sodium  carbonate 

6 

145 

170 

References  on  properties  and  tests  of  plasters. — The  following  brief 
list  covers  the  principal  papers  on  this  subject. 

Bailey,  E.  H.  S.  On  the  chemistry  of  gypsum,  plaster  of  Paris,  and  cement 
plaster.  Vol.  5,  Reports  Kansas  Geological  Survey,  pp.  134-170. 

Marston,  A.  Preliminary  tests  of  stucco  and  plaster  made  by  the  Civil  En- 
gineering Department  of  Iowa  State  College.  Vol.  12,  Reports  Iowa 
Geological  Survey,  pp.  224-235.  1902. 

Slosson,  E.  E.,  and  Moudy,  R.  B.  The  Laramie  cement  plaster.  10th  Ann. 
Rep.  Wyoming,  College  Agriculture  and  Mechanics,  1900. 

Anon.     Tests  for  plaster  of  Paris.     Stone,  vol.  25,  pp.  331-334.     1903. 

Hardening  gypsum  and  plaster. — The  following  methods  of  harden- 
ing an  ordinary  plaster  have  been  recently  recommended :  * 

(1)  Two  to  four    per  cent  of  finely  ground  marshmallow-root  are 
intimately  mixed  with    powdered   plaster    and   the   mixture   kneaded 
to  a  dough  with  40  per  cent  of  water.     The  resulting  mass  resembles 
a  stiff  clay,  hardens  in  about  an  hour,  and  finally  becomes  hard  enough 
to  cut,  file,  or  bore.     A  harder  and  tougher  mass  may  be  obtained  by 
increasing  the   quantity   of  marshmallow-root   to   8  per   cent.      Gum, 
dextrin,  or  glue  may  be  substituted  for  the  marshmallow-root  if  more 
convenient.      If  the  objects  are  to  be  exposed  to  high  temperatures 
shellac  may  be  used. 

(2)  Six  parts  of  gypsum  are  mixed  with  one  part  of  freshly  slaked 
lime  and  the  mixture  is  soaked  with  a  concentrated   solution  of  mag- 
nesium sulphate.     In  preparing  this  mixture,  too  much  gypsum  must 
not  be  poured  into  the  water,  and  the  mixture  must  be  stirred  quickly 
so  that  lumps  do  not  form.     The  smaller  the  quantity  of  water  used 
the  thicker  and  firmer  is  the   cement.     The  porosity  caused  by  the 
gradual  loss  of  water  can  be  obviated  by  soaking  the  objects  in  a  solu- 
tion of  ozocerite  or  wax  in  oil  of  turpentine,  varnish,  or  hot  tar,  or  by 
coating  them  with  shellac. 

*  Journ.  Soc.  Chem.  Industry,  vol.  21,  p.  347. 


CHAPTER  IV. 
FLOORING-PLASTER^  AND   H&RD-FINISH   PLASTERS 

THE  two  groups  of  plasters  to  be  considered  in  this  chapter  agree 
(1)  in  being  prepared  by  burning  gypsum  at  a  hjgher  temperature 
than  is  employed  in  the  manufacture  of  plaster  of  Paris  and  "  cement  " 
plasters,  and  (2)  in  being  products  which;  for  plasters,  set  rather  slowly 
but  finally  take  on  great  hardness.  Because  of  these  last  properties, 
the  flooring-plasters  and  hard-finish  plasters  are  available  for  certain 
uses  to  which  ordinary  plasters  are  ill  adapted.  So  much  for  the  resem- 
blances between  the  two  groups.  Their  points  of  difference  are,  that 
the  flooring-plasters  are  prepared  by  simple  burning  at  high  tempera- 
tures, while  the  hard-finish  plasters  are  produced  by  a  double  burning, 
with  the  additional  use  of  chemicals. 

Neither  product  is  made  to  any  extent  in  the  United  States,  though 
a  considerable  quantity  of  hard-finish  plasters  are  imported  every  year. 
The  data  obtainable  as  to  processes  of  manufacture  are  scanty,  and 
the  descriptions  published  are  often  contradictory,  so  that  it  has  been 
difficult  to  prepare  a  satisfactory  account  of  these  products.  It  is 
believed,  however,  that  the  descriptions  given  below  contain  no  errors 
of  importance. 

Flooring-plasters. 

The  flooring-plasters  ("  Estrichgips "  of  German  reports)  include 
those  plasters  made  by  calcination  of  a  relatively  pure  gypsum  at  tem- 
peratures of  400°  F.  or  higher. 

In  the  literature  of  gypsum  and  plaster  it  is  often  stated  that  gypsum, 
burned  at  temperatures  exceeding  400°  F.,  yields  a  completely  dehy- 
drated product— an  artificial  anhydrite — which  is  entirely  valueless  as 
a  structural  material,  because  it  has  completely  lost  its  property  of  re- 
combining  with  water.  This  statement  is,  however,  erroneous,  for  plas- 
ters burned  at  such  temperatures  are  regularly  made  and  used.  They 
set  with  extreme  slowness,  however,  and  require  very  fine  grinding. 

Composition  of  flooring-gypsum. — Until  very  recently  no  satisfac- 
tory discussion  of  this  phenomenon  had  been  attempted,  and  the  few 
published  accounts  of  the  manufacturing  processes  employed  were  con- 

68 


FLOORING-PLASTERS  AND  HARD-FINISH   PLASTERS.  69 

tradictory  as  to  temperatures  reached,  composition  of  product,  etc. 
Fortunately,  however,  a  detailed  account  *  of  the  chemical  changes 
involved  was  published  during  1903  by  Van't  Hoff  in  the  Transactions 
of  the  Berlin  Academy  of  Sciences.  As  this  paper  is  practically  inac- 
cessible to  the  American  engineer  or  manufacturer,  a  translation  f  is 
here  appended: 

"As  a  complement  to  the  investigations  on  gypsum  and  anhydrite 
we  have  turned  our  attention  to  a  kindred  product,  usually  designated 
by  the  term  hydraulic  gypsum  or  floor-gypsum  (Estrichgips).  It  is 
obtained  by  burning  natural  gypsum,  CaS04.2H2O.  When  natural 
gypsum  is  worked  up  into  stucco  gypsum  (CaSO^.H^O,  in  the  process 
called  cooking,  the  temperature  of  120°-130°  C.  is  not  exceeded;  but 
in  the  preparation  of  floor-gypsum  higher  temperatures  are  applied. 
Accordingly  the  product  is  free  from  water,  but  we  are  not  in  this  case 
dealing  with  dead-burned  gypsum,  since  the  capacity  to  bind  water  has 
not  yet  been  lost.  However,  the  time  required  for  setting  is  much  longer 
than  in  the  case  of  stucco  gypsum ;  the  latter,  as  every  one  knows,  hardens 
in  about  a  quarter  of  an  hour,  while  the  hardening  of  the  floor-gypsum 
takes  place  only  after  some  days,  and  the  complete  absorption  of  the 
amount  of  water  theoretically  required  may  take  weeks. 

"  Composition  and  structure  of  floor-gypsum. — Some  indications 
in  literature  suggested  that  in  this  floor-gypsum  we  are  dealing  with 
a  basic  sulphate.  Accordingly  a  commercial  floor-gypsum  was  first 
analyzed;  it  showed  38.6%  CaO,  54.3%  SOs,  and  foreign  ingredients. 

"  From  this  the  ratio  of  CaOiSOs  in  molecules  is  found  to  be  1.01:1. 
The  product  therefore  is  calcium  sulphate  anhydrite  without  any  notable 
surplus  of  lime.  The  fact  that  but  slight  quantities  of  lime  are  present 
was  also  demonstrated  in  another  way:  1.134  gr.  of  the  substance  was 
boiled  for  3^  hours  with  75  ccm.  of  0.425  normal  potassium  hydroxide, 
whereupon  everything  went  into  solution  except  slight  impurities. 
To  titrate  back,  47.8  ccm.  of  potassium  hydroxide  were  then  required, 
which  indicates  a  content  in  free  lime  corresponding  to  125— (75  +  47.8) 
=  2.2  ccm.  in  weight  0.026  gr.  or  about  2  per  cent  of  the  whole. 

"  Having  ascertained  this  composition,  it  only  remained  to  answer 
the  question  as  to  the  relation  which  the  floor-gypsum  bears  to  the 
two  known  modifications  of  anhydrous  calcium  sulphate,  namely,  the 
natural  and  the  soluble  anhydrite.  The  difference  between  these  two 
lies  in  this,  that  the  former  is  practically  incapable  of  binding  water, 
that  is  to  say,  it  does  so  with  extreme  slowness,  and  thus  acts  like  dead- 
burned  gypsum,  while  the  soluble  anhydrite  takes  up  water  even  more 
rapidly  than  stucco  gypsum  does. 

"A  first  hint  was  obtained  from  the  microscopic  examination.  As 
shown  by  this,  the  floor-gypsum  consists  for  the  most  part  of  distinctly 

*  Van't  Hoff  and  Just,  G.  Der  hydraulicshe  oder  sogennante  Estrichgips. 
Sitzungsberichte  der  Kgl.  Preuss.  Akad.  der  Wissenschaften,  1903,  B.  I,  pp.  249-258. 

f  For  this  translation  the  writer  is  indebted  to  Dr.  Robert  Stein,  formerly  of 
the  U.  S.  Geological  Survey. 


70 


CEMENTS,  LIMES,  AND   PLASTERS. 


recognizable  needles;  these  have  the  form  of  the  crystalline  plaster 
of  Paris  (CaSO^H^O.  As  floor-gypsum  contains  no  water,  the  needles 
are  evidently  pseudomorphs  after  plaster  of  Paris.  >  It  may  be  added 
that  stucco  gypsum,  though  consisting  essentially  of  half  hydrate  is 
far  from  showing  the  crystalline  development  of  the  floor-gypsum. 

"In  view  of  this  striking  crystalline < condition,  we  directed  our  in- 
vestigation not  only  to  the  influence  of  the  burning  temperature  but 
also  to  the  possible  influence  of  this  factor  (crystalline  form). 

"To  get  an  idea  of  the  hardening  property,  observation  is  naturally 
directed  first  to  the  process  as  carried  out  in  practice,  and  we  did  not 
fail  to  follow  it  on  a  small  scale.  However,  we  soon  felt  the  need  for  a 
process  which  would  enable  this  hardening  to  be  traced  with  greater 
accuracy  quantitatively.  For  this  purpose  we  use'd  the  change  of 
volume  in  hardening  and  the  weighing  of  the  quantity  of  water  taken  up. 

"1.  Change  of  volume  on  hardening. — When  the  practicability  of 
the  volume  process  was  first  tested  in  the  case  of  stucco  gypsum,  a 
great  irregularity  manifested  itself,  which  was  not  observed  in  the  case 
of  floor-gypsum.  Hence  we  might  pass  those  preliminary  experiments 
without  mention  did  they  not  furnish  the  explanation  of  the  well-known 
fact  that  the  hardening  of  gypsum,  though  accompanied  by  contraction, 
nevertheless  may  lead  to  the  breaking  of  the  vessels  in  which  it  takes 
place. 

"The  apparatus  consisted  of  a  small  flask  with  narrow  neck;  the 
sample  of  gypsum,  haying  been  weighed,  is  introduced,  and  then  a  closed 
capillary  is  sealed  to  it,  which  at  a  short  distance  above  the  flask  bears 
a  lateral  branch  with  stop-cock.  By  means  6"f  this  the  apparatus  is 
connected  with  the  air-pump,  and,  after  evacuation,  is  placed  in  a  ther- 
mostat filled  with  gypsum-water  at  25°.  The  stop-cock  is  opened  and 
gypsum-water  is  allowed  to  flow  in.  Gpysum-water  is  used  instead 
of  ordinary  water,  in  order  to  avoid  the  change  of  volume  accompanying 
the  solution  of  the  gypsum.  After  closing  the  stop-cock  and  breaking 
off  the  upper  end  of  the  capillary,  the  reading  of  the  level  in  the  latter 
may  be  performed  by  means  of  a  millimeter  scale  one  minute  after  the 
introduction  of  the  gypsum-water. 

"  The  following  table  shows  the  result  of  such  an  observation: 


Time  in 
Minutes. 

Height  in 
Millimeters. 

Time  in 
Minutes. 

Height  in 
Millimeters. 

2 

540 

38 

374 

5 

522 

41 

375 

8 

486 

44 

376 

11 

448 

47 

377 

14 

408 

50 

378 

17 

385 

53 

380 

20 

374 

56 

381 

23 

371 

59 

383 

26 

370 

62 

387 

29 

370 

65 

388 

32 

371 

166 

413 

35 

372 

870 

438 

FLOORING-PLASTERS  AND  HARD-FINISH   PLASTERS. 


71 


"On  the  whole,  therefore,  a  contraction  takes  place,  as  is  required, 
in  fact,  by  the  molecular  volumes  at  25°: 


Molecular 
Weight. 

Specific 
Gravity. 

Molecular 
Volume. 

CaS04£H2O.  . 
CaSO42R~O    

145.17 
172  19 

2.75 
2  32 

52.79 
74  22 

H2O            

18  016 

0  997 

18  07 

Hence  for 


J7=  -5.68. 

However,  after  a  rather  large  contraction  (from  540  to  370)  a  transient 
expansion  (from  370  to  438)  manifests  itself. 

"  Although  this  peculiar  behavior  suggested  the  transient  formation 
of  an  intermediate  product,  yet  all  attempts  to  isolate  such  a  product 
were  in  vain.  The  explanation  is  found  in  another  way:  the  solubility 
of  the  stucco  gypsum  (CaSO^-J^O)  is  much  greater  than  that  of  normal 
gypsum  (according  to  Marignac  one  part  of  CaS04  in  the  first  form  dissolves 
in  110  parts  of  water,  while  of  the  second  form  one  part  dissolves  only 
in  479  parts  of  water  at  24°)  ;  thus  the  solution  first  formed  is  over- 
saturated  with  gypsum  and  precipitates  the  latter.  Now,  as  shown 
by  direct  experiment,  this  process  is  accompanied  by  considerable 
expansion;  in  the  same  apparatus,  when  0.54  gram  of  gypsum  was 
thrown  down  from  the  o  versa  tura  ted  solution,  there  was  a  rise  of 
78  mm.  in  the  scale,  that  is  to  say,  quite  comparable  with  the  above  value 
(conversely  the  solution  of  gypsum  was  accompanied  by  a  contraction). 
Undoubtedly  connected  with  this  process  is  the  sweating-out,  which 
is  occasionally  observed  in  casts  of  stucco  gypsum.  While,  therefore, 
the  volume  method  of  ascertaining  the  process  of  the  hardening  of 
stucco  gypsum  is  to  be  rejected,  a  satisfactory  regularity  appears  in 
the  case  of  floor-gypsum,  as  shown  by  the  following  table  : 


Time. 

Level  in 
mm. 

Time. 

Level  in 
mm. 

1  minute 

405 

8  days  6  hours 

322 

6  minutes 

395 

9   '  22 

314 

11   " 

393 

11      6 

309 

16 

392 

14      0 

301 

45   " 

390 

15      4 

297 

100   " 

388 

15     22 

295 

430   " 

383 

17      6 

292 

1  day  0  hours 

370 

18      7 

290 

1  "   7 

365 

18    23 

288 

3  days  0   ' 

349 

20     0 

285 

4  «  4  < 

342 

21      0 

282 

5  "  0   ' 

33S 

22      8 

'279 

7  ""  0   ' 

327 

53     0 

243 

1 

72 


CEMENTS,  LIMES,  AND   PLASTERS. 


"The  observed  diminution  of  volume  corresponds  to  expectation, 
regard  being  had  to  the  molecular  volumes  at  25°: 


Molecular 
Weight. 

Specific 
Gravity. 

Molecular 
Volume. 

CaSO4 

136.16 

2.97 

45   85 

CaSO42H  O 

172  19 

2  32 

74  22 

H20.  . 

18.016 

0.997 

18.07 

j* 

Hence  for 


CaS04 + 2H20  =  CaS042H20, 


J7=-7.77. 


"The  observed  diminution  of  volume  satisfied  this  requirement  even 
quantitatively,  inasmuch  as  11.63  grams  of  floor-gypsum  caused  an 
expansion  of  0.63  c.c.,  that  is  to  say,  0.054  per  gram,  while  calculation 
.gives  0.057.  It  may  be  added  that  the  water  content  of  the  mass  formed 
(20.6  per  cent)  corresponded  to  the  total  transformation  into  gypsum 
(20.9  per  cent). 

"  With  the  aid  of  this  method  we  traced  the  influence  which  the 
burning  temperature  has  on  the  setting  capacity.  In  particular  we 
investigated  the  contradictory  statements  whether  the  formation  of 
the  gypsum  capable  of  setting  takes  place  at  a  temperature  higher 
than  that  at  which  dead-burning  ensues  or  whether  with  rising  tem- 
perature the  binding  capacity  is  gradually  lost.  This  determination  is 
important,  for  according  to  the  above  statement  a  dead-burned  gypsum, 
and  probably  also  the  natural  anhydrite,  would  acquire  binding  capacity 
by  appropriate  burning.  Let  it  be  stated  at  once  that,  so  far  as  our 
observations  go,  the  binding  capacity  decreases  regularly  with  increas- 
ing burning  temperature. 

"  In  this  respect  we  had  previously  found  that  an  anhydrite  pre- 
pared at  100°  hardens  even  more  quickly  than  stucco  gypsum.  A  real 
burning  can  only  be  spoken  of  above  190°,  for  it  is  only  above  that 
temperature  that  the  water  develops  out  of  half-hydrate  at  a  tech- 
nically utilizable  rate.  Hence  we  first  of  all  heated  samples  of  well- 
crystallized  half-hydrate  (obtained  from  gypsum  with  nitric  acid)  at 
200°  and  300°  for  ten  hours  each.  The  volume  experiment  showed 
in.  the  case  of  the  latter  sample  a  decrease  of  binding  capacity: 

200° ;  2 . 624  gr.     Capillaries :  1  mm.  =  0 . 00382  c.c. 


Time   

1  min. 

6  min. 

26  min. 

85  min. 

172  min. 

23  \  hrs. 

46  hrs. 

00 

Level  in  mm. 

491 

481 

472 

464 

463 

459 

456 

456 

300°;  2  gr.     Capillaries:  1  mm.  =0.00323  c.c. 


Time  

1  min. 

20  min. 

28  min. 

86  min. 

122  min. 

7  hrs. 

21  hrs. 

00 

Level  in  mm.  . 

506 

500 

499 

496 

495 

493 

487 

472 

FLOORING-PLASTERS  AND   HARD-FINISH  PLASTERS. 


73 


"  It  appears  that  the  gypsum  heated  at  300°  sets  more  slowly  than 
that  which  has  been  heated  at  200°;  after  23£  hours,  for  example,  93  per 
cent  were  set  in  the  former  case,  in  the  latter  after  21  hours  only  56 
per  cent. 

"  As  these  results  rendered  it  probable  that  the  floor-gypsum  is  not 
a  product  of  a  temperature  higher  than  the  dead-burning  temperature, 
but  that  dead-burning  ensues  only  after  the  formation  of  floor-gypsum, 
we  heated  a  floor-gypsum  for  10  hours  at  400°.  The  setting  capacity 
had  been  thereby  considerably  decreased: 

Unheated  sample,  2  gr.     Capillaries:  1  mm.  =0.00398. 


Time 

1  min 

8  min 

44  min 

6  hrs 

93  hrs 

6  dys 

1Q  Hv<? 

Level  in  mm.  . 

543 

543 

541 

540 

539 

532 

528 

519 

Heated  sample,  2  gr.     Capillaries:  1  mm.  =0.00323. 


Time 

1  min 

12  min 

17  hrs 

1Q  five 

Level  in  mm  

527 

526 

523 

518 

514 

494 

"Thus  in  the  first  case  67  per  cent  were  set  after  thirteen  days, 
in  the  second  case  only  39  per  cent. 

"  On  inquiring  for  a  sample  of  dead-burned  gypsum  from  the  same 
source,  it  appeared  that  it  was  a  very  finely  crystallized  half-hydrate 
with  the  quantity  of  water  corresponding  to  the  hydrate  (7.3  per  cent 
instead  of  6.2  per  cent). 

"A  brief  ignition  of  the  commercial  floor-gypsum  in  the  platinum 
crucible  finally  led  to  dead-burning,  and  the  sample  did  not  harden 
even  after  weeks. 

"2.  Increase  of  weight  on  hardening.  Exactly  the  same  result, 
that  is  to  say,  a  gradual  decrease  of  the  binding  capacity  with  increas- 
ing burning  temperature,  was  obtained  on  following  the  amount  of 
water  absorbed  in  a  moist  atmosphere.  For  this  purpose  the  samples 
were  placed  on  watch-crystals  under  a  globe  alongside  of  water.  Well- 
crystallized  half-hydrate,  obtained  from  gypsum  with  nitric  acid,  was 
heated  for  ten  hours  at  200°,  300°,  and  400°  respectively,  and  there- 
upon the  absorption  of  water  was  followed  by  means  of  weighing.  The 
result  is  contained  in  the  following  table: 


Time. 

200°  in  Gr. 

4 

300°  in  Gr. 

4 

1 

3 
6 
?9 

0 
hour     0  minutes  
hours  40        "      
10        "      
5        "      . 

0.5 
0  .  5027 
0.5069 
0.5104 
0  5413 

0.0027 
0.0042 
0.0035 
0.0309 

0.5 
0,5015 
0.5039 
0.5060 
0  5240 

0.0015 
0.0024 
0.0021 
0.0180 

?8 

0        "      ... 

0  5504 

0  .  0309 

0  5266 

0.0026 

45 

30        "      

0  5665 

0.0161 

0  5381 

O.OliS 

52 

0        "      

0  5670 

0.0005 

0  5384 

0.0003 

69 
95 
131 

30        "      
30        "      
30        " 

0.5760 
0  .  5868 
0  6016 

0  .  0090 
0.0108 

0.5440 
0  .  5521 
0  5688 

0  .  0056 
0.0081 

74 


CEMENTS,  LIMES,  AND   PLASTERS. 


Time. 

300°  in  Gr. 

4 

400°  in  Gr. 

4. 

0 
1  hour    30  minutes.  .... 
5  hours  30        '  '      

22      '  '      50        " 

0.5 

0.5061 
0  .  5100 
0  5239 

0.0061 
0.0039 
0.0139 

0.5 
0  .  5062 
0  .  5090 
0  5187 

0.0062 
0.0028 
0.0097 

48      "      50        "      
94      "      50        "      

0.5410 
0  .  5584 

0.0171 
0.0174 

0.5238 
0  .  5320 

0.0051 
0.0082 

"By  this  method  the  floor-gypsum,  when  heated  for  ten  hours  at 
400°,  showed  an  unmistakable  loss  of  binding  capacity: 


Time. 

Commercial 
Floor-gypsum. 

4i- 

Commercial 
Floor-gypsum 
Heated  to  400°. 

*» 

0 
1  hour     0  minutes  

0.5 
0  5031 

0  0031 

0.5 
0  5035 

0  0035 

2  hours    0        "      
9      "        0        "      
23      "      40        "      

0  .  5046 
0  .-5093 
0.5130 

0.0015 
0.0047 
0  0037 

0.5046 
0.5082 
0  5107 

0.0011 
0.0036 
0  0025 

72      "      30        "      

0.5170 

0.0040 

0.5134 

0.0027 

"While  the  determination^of  the  influence  of  temperature  was  pos- 
sible both  by  dilatometric  methods  and  by  weighing,  the  determina- 
tion of  the  influence  of  crystalline  structure  was  rendered  impossible 
in  both  cases  by  the  fact  that  we  had  to  deal  with  an  uneven  surface. 
Nevertheless  the  orienting  experiments  showed  that  the  half-hydrate 
crystalline  form,  if  retained,  exerts  an  influence  in  that  it  materially 
retards  dead-burning;  in  other  words,  an  amorphous  gypsum,  by  burn- 
ing, loses  the  setting  capacity  much  more  easily  than  a  half-hydrate 
of  well-developed  crystalline  structure. 

"  To  determine  this  fact  more  accurately  three  forms  of  gypsum 
were  used: 

"  1.  Well-developed  half-hydrate  obtained   by  nitric  acid. 

"2.  Alabaster  gypsum  of  commerce,  with  little  crystalline  develop- 
ment. 

"  3.  Gypsum  obtained  by  treating  a  stucco  gypsum  with  an  excess 
of  water,  leading  to  a  development  of  exceedingly  fine  needles,  which 
were  very  apt  to  lose  water  and  in  such  case  show  nothing  of  the  half- 
hydrate  form. 

"  These  samples  were  heated  for  about  five  minutes  on  a  gentle-red 
glow  in  the  platinum  crucible  and  then  sealed  up  with  a  slight  excess 
of  water  in  a  test-tube  and  left  to  harden.  After  about  twenty-four 
hours,  sample  No.  1  had  already  become  much  harder  and  showed  gyp- 
sum crystals  under  the  microscope;  the  other  two  samples  had  remained 
perfectly  soft  and  showed  no  change  under  the  microscope.  After  three 
days  the  first  sample  had  been  completely  hardened  and  entirely  trans- 
formed into  gypsum  crystals.  The  alabaster  gypsum  is  still  soft,  but 


FLOORING-PLASTERS  AND   HARD-FINISH  PLASTERS.  75 

may  be  slightly  harder  than  the  third  sample,  which  is  entirely  unaltered. 
Under  the  microscope  the  alabaster  gypsum  after  twelve  days  showed 
several  gypsum  crystals,  while  the  third  sample  showed  only  scattering 
ones. 

"  The  essential  result  of  the  investigation,  therefore,  is,  that  in  the 
heating  of  gypsum  after  total  dehydration,  which  occurs  at  about  190°, 
the  capacity  to  bind  water  is  at  first  retained,  and  is  only  gradually 
lost,  either  by  more  intense  or  by  longer  heating.  The  retention  of 
the  crystalline  form,  which  is  probably  due  to  burning  without  previous 
division  into  small  bits,  checks  this  so-called  dead-burning,  and  is  there- 
fore of  technical  importance.  We  found  no  evidence  to  support  the 
statement  that,  after  dead-burning,  a  new  binding  capacity  appears 
at  a  high  temperature,  in  which  case  even  the  natural  anhydrite  would 
be  suitable  for  burning  floor-gypsum." 

Methods  of  manufacture. — Flooring-gypsum  is,  therefore,  a  pure 
plaster,  entirely  free  from  water.  It  is  manufactured  by  burning  pure 
gypsum,  broken  into  lumps  but  not  finely  crushed,  in  a  vertical  kiln. 
The  fuel,  usually  coal,  is  burned  on  a  grate  set  at  one  side  of  the  kiln, 
and  the  hot  gases  pass  directly  through  the  mass  of  gypsum,  though 
neither  fuel  nor  ashes  come  into  direct  contact  with  it.  The  tempera- 
ture reached  is,  according  to  Wilder,  about  500°  C.  The  gypsum  must 
not  be  exposed  to  this  temperature  for  more  than  four  hours,  for  a 
longer  heating  would  deprive  it  entirely  of  its  setting  properties,  as 
noted  by  Van't  Hoff  in  the  paper  presented  above. 

Uses  of  flooring-gypsum.* — As  its  name  denotes,  flooring-gypsum 
(Estrichgips)  is  extensively  used  in  Germany  for  floors,  giving  a  very 
hard  and  durable  surface.  As  the  material  attains  this  hardness  only 
when  it  is  protected  from  moisture  during  setting,  care  must  be  taken 
to  give  it  a  suitable  foundation.  If  the  material  dries  unevenly  or 
very  rapidly  cracks  will  appear  on  its  surface.  In  this  case  the  floor 
should  be  covered  with  water  until  the  surface  is  soft  and  the  cracks 
closed,  after  which  it  is  allowed  to  dry  again.  After  standing  about 
twelve  hours  and  becoming  fairly  hard  the  floor  is  pounded  with  wooden 
mallets  and  smoothed  with  trowels. 

Pure  flooring-plaster  gives  the  best  results  for  hardness,  but  for 
economy  it  may  be  used  in  a  mixture  of  two  parts  plaster  to  one  part 
sand,  ashes,  etc.  A  cubic  meter  of  hardened  flooring-gypsum  weighs 
about  2000  Ibs.,  equivalent  to  a  weight  of  about  57  Ibs.  per  cubic  foot. 

Flooring-plasters  are  manufactured  on  a  fairly  large  scale  in  Germany, 
but  have  not  been  made  or  utilized  in  England  or  the  United  States. 


*  The  data  on  the  uses  of  flooring-gypsum  are  largely  taken  from  Wilder's 
paper,  cited  previously. 


76  CEMENTS,  LIMES,  AND   PLASTERS. 

Under  the  next  group  (Hard-finishing  Cements),  however,  will  be  found 
descriptions  of  a  number  of  products  which  have  been  manufactured 
in  these  latter  countries  and  which  are  very  closely  related  to  the  dead- 
burned  plasters.  The  only  difference  in  technology  between  the  two 
groups  is  that  while  the  flooring-plasters  are  prepared  from  pure  gypsum 
the  hard-finishing  cements  are  prepared  from  gypsum  to  which  alum 

or  some  similar  material  has  been  added. 

*  .  ** 

Hard-finish  Plasters. 

The  materials  grouped  under  this  name  include  those  plasters  which 
owe  their  hardness  and  slow  set  not  only  to  being  burned  at  high  tem- 
peratures, but  to  the  fact  that  they  have  been  treated  with  alum  or 
other  chemicals  during  manufacture.  As  thus  defined,  the  hard-finish 
plasters  include  the  various  materials  known  commercially  as  "Keene's 
cement",  "Parian  cement",  "Mack's  cement",  etc. 

Keene's  cement. — The  most  prominent  representative  of  the  group 
of  hard-finishing  cements  is  that  known  to  the  trade  as  Keene's  cement. 
Originally  manufactured  under  English  patents  which  have  now  ex- 
pired, the  term  "Keene's"  is  applied  by  various  manufacturers  to  their 
product,  in  the  same  manner  as  the  term  "Portland"  has  become  gener- 
alized. Large  quantities  of  Keene's  cement  are  annually  imported, 
while  its  manufacture  in  the  United  States  has  been  of  late  years  suc- 
cessively begun. 

Keene's  cement  is  sharply  distinguished  from  the  other  members 
of  the  group  of  hydrate  cements  (or  "plasters"),  not  only  by  the  proper- 
ties of  the  product,  but  by  its  method  of  manufacture.  In  its  prepara- 
tion a  very  pure  gypsum  is  calcined  at  a  red  heat,  the  resulting  dehy- 
drated lime  sulphate  is  immersed  in  a  bath  of  alum  solution  and,  after 
drying,  is  again  burned  at  a  high  temperature.  After  this  second  burn- 
ing the  product  is  finely  ground  and  is  then  ready  for  the  market.  This 
sketch  of  the  process  is  a  general  outline  of  the  methods  used,  and 
in  the  essentials  is  followed  in  all  plants,  though  slightly  modified  at 
different  plants  according  to  the  experience  gained  by  each  manufacturer. 

The  gypsum  used  should  be  as  pure  as  possible,  and  especially  it 
should  be  free  from  such  impurities  as  might  tend  to  discolor  the  product, 
which  should  be  a  pure  wjiite.  Nova  Scotia  gypsum  has  been  tried 
and,  for  some  reason,  found  to  be  unsatisfactory.  Even  the  Virginia 
gypsum,  which  on  analysis  shows  but  a  trace  of  iron  oxide,  is  not  en- 
tirely satisfactory;  for  on  heating  to  the  temperature  necessary  for 
the  manufacture  of  Keene's  cement,  minute  red  streaks  appear  in  the 


FLOORING-PLASTERS  AND  HARD-FINISH  PLASTERS.  77 

lumps  of  gypsum.  The  following  analyses  show  the  composition  of 
gypsum  from  Virginia  and  Kansas,  both  of  which  have  been  used  in 
the  preparation  of  a  domestic  Keene's  cement: 

Kansas.  Virginia. 

Lime  sulphate 77  46  ) 

Water. 20.46J 

Iron  and  aluminum  oxides 0.10  0 . 036 

Silica  and  insoluble 0.19  0.116 

Magnesium  carbonate 0 . 34  0 . 221 

Lime  carbonate 1 . 43 

It  will  be  seen  that  both  materials  are  very  pure  gypsums,  and  that, 
there  is  no  apparent  reason  why  the  Virginia  material  should  not  be 
as  satisfactory  as  that  from  Kansas. 

The  calcination  of  the  product  is  usually  carried  on  in  small  ver- 
tical kilns  closely  resembling  those  which  are  in  common  use  for  lime- 
burning.  These  kilns  are  charged  with  alternating  layers  of  fuel  (usu- 
ally coal)  and  lump  gypsum.  Small  rotary  kilns  have  been  used  experi- 
mentally, but  have  not  proven  successful,  as  the  calcined  product  from 
a  rotary  kiln  is  discharged  in  small  fragments  which  cannot  be  treated 
satisfactorily  in  the  alum-bath.  After  burning  to  a  red  heat  the  gyp- 
sum is  submitted  to  the  action  of  a  10  per  cent  alum  solution.  It  is 
then  recalcined  and  finally  ground  in  emery-mills. 

The  product  is  a  very  finely  grained  white  powder.  On  the  addi- 
tion of  water  this  cement  hardens,  but  the  hardening  is  slow  relative 
to  that  of  other  plasters.  Another  peculiarity  of  the  material  is  that 
even  after  the  hardening  has  commenced,  the  partly  set  cement  may 
be  reworked  with  water  and  will  take  its  set  just  as  satisfactorily  as 
if  the  process  of  hardening  had  not  been  interrupted. 

An  analysis  of  a  Keene's  cement  manufactured  in  Kansas  is  given 
in  "Tests  of  Metals,  etc.,  at  Watertown  Arsenal,  1897",  p.  403: 

Silica  (SiO2) tr. 

Alumina  (A12O3) tr. 

Iron  oxide  (Fe2O3) 

Lime  (CaO) ! 42.04 

Magnesia  (MgO) tr. 

Sulphur  trioxide  (SO3) 56 . 54 

Carbon  dioxide  (CO2) 1 . 37 

According  to  a  circular  issued  by  the  sales-agent  for  one  brand  the 
following  tests  of  two  brands  of 'Keene's  cement  were  made  by  Lath- 
bury  and  Spackman.  The  table  below  shows  the  tensile  strength 
obtained,  in  pounds  per  square  inch,  at  the  end  of  seven  days. 


78 


CEMENTS,  LIMES,  AND   PLASTERS. 


TABLE    21. 
TENSILE  STRENGTH  OF  KEENE'S  CEMENT. 


Maker. 

Grade. 

No.  1. 

No.  2. 

Superfine. 

Coarse. 

Improved    Keene    Cement 
Island  City,  N.  Y  

Co.,    Long 

548  Ibs. 
4QS     " 

606  Ibs. 
511     " 

680  Ibs. 

693  Ibs. 

J.  B.  White  &  Bro.,  London 

,  England.  . 

An  American  Keene's  cement  made  in  Kansas  was  tested  in  1892  by 
O.  S.  Carll  for  tensile  strength  with  the  following  results.  The  cement 
was  mixed  neat,  with  enough  water  to  make  a  stiff  plaster. 

TABLE    22. 
TENSILE  STRENGTH  OF  KEENE'S  CEMENT. 


24  Hours. 

7  Days. 

Specimen  No 

1 

374  Ibs 

630  Ibs 

U                     (t 

2  
3.  .  .     . 

325     " 
402     " 

698    " 
678    " 

Average  .  . 

367  Ibs 

669  Ibs 

Mack's  cement  *  consists  of  dehydrated  gypsum  (flooring-plaster) 
to  which  0.4  per  cent  of  calcined  sodium  sulphate  (Na2SO4,  Glauber's 
salts)  or  potassium  sulphate  (K2S04)  has  been  added.  "  This  cement 
is  unusually  hard  and  durable,  sets  quickly  and  unites  minutely  with 
the  material  on  which  it  is  placed.  It  is  used  as  a  covering  for  wire 
mesh  on  walls  and  ceilings,  as  well  as  for  floors,  and  may  be  mixed  with 
sand  or  ashes.  Its  surface  is  but  slightly  porous  and  for  this  reason 
absorbs  but  little  oil  when  covered  with  paint." 

References  on  dead-burned  and  hard-finish  plasters. 
Eckel,  E.  C.     Plasters  and  hard-finishing  cements  in  the  United  States.     En- 
gineering News,  vol.  49,  pp.  107,  108.     Jan.  29,  1903. 
Grimsley,  G.  P.     [Hard-finish  plasters.]    Vol.  5,  Reports  Kansas  Geological 

Survey,  pp.  115-118.     1899. 

Redgrave,  G.  R.     Calcareous  cements.     London,  1895.     Pp.  196-199. 
Rohland.  P.     [Influence  of  catalysers  on  velocity  of  hydration  of  plasters,  etc.] 
Zeitschrift    anorganische    Chemie,  vol.   31,  pp.   437-444.     Abstract  in 
Journ.  Soc.  Chem.  Industry,  vol.  21,  p.  1233.     1901. 

Van't  Hoff  and  Just,  G.  Der  hydraulische  oder  sogenannte  Estrichgips. 
S:tzungsberi elite  der  Kgl.  Preuss.  Akad.  der  Wissenschaften,  1903, 
vol.  1,  pp.  249-258. 

Wilder,  F.  A.  The  gypsum  industry  of  Germany.  Vol.  12,  Reports  Iowa 
Geological  Survey,  pp.  192-223.  1902. 

*  Wilder,  F.  A.  Gypsum  industry  of  Germany,  p.  208,  vol.  12,  Reports  Iowa 
Geol.  Survey.  1902. 


CHAPTER  V. 
STATISTICS  OF  THE  GYPSUM  AND  PLASTER  INDUSTRIES. 

THE  statistics  presented  in  this  chapter  are  those  collected  by  Mr. 
G.  I.  Adams,  of  the  U.  S.  Geological  Survey,  for  the  annual  report  on 
"  Mineral  Resources  of  the  United  States  "  issued  by  that  organization. 
They  have,  however,  been  condensed  and  rearranged  in  order  to  better 
serve  the  purposes  of  this  volume. 

Total  TTse  of  Gypsum  in  the  United  States. 

The  total  amount  of  gypsum  used  in  the  United  States  for  the 
four  years  1900-1903,  inclusive,  is  given  in  the  following  table.  The 
total  given  in  the  last  column  of  this  table  includes  the  gypsum  imported 
as  well  as  that  produced  in  the  country. 

TABLE    23. 
TOTAL  IMPORTS  AND  PRODUCTION  OF  GYPSUM. 


Year. 

Produced  in 
U.S. 
Short  Tons. 

Imported.* 
Short  Tons. 

Total  Tons. 

1900  

594,462 

229,432 

823,894 

1901  

633,791 

223,381 

857,172 

1902 

816  478 

290  858 

1  107  336 

1903 

1  041  704 

323  431 

1  365  135 

*  In  the  Survey  report  above  quoted  the  imports  are  given  in 
long  tons.     They  have  here  been  reduced  to  tons  of  2000  Ibs. 

This  total  amount  of  gypsum  was  distributed  about  as  follows  to 
the  two  principal  uses.  The  term  calcined  plaster  as  here  used  includes 
all  the  grades  of  plaster  of  Paris,  cement  plaster,  wall-plaster,  hard- 
finish  plasters,  etc. 

TABLE    24. 
USES  OF  GYPSUM. 


Year. 

Calcined. 

Used  Crude 
as  Fertilizer. 

1900  .  . 
1901 

742,733 
729  445 

81,161 
127  727 

1902  
1903  

965,090 
1,216,622 

142,246 
148,513 

79 


80 


CEMENTS,  LIMES,  AND  PLASTERS. 


II 


CO  TH  (M 

C^l  *O  O^ 

"I  o  ;£ 

1C  CO  CO 


CO 
CO       1> 


b-  CO 
OS  1>- 
1>  to 


o  o 

00  00 

^1  0, 

1C  00 


4s*        CO 
CO         O 

CO         to 


CO  OS 

oT  <N" 

00  OS 

o^  t^ 

<N"  co" 


s 


O        00        OS 

tC  TF  Ttf 


(M       OS 

**  TP 


H^         CO        CO        CO        CO 


b-        CO 

CO        CO 


i—t  1C  00. 

CO  O  TfH 

co_  o_  TJH 

oo"  <N"  oo" 


CO'        CO 

%   § 

1C          CO 


TH  TH  CO  TH 

CO         CO         O        CO 

TJH  b-  CO  >O 


^          H/i          rH          t>*          OS 

b»          OS          CO          tO          rH 


O  t^ 

CN^  CO^ 

o"  tc" 

O  CO 

tC  CO 


o  o 

OS  OS 

-1  w 

OS  O 


oo 

00 


1C 
TH"       co" 


1>        00 

CO        iO 
O5         i—  ' 


TH        1C        1C        CO 


O        CO 

TH  O 


o      o 

00         OS 


CO        OS 
OS       OS 


OS        C-1 

CO  Tfl 

tC        I> 


^   M  a  oo 

j*  0  S  O  CM 

^o'H  !  ^  ^ 

•StM-rt  tT   r^ 


oo^     tc^ 

CO        »0 


TH  TH  CO 


r^  £ 


co      co      tc 


i  S 

bt      of 

CO         (30 


EC* 

>(!, 

•< 


§5  ^  §5 


CO  00  CO  CO  rH 

Tf  rH  rH  CO  O 


rH          1C 

oo      oo 


tC        00 
I>        O 


u 


C*          rH          rH          rH          CO 


c^     co_     co^ 

co"     i>~     co" 

"tf  rH  O 


CO         O5 

co"     ic" 
o      os 


« 

<M 


O        CO        tc        OS        O 


CO        CO         CO 


CO        O 

to"       os" 

H/l  iO 


OS 


0 

CO 


O        "tf 
CO       1> 


tC       OS 


OS        00 

rH  CO 


^     o     2 

OS  {£, 

^     «2.     ^ 


g  2  §  §1 


t*-       OS       co 

*    r-T         CO"         l>" 

t>      os      oc 


H^        00        CO        OS        OS        1C        CO 

CO  tO  1C  l>  CO  »C  rH 


*s    !>_         «^ 

_         o  oo"     oo 

a    IS^    ^ 


CO^       CO_       TH^       t>^       CO^       TJH 

co"     i>^     co"     to"     oo"     to" 

CO        TH        (N 


OS 

T-"  CO 

CO        CO        00        b- 


1C 


-1   N 

00        CO 


§8    3 


CO  rH 

CO       OS 
CO        (N        «tf        b- 


00         "T 
l>        O 


^  9  § 


oo 


CO          CO          rH 


rH  C<l  CO 

§s    s. 
OS       OS 


STATISTICS  OF   THE  GYPSUM  AND  PLASTER  INDUSTRIES.      81 

Production  in  the  United  States,  by  Uses,  1890-1903. — In  Table  25, 
the  gypsum  production  of  the  United  States  is  given  for  the  years  1890 
to  1903  inclusive,  classed  according  to  uses  as  accurately  as  possible. 
It  will  be  seen  that  the  amount  ground  up  and  sold  as  land  plaster  has 
increased  but  slightly  during  the  period  covered  by  the  table.  The 
production  of  calcined  plaster,  on  the  other  hand,  was  almost  seven 
times  as  great  in  1903  as  in  1890. 

Production  in  the  United  States,  by  States  and  classes  of  product, 
1902-1903. — At  present  the  gypsum  industry  is  carried  on  commercially 
in  twenty-two  states  and  territories,  which  are  named  in  the  order 
of  their  importance  as  producers:  Michigan,  New  York,  Iowa,  Texas, 
Ohio,  Oklahoma,  Kansas,  Wyoming,  Colorado,  Utah,  Virginia,  Cali- 
fornia, South  Dakota,  Nevada,  Montana,  Oregon,  and  New  Mexico. 
The  other  five  states  do  not  produce  gypsum,  but  contain  large 
plants  to  which  the  raw  material  is  shipped  from  other  states  and  from 
foreign  countries,  and  converted  into  wall-plaster  and  plaster  of  Paris . 

In  table  26,  which  shows  the  production  of  gypsum  by  states  for 
1902  and  1903,  it  has  been  necessary  to  combine  the  output  of  certain 
states  in  which  there  are  less  than  three  producers  in  order  to  protect 
individual  statistics. 


82 


CEMENTS,  LIMES,  AND  PLASTERS. 


CO  1>  *C  04  CO  rH  OJ 

rH  Tf  Tfrl  rH  OO  OI  OI 

rH  CO  O  Oi  CO  CD  »C 

CO 

«-H      £ 

CO  Ol  1C  rH  O  «C  1C 

CO  CO  CO  CD  ^  01  Ol 

CO 

i 

! 

t^  co  t^  ooa  «t  i> 

CD  co  oo  o  CD  co  o 

^rHO^t- 

Oi 

co" 

•S  ~ 

O  CO  1>  O  Oi  rH  OO 

O  l>  O  *C  >C  rH  00 
<M        00  TJI  01  rH 

O5 

•a 

r^  Is-  O4  CO  Ol  O^  OI 

00  00  Oi  O  *C  J>  T^I 

1 

i 

g 

CO  Ol  00  rH  CD  1C  »C 

1C  J>  !>•  O4  CO  rH  rH 

i—i  CO  CD  00  Ol  Ol  l> 

i 

Blaster  ai 
iris. 

1 

oToT^  rH   O5  CO  |> 

Isisssaa. 

« 

CO 

• 

2 

00  CO  Oi  01  O  rH  CO 
Ol          I>  CO  CM  rH 

i 

So 

rH 

^ 

&° 

»l 

§    lCJ>-I>-OJrHTtliC 

-^    rHOOOrHCDOCD 

CO 

1* 

A 

-  G 

3"c 

2    CO  rH  1C  CD  Tf  1C  CO 

§  cDr^ooicocoqco 

-*^    O4   00  CO  CD  rH   CO  t^* 

1 

i 

3S 

S| 

51 

o 

Jb-O^cD^Oi 

1 

02 

1 

ll 

g 

O    CDrHCOOlCDOQrH 

co   K 

Oi 

1 

1 

1 

a6* 

§    S^rHrHCOlCOq 

Oi 

1 

1 

•« 

ii 

2    OOrHrHCCCDCD 

O   (N  1C  OC  O?  CO  1C  CD 

*>    OOOtCOOarHrH 

w 

pq 

co" 

a 

81 

O 

O   GO  CO  Cb  O^  O^  ^O  ^"^ 

g                    O^rH 

g 

oo 

W 
Ol" 

3 

2| 

|S32|SKSS 

i 

o 

rH 

5 

cc 
W 

i 

1 

§O  Ol  Oi  Ol  OI  O 
O  **  ^  Oi        O 

!>•  ^C  OQ  Oi  CO          rH 

TJH"       cD"l>TtC       oo" 

co          oq  i> 

1C 

I 

rH 

TJ 

1. 

1 

o    :^^g    :§ 

ic"    •  CD  CD  CO"    |  -^ 

CD" 

.1 

p 

1 

02 

C  tC  O  £D  Oi  O  rH  O 

.2  o  o  i>  o  »c      o 

^a    O  rH  Oi  Tfl  00           Ol 

rH 

8 

1 

r 

c 

02 
C    I>        •  rH   O}   rH        '  O 

_o  ic    •  co  oi  oo    •  c 

£    CO       •  CO  O  Oi       •  rH 

rH 

TV]          £* 

o 

3 

o  co"     O4  oo"t^     01 

^    rH                   rH  CO 
CO 

21 

Q 
g 

o 

c§ 

fe    CD       .  Tfi  CO  »C       .  rH 

_°    rH        .          rH  O5       . 
CO 

i 

3 

CO        CD  O  CO  t^  O 
1C        00  Oi  ^f  00  O 

00 

H 

§    ;oo  o  oo    ;  o 

Oi 

H   g 

1 

3 

&$          rH  1C  rH 

£ 

M 

flj 
-o 

1 

CD        .rH  O  1C       . 

g 

a 

1 

s 

03 
O    IN.           00  >C  TfH  00  O 

3  CO        O  CD  O  Oi  O 
^  CO        Ol  1C  CO  CD  00 

Ol 

rH 
Oi 

CO 

c 

3J 

CO      •  1>  IT1-  CO      '  O 

0  CD     •  1C  00  »C      •  O 

^    CO        'CiOO  rH        •  rH 

•* 

1 

I 

0   1-1        OTOQ  Oi 

s 

$ 

1 

J  N  :    CD0  i 

02 

00 

o 

fe 

o 

"3; 

>, 

iillllSl 

I 

O 

0 

$ 

§•>*  1C  CD  OJ  O  1C  CD 
^    LCOt^05COrHCO 

00 

£ 

43 

5 

^  co  co  i>-  o>  r^»  Oi  i—  i 

£ 

f: 

M 

i 

^    rHCD>COC^OO 

CD 

0 

i 

( 

§ 

^    rH          CO01  rH          rH 

CO 

0 

rH 

o 
| 

c 

1 

m 

00 

p 

OH 

p  . 

PH 

°3     .!.... 

! 

i 

"Sc  *  ^ 

—    vX  03 

.^  ou  ,> 

i 

1 

5   .  •   •   •  •  • 

* 
j 

j 

i 

I 
1 

5 

California,  Ohio,  and  "V 
Colorado  and  Wyomir 
Iowa,  Kansas,  and  Te: 
Michigan  
New  York  
Oklahoma  
Other  states  

i 

1 

i 
£ 

I 

! 

California,  Ohio,  and  A 
Colorado  and  Wyomin 
Iowa,  Kansas,  and  Te: 
Michigan  
New  York  
Oklahoma  
Other  states  

i 

STATISTICS  OF  THE  GYPSUM  AND  PLASTER  INDUSTRIES.      83 


Production  by  States,  1890-1901. — In  Table  27  the  amounts  and 
value  of  the  gypsum  production,  arranged  by  states,  is  given  for  the 
years  1890  to  1901  inclusive.  During  this  period  much  of  the  growth 
in  the  gypsum  industry  took  place  in  the  Western  States;  while  Texas 
and  Oklahoma  entered  the  list  of  producers.  More  recently  the  gypsum 
industry  has  renewed  its  activity  in  New  York  and  Michigan. 

TABLE  27. 
PRODUCTION  AND  VALUE  OF  GYPSUM  BY  STATES,  1890-1901. 


State. 

1890. 

1891. 

1892. 

Quantity. 

Value. 

Quantity. 

Value. 

Quantity. 

Value. 

California  
Colorado 

Short  tons. 
4,249 
4,580 
20,900 
20,250 
74,877 
32,903 
12,748 
2,9CO 

$29,178 
22,050 
47,350 
72,457 
192,099 
73,093 
87,533 
7,750 

Short  tons. 
3,000 
4,720 
31,385 
40,217 
79,700 
30,135 
9,123 
3,615 

$36,360 
19,400 
58,095 
161,322 
223,725 
58,571 
36,586 
9,618 

Short  tons. 

1,500 
12,000 
46,016 
139,557 
32,394 
13,275 

1,926 
2,600 
6,991 

$1,500 
28,500 
195,197 
306,527 
61,100 
49,521 

8,640 
16,300 
28,207 

Iowa             

Kansas     

Michigan        

New  York   

Ohio           

South  Dakota.  .  .  . 
Texas  

Utah    

3,000 
5,959 
1,992 

15,000 
22,574 
6,200 

Virginia   

6,350 
3,238 

20,782 
22,231 

"Wyoming     

Total  

182,995 

574,523 

212,846 

647,451 

256,259 

695,492 

State  or  Territory. 

1893. 

1894. 

1895. 

Quantity. 

Value. 

Quantity. 

Value. 

Quantity. 

Value. 

California    

Short  tons. 

Short  tons. 

6 
895 

$30 
4,800 

Short  tons. 
5,158 
1,371 
13,100 
25,700 
72,947 
66,519 

33,587 
21,662 

6,400 
10,750 
2,134 
5.800 
375  ' 

$51,014 
8,281 
46,125 
36,600 
272,531 
174,007 

59,321 
71,204 

20,600 
36,511 
11,484 
17,369 
2,400 

Colorado          .... 

Indian  Territory. 

Iowa       

21,447 
43,631 
124,590 

$55,538 
181,599 
303,921 

17,906 
64,889 
79,958 
175 
31,798 
20,827 
1,300 
4,295 
6,925 
1,920 
8,106 
312 

44,700 
301,884 
189,620 
1,820 
60,262 
69,597 
7,500 
16,050 
27,300 
12,225 
24,431 
1,500 

Kansas     

Michigan  
Montana 

New  York  
Ohio 

36,126 
11,646 

65,392 
39,884 

Oklahoma 

South  Dakota.  .  .  . 
Texas     

5,150 
4,011 

12,550 
13,372 

Utah     

Virginia 

7,014 

24,359 

Wyoming 

Total  

253,615 

696,615 

239,312 

761,719 

265,503 

807,447 

CEMENTS,  LIMES,  AND   PLASTERS. 


TABLE  27 — (Continued). 
PRODUCTION  AND  VALUE  OF  GYPSUM  BY  STATES,  1896-1901. 


State  or  Territory. 

1896. 

1897. 

1898. 

Quantity. 

Value. 

Quantity. 

Value. 

Quantity. 

Value. 

Arizona  

Short  tons. 

Short  tons. 

^   30 
:   351 
1,575 
10,734 
29,430 
54,353 
94,874 
425 
33,440 
18,592 

$250 
2,774 
10,305 
40,050 
64,900 
189,679  * 
193,576 
2,3CO 
78,684 
50,856 

Short  tons. 
30 
3,8CO 
165 

24,733 
59,180 
93,181 
1,123 
31,655 
21,303 
3,150 
150 
2,740 
34,215 
2,610 
8,378 
5,225 

$700 
24,977 
726 

45,819 
191,389 
204,310 

7,272 
81,969 
61,884 
12,000 
450 
9,200 
58,130 
10,080 
23,388 
22,986 

Califorina  

1,452 
1,600 
8,000 
18,631 
49,435 
67,634 
385 
23,325 
22,634 

$11,738 
10,547 
24,000 
34,020 
148,371 
146,424 
1,940 
32,812 
63,583 

Colorado  
Indian  Territory.  . 
Iowa 

Kansas  
Michigan      

Montana  
New  York   

Ohio         

Oklahoma  

Oregon 

South  Dakota.  .  .  . 
Texas  
Utah       

6,115 
16,022 
2,866 

5,955 
200 

20,OCO 
48,070 
13,CCO 
17,264 
975 

8,350 
24,454 
2,700 
6,374 
3,3CO 

19,240 
65,651 
13,500 
16,899 
7,200 

Virginia  
Wyoming  

Total  

224,254 

573,344 

288,982 

755,864 

291,638 

755,280 

State  or  Territory. 

1399. 

1900. 

1901. 

Quantity. 

Value. 

Quantity. 

Value. 

Quantity. 

Value. 

Arizona        

Short  tons. 
47 
2,950 
871 
12,000 
75,574 
85,046 
144,776 
582 
52,149 

$1,200 
14,950 
3,904 
26,000 
296,220 
247,690 
283,537 
3,698 
105,533 

Short  tens. 

35 

3,280 
967 
6,500 
184,600 
48,636 
129,654 
1,025 
58,890 
1,000 
39,034 
18,437 
550 
2,050 
80,622 
2,397 
11,940 
4,845 

$900 
10,088 
5,300 
15,000 
561,588 
150,257 
285,119 
7,980 
150,588 
4,805 
119,946 
60,380 
1,710 
13,800 
192,418 
4,984 
18,111 
24,229 

Short  tons. 

3,550 
13,291 

63,653 
69,390 
185,150 

119,565 
15,930 

80,376 

15,236 
4,103 
63,547 

$4,200 
64,772 

160,788 
213,260 
267,243 

241,669 
66,031 

255,288 

45,144 
11,663 
176,583 

California  
Colorado  
Indian  Territory.  . 
Iowa 

Kansas  
Michigan        

Montana          .... 

New  York   

Ohio         

27,205 
11,526 
550 
550 
53,773 
2,352 
11,480 
4,804 

73,520 
36,600 
1,895 
4,000 
125,000 
10,240 
32,043 
21,050 

Oklahoma  
Oregon.  
South  Dakota  .  .  . 
Texas  
Utah 

Virginia     . 

Wyoming  
Other  states    .  .  .  . 

Total    ' 

486,235 

1,287,080 

594,462 

1,627,203 

633,791 

1,506,641 

Imports  of  Gypsum  and  Plaster. — Table  28  contains  statistics  relative 
to  the  amount  of  gypsum,  etc.,  entering  the  different  customs  districts. 


STATISTICS   OF  THE  GYPSUM  AND  PLASTER  INDUSTRIES.      85 


oo 


*  II 

g  SMrf 

3      «  o 

B  fi 

S    ft  § 
P   o  ^ 

°         o 

fa     /w"  2 

o    ^2 

1  i* 

g  ag 

S   |5 

I 

I 
§ 


<N 
OS 


00  00  TF  t>-  00  00  I-H  Tf  CO  O  O  CO 
00  i—  I  b-  id  CO  <M  O  CO  rfi  <N  O  CO 
COOO  OOO  »OOO  ^  00  I>  CO  iO  CO 


>>        g   O  CO  CO  CO        O        TF  (N  00  rH  O  CO  »O  (M  »O  O'*  <M 

ai  I 


CO 
(M 


1>         r-  rtOft^rUS 

1-1  CO  O*        <N 


ooo  cooo 
'oif  i-TuftC 


O(M 
Ot> 


) 

g 


rH  O^  1^   ^   O  t^*  "^  O^  O1  00 

CQt**GCQQ*       co"^" 

CO  CO          CO 

' 


O»OO»OO50COO 
COCOCOrHO500r-i 
CO 


O 
O 


CO1>  OCO  COI-H  COiO~rH 
10  CO     .  CO 


O     •  O  O  »0  O5  1C  (M 

c^    'coojcocooico 

Tt      •  O5  Tf  Oi  00  1>  CO 


O 

(N 


CO-^1  00CO<M 

00  CO          ^O 


OOfNiOOOi 

rH    O   CO  TfH   rH   T^ 

COOOfNCOCiOO 


CO 

CO 


r^  CO  1C 

oo  i—  i  o 

"t  iO  CO 


§ss 

N  iff  CO* 


O 
C^ 


CEMENTS,  LIMES,  AND  PLASTERS. 


In  Table  29  the  imports  for  the  years  1900  to  1903  inclusive  are 
given,  classified  according  to  the  countries  from  which  the  products 
come.  The  amounts  credited  to  Nova  Scotia  and  New  Brunswick  are 
made  up  of  crude  gypsum.  The  imports  from  France  and  England, 
on  the  other  hand,  are  almost  entirely  of  the  higher  grades  of  finished 
plasters,  as  is  shown  by  the  high  valuation  per  ton. 

Comparison  of  Tables  29  and  SOjehows  that  almost  two-thirds  of 
the  entire  gypsum  production  of  Canada  is  sent  into  the  United  States 
as  crude  gypsum.  This  heavy  importation  has  exercised  an  important 
influence  in  delaying  the  development  of  the  New  »York  and  Virginia 
gypsum  deposits,  which  are  located  near  enough  to  tidewater  to  suffer 
from  the  competition. 

TABLE  29. 

IMPORTS  OF  CRUDE,  GROUND,  OR  CALCINED  (DUTIABLE)  GYPSUM,  BY  COUNTRIES,  IN 
THE  FISCAL  YEARS  ENDING  JUNE  30,  1900,  1901,  1902,  AND  1903. 


Country  from  which  Imported. 

1903. 

1902. 

Quantity. 

Value. 

Quantity. 

Value. 

France   

Long  tons. 

57 
333 

288,366 

22 

$395 
5,422 
319,497 

371 

Long  tons. 

132 
190 
259,353 

20 

$1,902 
1,854 

275,877 

23 

United  Kingdom 

Nova  Scotia  and  New  Brunswick  .  . 
Mexico                 

Other  countries  

Total  

288,778 

325,685 

259,695 

279,656 

Country  from  which  Imported. 

1901. 

1900. 

Quantity. 

Value. 

Quantity. 

Value. 

France   

Long  tons. 
185 

93 

196,932 
2,236 
1 

$1,311 

987 
216,636 
9,700 
36 

Long  tons. 
342 
59 
203,347 
1,014 
88 

$2,397 
836 
234,563 
4,500 
602 

United  Kingdom 

Nova  Scotia  and  New  Brunswick.  . 
Mexico                 

Total  

199,447 

228,670 

204,850 

242,898 

World's  Production  of  Gypsum. 

The  United  States  is  the  second  country  in  the  world  in  the  produc- 
tion of  gypsum,  France  being  the  first.  Canada  is  third,  Great  Britain 
fourth,  and  Germany  fifth.  In  the  following  table  the  production  of 
the  various  countries  since  1893  is  set  forth: 


STATISTICS  OF  THE  GYPSUM  AND  PLASTER  INDUSTRIES.       87 


TABLE  30. 
THE  WORLD'S  PRODUCTION  OF  GYPSUM,  1893-1903. 


Year. 

France. 

United  States. 

Canada. 

Quantity. 

Value. 

Quantity. 

Value. 

Quantity. 

Value. 

1893 

Short  tons. 

Short  tons. 
253,615 
239,312 
265,503 
224,254 
288,982 
291,638 
486,235 
594,462 
633,791 
816,478 
1,041,704 

$696,615 
761,719 
797,447 
573,344 
755,864 
755,280 
1,287,080 
1,627,203 
1,506,641 
2,089,341 
3,792,943 

Short  tens. 
192,568 
223,631 
226,178 
207,032 
239,691 
219,256 
244,566 
252,001 
293,879 
332,045 
307,489 

$196,150 
202,031 
202,608 
178,061 
244,531 
230,440 
257,329 
259,009 
340,148 
356,317 
384,259 

1894 

1,693,831 
2,175,448 
1,866,498 
1,845,874 
1,931,712 
1,802,812 
1,761,835 
2,182,229 
1,975,513 
* 

$2,891,365 
3,392,768 
2,661,200 
2,673,033 
2,777,816 
2,641,020 
2,772,221 
3,449,747 
3,318,070 
* 

1895 

1896   .    ... 

1897   

1898  
1899   

1900   

1901 

1902  

1903  

Year. 

Great  Britain. 

German  Empire. 

Algeria. 

Quantity. 

Value. 

Quantity. 

Value. 

Quantity. 

Value. 

1893 

Short  tons. 

158,122 
169,102 
196,037 
213,028 
203,151 
219,549 
238,071 
233,002 
224,919 
251,629 
* 

$287,940 
321,822 
348,400 
361,509 
325,513 
345,882 
372,073 
348,210 
344,650 
384,263 
* 

Short  tons. 

Short  tons. 

36,355 
50,127 
41,350 
40,510 
41,156 
44,037 
41,446 
38,955 
J  6,889 
* 

$114,900 
133,226 
114,361 
109,648 
110,660 
117,895 
139,190 
132,286 
52,253 
* 

1894 

1895 

23,994 
31,736 
28,821 
28,315 
32,760 
39,103 
f35,013 
34,944 
* 

$11,040 
14,598 
13,228 
13,166 
19,660 
17,199 
1  23,139 
12,732 
* 

1896 

1897   .    .  . 

1898   .    ... 

1899   

1900  

1901  

1902  

1903 

Year. 

India. 

Cyprus. 

Quantity. 

Value. 

Quantity. 

Value. 

1893 

Short  tons. 

Short  tons. 
2,357 
3,104 
2,093 
1,050 
4,167 
4,279 
4,402 

7,784 

7,874 
* 

$6,625 
9,006 
5,252 
2,590 
8,162 
7,551 
8,866 

17,041 
17,443 

* 

1894   

3,548 
7,511 
8,248 
9,025 
9,249 
7,216 
4,865 
* 
* 
* 

$1,566 
2,987 
3,130 
3,333 
1,503 
768 
424 
* 
* 
* 

1895  

1896  

1897  

1898  

1899       

1900   

1901   

1902   

1903  

*  Not  yet  available. 


t  Includes  Baden. 


Includes  Tunis. 


PART  ft.     LIMES. 


CHAPTER  VI. 

COMPOSITION,   ORIGIN,   AND  GENERAL  CHARACTERS  OF 
LIMESTONES. 

LIMESTONE  is  the  raw  material  on  which  is  based  the  manufacture 
of  lime,  and  it  is  also  the  most  important  ingredient,  in  one  form  or 
another,  in  a  Portland-cement  mixture.  Further,  impure  limes-tones 
of  certain  types  are  employed  in  the  manufacture  of  hydraulic  limes 
and  natural  cements.  It  will  thus  be  seen  that  limestone  plays  a  very 
important  part  in  the  manufacture  of  nearly  all  the  cementing  materials 
discussed  in  this  volume,  only  the  plasters  (Chapters  I-V)  being  manu- 
factured without  its  use. 

For  this  reason  it  has  seemed  desirable  to  discuss  in  the  present 
chapter  the  origin,  composition,  varieties,  and  chemical  and  physical 
characters  of  limestone  in  general.  This  has  been  done  in  considerable 
detail.  The  present  chapter  will  therefore  serve  as  an  introduction 
not  only  to  the  limes  but  to  the  hydraulic  limes  and  the  natural  and 
Portland  cements.  More  detailed  statements  concerning  the  special 
kinds  of  limestone  required  in  the  different  industries  will  be  found  in 
the  sections  on  those  industries,  particularly  in  Chapters  XXIII-XXV  of 
the  section  on  Portland  cement. 

Origin  of  limestones.* — Limestones  have  been  formed  largely  by 
the  accumulation  at  the  sea-bottom  of  the  calcareous  remains  of  such 
organisms  as  the  foraminifera,  corals,  and  mollusks.  Many  of  the  thick 
and  extensive  limestone  deposits  of  the  United  States  were  probably 
-deep-sea  deposits  formed  in  this  way.  Some  of  these  limestones  still 
show  the  fossils  of  which  they  were  formed,  but  in  others  all  trace  of 

*  For  a  more  detailed  discussion  of  this  subject  the  reader  will  do  well  to 
consult  Chapter  VIII  of  Prof.  J.  F.  Kemp's  "Handbook  of  Rocks". 

88 


117°  113 


UNITED  STATES 


FIG.  19. 


[To  face  p. 


LIMESTONES.  89 

organic  origin  has  been  destroyed  by  the  fine  grinding  to  which  the 
shells  and  corals  were  subjected  before  their  deposition  at  the  sea- 
bottom.  It  is  probable  also  that  part  of  the  calcium  carbonate  of 
these  limestones  was  a  purely  chemical  deposit  from  solution,  cementing 
the  shell  fragments  together. 

A  far  less  extensive  class  of  limestones,  though  very  important  in 
the  present  connection,  owe  their  origin  to  the  indirect  action  of  or- 
ganisms. The  "  marls ",  so  important  to-day  as  Portland-cement 
materials,  fall  in  this  class.  As  the  class  is  of  limited  extent,  however, 
its  method  of  origin  may  be  dismissed  here,  but  will  be  described  later  in 
the  chapter  on  marls,  pages  '334-347. 

Deposition  from  solution  by  purely  chemical  means  has  undoubtedly 
given  rise  to  numerous  important  limestone  deposits.  When  this  depo- 
sition took  place  in  caverns  or  in  the  open  air  it  gave  rise  to  onyx 
deposits  and  to  the  " travertine  marls7'  of  certain  Ohio  and  other  locali- 
ties; when  it  took  place  in  isolated  portions  of  the  sea  through  the 
evaporation  of  the  sea-water  it  gave  rise  to  the  limestone  beds  which 
so  frequently  accompany  deposits  of  salt  and  gypsum. 

Varieties  of  limestone. — A  number  of  terms  are  in  general  use  for 
the  different  varieties  of  limestone,  based  upon  differences  of  origin, 
texture,  composition,  etc.  The  more  important  of  these  terms  will  be 
briefly  defined. 

The  marbles  are  limestones  which,  through  the  action  of  heat  and  pres- 
sure, have  become  more  or  less  distinctly  crystalline.  -  The  term  marl  as 
at  present  used  in  cement  manufacture  is  applied  to  a  loosely  cemented 
mass  of  lime  carbonate  formed  in  lake  basins  as  described  in  more  detail 
in  Chapter  XXV.  Calcareous  tufa  and  travertine  are  more  or  less  com- 
pact limestones  deposited  by  spring  or  stream  waters  along  their  courses. 
Oolitic  limestones,  so  called  because  of  their  resemblance  to  a  mass 
of  fish-roe,  are  made  up  of  small  rounded  grains  of  lime  carbonate.  Chalk 
is  a  fine-grained  limestone  composed  of  finely  comminuted  shells,  par- 
ticularly those  of  the  foraminifera.  The  presence  of  much  silica  gives 
rise  to  a  siliceous  or  cherty  limestone.  If  the  silica  present  is  in  com- 
bination with  alumina,  the  resulting  limestone  will  be  clayey  or  argil- 
laceous. 

Chemical  composition  of  limestone. — A  theoretically  pure  limestone 
is  merely  a  massive  form  of  the  mineral  calcite.  Such  an  ideal  lime- 
stone would  therefore  consist  entirely  of  calcium  carbonate  or  carbonate 
of  lime,  with  the  formula  CaCO3[CaO  +  CO2],  corresponding  to  the  com- 
position calcium  oxide  (CaO)  56  per  cent,  carbon  dioxide  or  carbonic 
acid  (CO2)  44  per  cent. 


90  CEMENTS,  LIMES,  AND  PLASTERS. 

As  might  be  expected,  the  limestones  we  have  to  deal  with  in  practice 
depart  more  or  less  widely  from  this  theoretical  composition.     These 
departures  from  ideal  purity  may  take  place  along  either  of  two  lines: 
a.  The  presence  of  magnesia  in  place  of  part  of  the  lime  ; 
6.  The  presence  of  silica,  iron,  alumina,  alkalies,  or  other  im- 
purities. 

It  seems  advisable  to  -discriminate  between  these  two  cases,  even 
though  a  given  sample  of  limestone  may  fall  under  both  heads,  and 
they  will  therefore  be  discussed  separately. 

The  presence  of  magnesia  in  place  of  part  of  the  lime. — The  theo- 
retically pure  limestones  are,  as  above '  noted,  composed  entirely  of 
calcium  carbonate  and  correspond  to  the  chemical  formula  CaCOs. 
Setting  aside  for  the  moment  the  question  of  the  presence  or  absence 
of  such  impurities  as  iron,  alumina,  silica,  etc.,  it  may  be  said  that 
lime  is  rarely  the  only  base  in  a  limestone.  During  or  after  the  forma- 
tion of  the  limestone  a  certain  percentage  of  magnesia  is  usually  intro- 
duced in  place  of  part  of  the  lime,  thus  giving  a  more  or  less  magnesian 
limestone.  In  such  magnesian  limestones  part  of  the  calcium  car- 
bonate is  replaced  by  magnesium  carbonate  (MgCOs),  the  general 
formula  for  a  magnesian  limestone  being,  therefore, 

zCaCOs  +  2/MgCOs. 

In  this  formula  x  may  vary  from  100  per  cent  to  zero,  while  y  will 
vary  inversely  from  zero  to  100  per  cent.  In  the  particular  case  of 
this  replacement  where  the  two  carbonates  are  united  in  equal  molec- 
ular proportions,  the  resultant  rock  is  called  dolomite.  It  has  the 
formula  CaCOs, MgCOs,  corresponding  to  the  composition  calcium 
carbonate  54.35  per  cent,  magnesium  carbonate  45.65  per  cent.  In 
the  case  where  the  calcium  carbonate  has  been  entirely  replaced  by 
magnesium  carbonate,  the  resulting  pure  carbonate  of  magnesia  is 
called  magnesite,  having  the  formula  MgCOs  and  the  composition  mag- 
nesia (MgO)  47.6  per  cent,  carbon  dioxide  (CO2)  52.4  per  cent. 

Rocks  of  this  series  may  therefore  vary  in  composition  from  pure 
calcite  limestone  at  one  end  of  the  series  to  pure  magnesite  at  the  other. 
The  term  limestone  has,  however,  been  restricted  in  general  use  to  that 
part  of  the  series  lying  in  composition  between  calcite  and  dolomite, 
while  all  those  more  uncommon  phases  carrying  more  magnesium  car- 
bonate than  the  45.65  per  cent  of  dolomite  are  usually  described  simply 
as  more  or  less  impure  magnesites. 

Though  magnesia  is  often  described  as  an  "  impurity "  in  lime- 
stone, this  word,  as  can  be  seen  from  the  preceding  statements,  hardly 


LIMESTONES.  91 

I 

expresses  the  facts  in  the  case.  The  magnesium  carbonate  present, 
whatever  its  amount,  simply  serves  to  replace  an  equivalent  amount 
of  calcium  carbonate,  and  the  resulting  rock,  whether  littie  or  much 
magnesia  is  present,  is  still  a  pure  carbonate  rock.  With  the  impuri- 
ties to  be  discussed  in  later  paragraphs,  however,  this  is  not  the  case. 
Silica,  alumina,  iron,  sulphur,  alkalies,  etc.,  when  present  are  actual 
impurities,  not  merely  chemical  replacements  of  part  of  the  calcium 
carbonate. 

The  presence  of  silica,  alumina,  iron,  and  other  impurities. — If  a 
number  of  limestone  analyses  be  examined,  it  will  be  found  that  the 
principal  impurities  present  are  silica,  alumina,  iron  oxide,  sulphur,  and 
alkalies. 

Silica  when  present  in  a  marble  or  crystalline  limestone  is  usually 
combined  with  alumina,  iron,  lime,  or  magnesia,  and  occurs  therefore 
in  the  form  of  a  silicate  mineral.  In  an  ordinary  limestone  it  is  very 
often  present  as  masses  or  nodules  of  chert  or  flint,  or  else  combined 
with  alumina  as  clayey  matter.  In  the  softer  limestones,  such  as  the 
chalks  and  marls,  the  silica  may  be  present  as  grains  of  sand. 

Alumina  is  commonly  present  combined  with  silica  either  as  grains 
of  a  silicate  mineral  or  as  clayey  matter. 

Iron  may  be  present  as  carbonate,  as  oxide,  or  in  the  sulphide  form 
as  the  mineral  pyrite. 

Sulphur  is  commonly  present  in  small  percentages  in  one  of  two 
forms:  as  pyrite  or  iron  disulphide  (FeS2)  or  as  gypsum  or  lime  sul- 
phate (CaS04  +  2H2O). 

The  alkalies  soda  and  potash  are  frequently  present  in  small  quan- 
tity, probably  in  the  form  of  carbonates. 

Geologic  and  geographic  distribution  of  limestones. — Limestones 
occur  in  every  state  and  territory  in  the  United  States,  though  of  course 
some  states  (Delaware,  North  Dakota,  Louisiana,  etc.)  are  so  poorly 
supplied  that  they  can  never  become  important  lime  producers,  while 
other  states  are  almost  entirely  underlain  by  limestone  strata.  Geo- 
logically, the  limestone  utilized  in  various  parts  of  the  United  States 
ranges  entirely  through  the  geological  column,  from  the  pre-Cambrian 
to  the  Pleistocene,  inclusive. 

Under  such  conditions  of  wide  geographic  and  geologic  distribu- 
tion it  is  not  practicable  to  give  a  summary  of  any  value  in  the  present 
volume.  The  list  of  references  given  in  the  following  pages  will  enable 
the  reader  to  ascertain  the  facts  regarding  the  limestones  of  any  given 
state  in  which  he  may  be  interested. 


92 


CEMENTS,  LIMES,  AND   PLASTERS. 


Reference  list  for  limestones. 
ALABAMA.  McCalley,  H.     The  fluxing  rocks  of  Alabama.     Eng.  and 

Min.  Journal,  vol.  63,  pp.  115,.  116.     1897. 
Meissner,  C.  A.     Analyses  of  limestones  and  dolomites  of 

the  Birmingham  district.     Proc.  Alabama  Industrial  and 

Scientific  Society,  vol.  4,  pp.  12-23.     1894. 
CALIFORNIA.  Jackson,  A.  W.     Building-stones  of  California.     7th  Annual 

Report  California  State  Mineralogist,  pp.  206-217.     1888. 
COLORADO.  Lakes,  A.     Building  and  monumental  stones  of  Colorado. 

Mines  and  Minerals,  vol.  22,  pp.  29-30.     1901. 
Lakes,  A.     Sedimentary  building-stones  of  Colorado.    Mines 

and  Minerals,  vol.  22,  pp.  62-64.  ''1901. 
CONNECTICUT.        Ries,   H.     The  limestone   quarries  of  eastern  New  York, 

western    Vermont,    Massachusetts,     and     Connecticut. 

17th  Ann.  Report  U.  S.  Geological  Survey,  pt.  3,  pp 

795-811.     1896. 
GEORGIA.  McCallie,  S.  W.     A  preliminary  report  on  the  marbles  of 

Georgia.     Bulletin   No.    1,   Georgia   Geological   Survey, 

92  pp.     1894. 
INDIANA,  Foerste,  A.  F.     A  report  on  the  Niagara  limestone  quarries 

of  Decatur,  Franklin,  and  Fayette  Counties.     22d  Ann. 

Rep.    Indiana   Dept.    Geology  and   Natural   Resources, 

pp.  195-255.     1898. 
Hopkins,  T.  C.,  and  Siebenthal,  C.  E.     The  Bedford  oolitic 

limestone  of  Indiana.     21st  Ann.   Rep.   Indiana  Dept. 

Geology  and  Natural  Resources,  pp.  291-427.     1897. 
IOWA.  Bain,  H.  F.     Properties  and  tests  of  Iowa  building-stones. 

Vol.  8,  Reports  Iowa  Geological  Survey,  pp.  367-416. 

1898. 
Houser   G.  L.     Some  lime-burning  dolomites  and  dolomitic 

building-stones    from    the    Niagara    of    Iowa.     Vol.    1, 

Reports  Iowa  Geological  Survey,  pp.  199-207.     1892. 
KANSAS.  Bailey,  E.  H.  S.,  and  Case,  E.  C.     On  the  composition  of 

some  Kansas  building-stones.     Trans.  Kansas  Academy 

Science,  vol.  13,  p.  78. 
KENTUCKY.  Crump,  H.  M.     The  clays  and  building-stones  of  Kentucky. 

Eng.  and  Mining  Journal,  vol.  66,  pp.  190-191.     Aug.  13, 

1898. 
MARYLAND.  An  account  of  the  character  and  distribution  of  Maryland 

building-stones,  together  with  a  history  of  the  quarrying 

industry.     Vol.  2,  Reports  Maryland  Geological  Survey, 

pp.  125-241.     1898. 
MASSACHUSETTS.    Ries,   H.    The  limestone  quarries  of  eastern  New  York, 

western     Vermont,     Massachusetts,     and     Connecticut. 

17th  Ann.  Rep.  U.  S.  Geol.  Survey,  pt  3,  pp.  795-811.  1896. 


LIMESTONES. 


MICHIGAN. 


MINNESOTA. 

MISSOURI. 

NEBRASKA. 

NEW  JERSEY. 
NEW  YORK. 


Benedict,  A.   C.    The   Bayport   (Mich.)   quarries.      Stone, 

vol.  17,  pp.  153-164.     1898. 
Grabau,   A.   W.      Stratigraphy  of  the   Traverse   group   of 

Michigan.     Ann.  Report  Michigan  Geological  Survey  for 

1901,  pp.  161-210.     1902. 
Lane,  A.  C.     Michigan  limestones  and  their  uses.     Eng.  and 

Mining  Journal,  vol.  71,  pp.  662-663,  693-694,  725.     1901. 
Lane,  A.  C.  -  Limestones  (of  Michigan).     Ann.  Rep.  Mich. 

Geol.  Survey  for  1901,  pp.  139-160.     1902. 
Lane,   A.   C.     Limestone    (of  Michigan).     Ann.  Rep.  Mich. 

Geol.  Survey  for  1902,  pp.  17  19.     1903. 
Winchell,  N.  H.     The  building-stones  of  Minnesota.    Vol.  1,. 

Final  Report  Geology  of  Minnesota,  pp.  142-204.     1884. 
Buckley,  E.  R.     Quarry  industry  of  Missouri.     Bulletin  2r 

Missouri  Geological  Survey,  1904. 
Fisher,  C.  A.   Directory  of  the  limestone  quarries  of  Nebraska. 

Ann.    Rep.   for    1901,    Nebraska   State   Board  of  Agri- 
culture, pp.  243-247.     1902. 
Cook,  G.  H.,  and  Smock,  J.  C.     New  Jersey  building-stones.. 

Vol.  10,  Reports  10th  Census,  pp.  139-146.     1884. 
Nason,   F.   L.     The   chemical   composition  of  some  of  the 

white  limestones  of  Sussex  County,  New  Jersey.     Ameri- 
can Geologist,  vol.  13,  pp.  154-164.     1894. 
Bishop,   I.   P.     Structural   and   economic   geology  of  Erie 

County,  N.  Y.     15th  Ann.  Rep.  N.  Y.  State  Geologist,. 

vol   1,  pp.  305-392.     1897. 
Eckel,   E.   C.     The   quarry   industry  in  southeastern  New 

York.     20th  Ann.  Rep.  N.  Y.  State  Geologist,  pp.  141- 

176      1902. 
Lincoln,   D.    F.     Report   on   the   structural   and   economic 

geology  of  Seneca  County,  N.  Y.     14th  Ann.  Rep.  New 

York  State  Geologist,  pp.  60-125.     1897. 
Hies,   H      The   limestone    quarries   of   eastern  New  York, 

western     Vermont,     Massachusetts,     and     Connecticut. 

17th  Ann.  Rep.  U.  S.  Geological  Survey,  pt.  3,  pp.  795- 

811.     1896. 
Hies,  H.     Limestones  of  New  York  and  their  economic  uses. 

17th  Ann.   Rep.   N.   Y.   State   Geologist,   pp.   355-468. 

1899. 

Ries,  H.     Lime  and  cement  industries  of  New  York.     Bul- 
letin 44,  N.  Y.  State  Museum.     1903. 
Smock,  J.  C.     Building-stones  in  the  state  of  New  York. 

Bulletin  3,  N.  Y.  State  Museum,  152  pp.     1888. 
Smock,  J    C.     Building-stone  in  New  York.      Bulletin  10,, 

N.  Y.  State  Museum,  396  pp.     1890. 


94 


CEMENTS,  LIMES,  AND  PLASTERS. 


OKLAHOMA.  Gould,    C.     N.     Oklahoma    limestones.     Stone,    vol.    23. 

pp.  351-354.     1901. 

PENNSYLVANIA.      Frear,  W.     The  use  of  lime  on  Pennsylvania  soils.     Bulle- 
tin 61,  Penna.  Dept.  Agriculture,  170  pp.     1900. 

SOUTH  DAKOTA.     Todd,  J.  E.     The  clay  and  stone  resources  of  South  Dakota, 
Eng.  and  Mining  Journal,  vol.  66,  p.  371.     1898. 

TENNESSEE.  Cotton,    H.    E.,    and    Gattinger,    A.     Tennessee    building- 

stones.   -Vol.   10,  Jeports  Tenth  Census,  pp.  187,  188. 
1884. 

Keith,  H.     Tennessee  marble.      Bulletin  213,  U.  S.  Geol. 
Survey,  pp.  366-370.     1903. 

TEXAS.  Dumble,  E.  T.     Building  and  ornamental  stones  of  Texas. 

Stone,  May,  1900. 

VERMONT.  Perkins,  G.  H.     Report  on  the  marble,  slate,  and  granite 

industries  of  Vermont.     68  pp.     Rutland,  1898. 
Perkins,  G.  H.     Limestone  and  marble  in  Vermont.     Rep. 
Vermont  State  Geologist  for  1899-1900,  pp.  30-57.    1900. 
Ries,   H.     The   limestone   quarries   of   eastern   New  York, 
western    Vermont,     Massachusetts,     and     Connecticut. 
17th  Ann.  Rep.  U.  S.  Geol.  Survey,  pt.  3,  pp.  795-811. 
1896. 

WISCONSIN.  Buckley,  E.  R.     Building  and  ornamental  stones  of  Wiscon- 

sin.    Bulletin  4,  Wisconsin  Geol.  Survey,  500  pp.     1898. 

WYOMING.  Knight,  W.  C.     The  building-stones  and  clays  of  Wyoming. 

Eng.  and  Mining  Journal,  vol.  66,  pp.  546-547.     1898. 

Shells  as  sources  of  lime.* — Most  molluscan  shells  consist  essen- 
tially of  lime  carbonate,  with  commonly  very  small  percentages  (less 
than  1  per  cent)  of  magnesium  carbonate,  and  traces  of  alkalies, 
phosphoric  acid,  etc.  The  analyses  given  in  Table  31  will  serve  to 
illustrate  the  composition  of  the  shells  of  three  common  species  of 
molluscs. 

These  analyses  show  that  in  ordinary  practice  an  oyster-shell  may 
be  expected  to  contain,  as  its  principal  impurities,  several  per  cent 
of  organic  matter  and  from  a  trace  to  5  per  cent  of  silica,  iron  oxide, 
and  alumina.  The  amount  of  these  last  clayey  impurities  present  will 
doubtless  vary  with  the  cleanness  of  the  shell,  as  it  is  probable  that 
they  are  in  large  part  purely  external  impurities. 

*  Brown,  L.  P.,  and  Koiner,  J.  S.  H.  Analysis  of  oyster-shells  and  oyster-shell 
lime.  American  Chemical  Journal,  vol.  11,  pp.  36-37.  1889. 

How,  Dr.  On  the  comparative  composition  of  some  recent  shells,  a  Silurian 
fossil  shell,  and  a  Carboniferous  shell  limestone.  American  Journal  of  Science 
2d  series,  vol.  41,  pp.  379-384.  1866. 


LIMESTONES. 


95 


TABLE  31. 
ANALYSES  OF  VARIOUS  MOLLUSCAN  SHELLS. 


1. 

2. 

3. 

4. 

5. 

6. 

Silica  (SiO2)  

3.30 
0.08 
0.17 
52.14 
0.25 
0.35 
0.16 
n.  d. 
41.61 

2.32 

1.49 

0.04 
53.37 

0.81 
0.11 
40.60 

3.48 

n.  d. 

n.  d. 
n.  d. 

o:so 

n.  d. 
n.  d. 

3.17 

0.20 

0.04 
52.86 

0.35 
0.05 
41.02 

5.02 

0.16 
54.55 

0.28 
0.001 

42.82 

2.01 

n.d. 
54.38 

0.28 
n.  d. 
n.  d. 

2.04 

Alumina  (A12O3)  

Iron  oxide  (f'e2O3)  

Lime  (CaO)  

Magnesia  (MgO)  

Alkalies  (K2O,Na2O) 

Sulphur  trioxide  (SO3)  

Phosphorus  pentoxide  (P2O6).  .  . 
Carbon  dioxide  (CO2) 

Water  

Organic  matter  

1.  Oyster-shell.  L.  P.  Brown  and  J.  S.  H.  Koiner,  analysts.  Amer.  Chemical  Journal,  vol.  11, 
pp.  36-37. 

2-3.  Oyster-shell.      How,  analyst.     Amer.  Journal  of  Science,  2d  series,  vol.  41,  p.  380 

4.  Mussel-shell.  "  "         "       "          "        "         "     "        " 

5-6    Periwinkle-shell.   "  "  "         "       "          "        "         "     "    p.  379-381. 

At  various  points  where  the  oyster-canning  industry  is  largely 
developed  oyster-shells  are  burned  into  lime.  An  important  lime- 
burning  industry  is,  for  example,  based  upon  the  use  of  waste  oyster- 
shells  at  Baltimore,  Md.  In  the  case  of  the  lime  whose  analysis  is 
given  below  the  shells  had  been  charged,  mixed  with  small  anthracite, 
into  a  cylindrical  kiln,  and  the  resulting  lime  consequently  shows  the 
presence  of  a  considerable  amount  of  coal-ash.  By  burning  the  shells 
in  kilns  with  separate  furnaces  this  can  be  avoided,  giving  a  much  Im- 
proved product. 

The  following  analyses  were  made  *  by  L.  P.  Brown  and  J.  S.  H.  Koiner 
on  the  oyster-shell  used  in  lime-burning  at  Baltimore,  Md.,  and  the 
resulting  lime. 

TABLE  32. 
ANALYSES  OF  OYSTER-SHELLS  AND  OYSTER-SHELL  LIME. 


Shell. 

Lime. 

Silica  (SiO2)            

3.30 

6.29 

Alumina  (A12O3)  

0.08 
0.17 

0.42 
0.33 

Lime  (CaO)           

52.14 

85.49 

Magnesia  (MffO)                 

0.25 

0.31 

Alkalies  (K  O  Na  6)        

0.35 

0.80 

Sulphur  trioxide  (SO3)   

0.16 

0.66 

Carbon  dioxide  (CO2)   

41.61 

0.70 

Water                       

3.97 

2.32 

*  American  Chemical  Journal,  vol.  11,  p.  37,  1889. 


CHAPTER  VII. 

'  •          ?* 
LIME-BURNING. 

BEFORE  taking  up  the  discussion  of  manufacturing  methods  it  will 
be  of  value  to  consider  briefly  the  chemical  principles  upon  which  these 
methods  are  based  and  the  classes  of  products  which  result. 

The  burning  of  a  pure  non-magnesian  limestone. — An  absolutely  pure 
limestone,  free  from  both  magnesia  and  other  impurities,  corresponds 
in  composition  to  calcium  carbonate  (CaCOs).  If  a  pure  limestone 
be  heated  to  800°  C.  or  over,  this  carbonate  is  dissociated,  the  carbon 
dioxide  (CO2)  being  driven  off  as  a  gas,  while  the  calcium  oxide  (CaO) 
is  left  behind  as  a  white  solid,  known  as  quicklime  or  caustic  lime.  This 
decarbonation  may  be  expressed  in  a  formula  as  follows: 

Limestone  (CaCOs)  +  heat  =  CaO  (lime)  +  CO  2  (carbon  dioxide). 

As  the  original  lime  carbonate  consisted  of  56  parts  by  weight  of 
CaQ  to  44  parts  of  CO2,  the  formula  may  be  given  a  commercial  quanti- 
tative value,  as  below: 

100  Ibs.  limestone  +  heat  =  56  Ibs.  quicklime +  44  Ibs.  carbon  dioxide. 

In  the  process  of  burning  from  limestone  to  quicklime,  the  material 
has  therefore  lost  44  per  cent  in  weight.  It  has  also  decreased  in  bulk, 
but  in  a  much  smaller  ratio,  the  decrease  varying  from  12  to  20  per  cent. 
Pure  limestone  has  a  specific  gravity  of  2.715,  while  the  true  specific 
gravity  of  pure  quicklime  is  3.09  to  3.15,  though  much  less  in  lumps. 

The  dissociation  of  limestone  on  heating  begins  at  a  temperature 
of  about  750°  C.,  but  is  usually  not  complete  until  900°  C.  or  there- 
abouts is  reached.  As  the  expulsion  of  the  carbon  dioxide  is  hindered 
by  the  presence  of  the  gas  itself  dissociation  is  accomplished  more  rapidly 
if  either  (a)  the  carbon-dioxide  gas,  as  fast  as  it  is  formed,  is. removed 
from  the  kiln  by  a  pump,  or  (6)  a  jet  of  steam  or  water  is  introduced, 
the  effect  being  to  form  a  mixture  of  steam  and  carbon  dioxide,  which 
exerts  less  pressure  than  would  the  pure  gas  alone.  In  practice  the 
pumping  method  is  rarely  used,  but  the  injection  of  water  or  steam 
is  quite  a  common  practice. 

96 


LIME-BURNING.  97 

The  burning  of  a  magnesian  limestone.  —  If  the  limestone,  though 
otherwise  pure,  contains  magnesium  carbonate,  the  effects  produced 
by  burning  will  vary  somewhat  from  those  discussed  above.  Suppose, 
for  example,  that  'a  limestone  consisting  of  60  per  cent  lime  carbonate 
+40  per  cent  magnesium  carbonate  be  burned  until  dissociated.  The 
original  limestone  consisted  of 

60  Ibs.  CaC03(  =  CaO  +  CO2)+40  Ibs.  MgCO3(MgO  +  C02). 

While  lime  carbonate  is  made  up  of  56  per  cent  CaO  plus  44  per  cent 
CC>2,  magnesium  carbonate  contains  47.6  per  cent  MgO  plus  52.4  per 
cent  CO2-  The  bulk  composition  of  the  original  limestone  may, 
therefore,  be  expressed  quantitatively  as  follows: 

60  Ibs.  lime  carbonate-  ..............  "  {aMO  ^  CO? 


40    "    magnesium  carbonate  =  ..  ..™'™ 

1     £\J  .  V/O 

The  original  rock,  therefore,  carries  in  100  Ibs.  33.60  Ibs.  of  lime  (CaO), 
19.04  Ibs.  of  magnesia  (MgO),  and  47.36  Ibs.  of  carbon  dioxide  (C02). 

If  a  rock  of  this  composition  be  burned,  the  carbon  dioxide  will  be 
driven  off,  as  in  the  case  of  a  pure  limestone,  but  the  solid  mass  remain- 
ing will  consist  partly  of  lime  (CaO)  and  partly  of  magnesia  (MgO). 
In  addition  to  this  difference,  a  difference  in  loss  of  weight  is  to  be  noted. 
In  discussing  the  burning  of  a  pure  non-magnesian  limestone  it  was 
stated  that  the  driving  off  of  the  carbon  dioxide  meant  the  loss  of  44 
per  cent  in  weight.  In  the  case  of  the  particular  magnesian  limestone 
here  discussed  it  can  be  seen  that  the  expulsion  of  the  carbon  dioxide 
is  equivalent  to  a  loss  of  47.36  per  cent  in  weight. 

Dissociation,  in  the  case  of  a  magnesian  limestone,  appears  to  be 
effected  at  a  somewhat  lower  temperature  *  than  when  a  non-mag- 
nesian limestone  is  burned,  but  no  accurate  data  on  this  point  are  avail- 
able. 

Classification  of  limes.  —  For  commercial  purposes  limes  carrying  less 
than  5  per  cent  of  magnesia  can  be  marketed  as  pure  or  high-calcium 
limes;  but  those  containing  over  5  per  cent  differ  so  markedly  in  their 
properties  that  it  is  necessary  to  class  them  separately.  The  groups 
are,  therefore,  as  follows: 

GROUP  A.  High-calcium  limes:  Limes  containing  less  than  5  per  cent  of 
magnesia.  The  limes  of  this  group  differ  among  themselves  according 
to  the  amount  of  silica,  alumina,  iron,  etc.,  contained.  A  lime  carrying 
less  than  5  per  cent  of  such  impurities  is  a  "fat"  or  "rich"  lime,  as 
distinguished  from  the  more  impure  "lean"  or  "poor"  limes. 

*  Probably  about  600°-700°  C. 


98  CEMENTS,  LIMES,  AND  PLASTERS. 

GROUP  B.  Magnesian  limes:  Limes  containing  over  5  per  cent  (usually  30 
per  cent  or  over)  of  magnesia.  These  limes  are  all  slower  slaking  and 
cooler  than  the  high-calcium  limes  of  the  preceding  group,  and  they 
appear  to  make  a  stronger  mortar.  They  are,  however,  less  plastic 
or  "smooth",  and  in  consequence  are  disliked  by  workmen.  As  com- 
mercially produced,  they  usually  carry  over  30  per  cent  of  magnesia. 


Methods  and  Costs  of  Lime-burning. 

». 

Compared  with  the  complicated  processes  employed  in  the  manu- 
facture of  Portland  cement,  lime-making  is  a  very  simple  industry, 
the  only  distinctive  operation  requiring  attention  being  the  burning 
of  the  limestone.  In  the  present  section  the  types  of  lime-kilns  employed 
at  various  localities  will  be  considered,  detailed  descriptions  of  several 
of  the  more  important  styles  being  given.  A  few  brief  notes  on  the 
utilization  of  a  hitherto  practically  unused  by-product  (carbon  dioxide) 
will  then  be  given,  after  which  the  costs  of  lime-manufacture  will  be 
considered. 

Heat  requirements  in  lime-burning. — In  burning  limestone  to  lim- 
heat  is  required  for  three  purposes: 

(a)  Evaporating  any  water  contained  in  the  limestone. 
(6)  Heating  the  limestone  to  its  dissociation  temperature, 
(c)  Driving  off  carbon  dioxide  from  the  lime  (and  magnesium) 
carbonate. 

The  water  in  the  limestone,  however,  aids  in  the  dissociation,  so 
that  the  first  heat  requirement  may  be  neglected  here.  Heating  the 
limestone  from  the  air  temperature  (say  60°  F.)  to  its  point  of  disso- 
ciation (about  1300°  F.  for  non-magnesian  limestones),  assuming  that 
within  this  range  the  specific  heat  of  limestone  is  0.22,  would  require, 
for  one  ton  of  limestone  2000  X 0.22  X  (1300 -60)  =  545,600  B.T.U.  For 
a  magnesian  limestone,  which  loses  its  carbon  dioxide  at  a  lower  tem- 
perature, this  amount  would  be  considerably  reduced. 

The  heat  used  in  the  actual  dissociation  is  known  quite  accurately. 
One  pound  of  lime  carbonate  (CaCO3)  will  require  784  B.T.U.  for  its 
dissociation,  while  one  pound  of  magnesium  carbonate  would  require 
only  381  B.T.U.  Using,  then,  these  data  in  connection  with  those 
quoted  in  the  preceding  paragraph,  the  following  tabulated  statement 
can  be  made  concerning  the  total  heat  requirements  in  burning  lime- 
stones of  different  composition.  In  actual  practice,  of  course,  the  fuel 
consumption  is  always  far  in  excess  of  these  theoretical  requirements. 


LIME-BURNING. 


99 


TABLE  33. 

HEAT  AND  FUEL  THEORETICALLY  REQUIRED  IN  BURNING  ONE  TON  OP 

LIMESTONE. 


Composition  of  Limestone. 

100%  CaC03. 

80%  CaCO3, 
20%  MgCO3. 

50%  CaCOs, 
50%  MgCO3. 

Heat  required  for  heating  to 
dissociation-point     

545,600  B.T.U. 
1,568,000        " 

457,600  B.T.U. 
1,406,800        " 

369,600  B.T.U. 
1,165,000       " 

Heat  required  for  actual  dis- 
sociation   

Total  heat  requirements  .... 

Coal     theoretically     required 
(14,000  B.T.U.  per  lb.): 
Intermittent  kilns 

2,113,600  B.T.U. 

151  Ibs. 
112  Ibs. 

1,864,400  B.T.U. 

133  Ibs. 
101  Ibs. 

1,534,600  B.T.U. 

110  Ibs. 
76  Ibs. 

Continuous  kilns  . 

The  above  results  are  to  be  regarded  only  as  approximations  to 
the  truth,  because  the  chemical  data  on  which,  the  calculations  are 
based  are  not  accurately  determined,  but  the  figures  suffice  to  show 
the  great  economy  in  fuel  consumption  which  comes  from  the  use  of 
highly  magnesian  limestone. 

Types  of  lime-kilns. — The  types  of  kilns  employed  in  lime-burning 
may  be  grouped  as  follows: 


Intermittent  kilns 
Continuous  kilns 

xr      '    ,  ,  .,         .      .  .     ,        C  limestone  and  fuel  fed  ) 
Vertical  kiln,  mixed  leed. .  .  •{      .      ,,  ,  V 

(      in  alternate  layers     ) 

Vertical  kiln,  separate  feed .  . .  limestone  and  fuel  not  in  contact  (3) 
Ring  or  chamber  kiln (4) 


(1) 

(2) 


(1)  Intermittent  kilns  are  those  in  which  each  burning  of  a  charge 
constitutes  a  separate  operation.  The  kiln  is  charged,  burned,  cooled, 
and  the  charge  is  drawn;  then  the  kiln  is  again  charged,  and  so  on. 
The  disadvantages  of  this  intermittent  mode  of  operation  are  obvious; 
and  kilns  of  this  type  are  consequently  employed  only  where  there  is  a 
slight  or  very  irregular  demand  for  the  product.  Old  kilns  of  this  kind 
can  still  be  seen  in  farming  regions,  where  charges  of  lime  are  burned 
as  the  neighborhood  demand  requires. 

These  primitive  kilns  were  *  "  rudely  constructed  of  stone,  and 
were  located  on  the  side  of  a  hill,  so  that  the  top  was  easily  accessible 


*  Blatchley,  S.  W.      29th  Ann.  Rep.  Indiana  Dept.  Geology,  pp.  225-227,  1904 


100  CEMENTS,  LIMES,  AND  PLASTERS. 

for  charging  the  kiln  with  stone  and  the  bottom  for  supplying  fuel 
and  drawing  out  the  lime.  In  charging,  the  largest  pieces  of  limestone 
were  first  selected  and  formed  into  a  rough  dome-like  arch  with  large 
open  joints  springing  from  the  bottom  of  the  kiln  to  a  height  of  five 
or  six  feet.  Above  this  arch  the  kiln  was  filled  from  the  top  with  frag- 
ments of  limestone,  the  larger  pieces  being  used  in  the  lower  layers, 
these  being  topped  off  with  fragments  of  smaller  size.  A  wood  fire 
was  then  started  under  the  dome,  the  heat  being  raised  gradually  to 
the  required  degree  in  order  to  prevent  the  sudden  expansion  and  con- 
sequent rupture  of  the  stones  forming  the  dome.  Should  this  happen, 
a  downfall  of  the  entire  overlying  mass  would  take'  place,  putting  out 
the  fire  and  causing  the  total  loss  of  the  contents  of  the  kiln.  After  a 
bright  heat  was  once  reached  throughout  the  mass  of  stone,  it  was 
maintained  for  three  or  four  days  to  the  end  of  the  burning.  This  was 
indicated  by  a  large  shrinkage  in  volume  of  the  contents  of  the  kiln, 
the  choking  up  of  the  spaces  between  the  fragments,  and  the  ease  with 
which  an  iron  rod  could  be  forced  down  from  the  top.  The  fire  was  then 
allowed  to  die  out  and  the  lime  was  gradually  removed  from  the  bottom. 
It  was  in  this  manner  that  all  the  lime  used  in  Indiana  for  many  years 
was  burned,  and  in  some  localities  these  temporary  intermittent  kilns 
are  still  in  operation.  The  process  of-  burning  is  simple  and  cheap, 
the  only  expense  being  for  blasting  the  stone  and  preparing  the  fuel. 
Possibly  but  one  or  two  kilns  were  necessary  to  supply  a  neighbor- 
hood for  a  year.  These  were  operated  for  a  week  or  two  when  required 
and  remained  idle  for  the  remainder  of  the  year. 

"As  the  population  increased,  the  demand  for  lime  became  greater, 
and  in  many  places  permanent  kilns  lined  with  fire-brick  were  erected. 
These  were  the  old-fashioned  stone  '  pot-kilns '  of  a  quarter  century  ago. 
On  the  inside  they  were  usually  circular  in  horizontal  section,  tapering 
slightly,  by  a  curve  both  up  and  down,  from  the  circle  of  largest  diameter, 
which  was  from  4  to  6  feet  above  the  bottom.  A  kiln  10  to  11  feet 
in  greatest  diameter  was  25  to  28  feet  high,  5  to  6  feet  in  diameter  at 
the  top  and  7  to  8  feet  at  the  bottom.  There  was  an  arched  opening 
on  one  side  at  the  bottom  5  or  6  feet  high,  through  which  the  wood 
was  introduced  and  the  burnt  lime  removed.  A  horizontal 'grating 
on  which  the  fire  was  built  was  usually  placed  1  or  2  feet  above  the 
bottom. 

"In  all  these  intermittent  kilns  there  was  an  enormous  loss  of  heat 
at  each  burning,  for  the  quantity  of  fuel  necessary  to  raise  the  contents 
of  the  kiln  and  the  thick  stone  and  brick  walls  to  the  necessary  degree 
of  heat  had  to  be  repeated  each  time  the  kiln  was  charged.  Moreover, 


LIME-BURNING.  IQl 

the  stone  nearest  the  dome  arch  in  the  kiln  was  liable  to  become  in- 
jured by  overburning  before  the  top  portions  of  the  charge  where  tor- 
oughly  calcined." 

(2)  Vertical  kilns  with  mixed  feed. — In  kilns  of  this  type  the  lime- 
stone and  fuel  are  charged  into  the  kiln  in  alternate  layers.  As  the 
burning  progresses  burned  lime  is  drawn  from  the  bottom  of  the  kiln, 
while  fresh  layers  of  limestone  and  fuel  are  added  at  the  top. 

The  advantages  of  mixed-feed  kilns,  as  compared  with  the  separate 
feed-kilns  described  below,  are  (a)  that  they  are  cheaper  to  construct, 
(b)  that  they  are  somewhat  more  economical  of  fuel,  and  (c)  that  they 
give  for  the  same  size  of  kiln  a  larger  output  in  the  same  time.  These 
advantages  are  partly  counterbalanced  by  the  disadvantages  to  which 
they  are  subject,  these  being  (a)  that  the  burned  lime  is  discolored 
to  some  extent  by  its  contact  with  the  fuel,  (6)  that  the  ashes  of  the 
fuel  cannot  readily  be  separated  from  the  burned  lime,  thereby  lower- 
ing the  quality  of  the  product,  and  (c)  that  a  part  of  the  fuel  ashes 
may  clinker  on  the  outside  of  the  lumps  of  lime,  preventing  even  and 
satisfactory  burning. 

To  sum  up  the  advantages  and  disadvantages:  the  "mixed-feed" 
kiln  is  cheaper  both  in  first  cost  and  in  operating  expenses ;  its  product 
is  good  enough  for  most  ordinary  purposes,  but  is  not  as  evenly  burned 
or  as  white  as  is  the  product  of  a  "separate-feed"  kiln. 

At  a  small  Pennsylvania  lime-plant  three  vertical  mixed-feed  kilns 
are  in  use.  Each  of  these  kilns  takes  about  24  tons  of  stone  per  day, 
requiring  the  services  of  six  quarrymen  to  keep  the  three  kilns  supplied. 
Bituminous  slack  is  used  for  fuel,  the  consumption  being  26  Ibs.  slack 
per  bushel  (75  Ibs.)  of  lime,  equivalent  to  a  fuel  consumption  of  34.7  per 
cent  on  the  weight  of  lime  produced.  This  ratio  if  correct  is  enormous 
compared  to  natural-  or  even  Portland-cement  plants,  and  points  to 
unusually  inefficient  management.  As  a  general  rule,  a  vertical  mixed- 
feed  kiln  may  be  expected  to  produce  lime  with  a  fuel  consumption  of 
from  15  to  25  per  cent  of  the  weight  of  clean  product.  The  cause  of 
this  apparently  high  consumption  is  that  so  much  of  the  product  is 
usually  unfit  for  use. 

The  Aalborg  or  Schofer  kiln,  one  of  the  best  types  of  stationary 
kilns  for  cement  practice,  has  been  employed  in  a  somewhat  modified 
form  for  burning  lime  and  hydraulic  lime.  The  lime-kiln  of  this  type 
is  shown  in  Fig.  21.  The  limestone  is  fed  in  at  the  charging  door  B, 
while  the  fuel  is  charged  through  the  chutes  //.  The  mass  of  limestone 
in  the  preheating  chamber  D  is  dried,  heated,  and  partly  decarbonated 
before  it  enters  the  burning-zone,  when  the  decarbonation  is  complete. 


CEMENTS,  LIMES,  AND  PLASTERS. 

The    cooling-chamber  C  reduces  the  temperature    of  the  burned  lime 
and  incidentally  heats  the  air  which  passes  through  it  to  supply  com- 


bustion.      These  features  make   the  Aalborg  kiln  very  economical  in 
fuel  consumption.     Each  kiln  will  turn  out  15  to  20  tons  per  day,  and 


LIME-BURNING. 


103 


will  use  220  to  260  pounds  of  coal  per  ton  of  quicklime  burned,  equiva- 
lent to  a  fuel  consumption  of  10  to  12  per  cent  on  the  weight  of  the 
product,  which  is  very  close  to  the  theoretical  minimum. 

(3)  Vertical  kilns  with  separate  feed.— Kilns  of  this  type,  which  are 
now  used  at  most  of  the  larger  lime-burning  plants,  are  equipped  with 
separate  fireplaces  to  carry  the  fuel,  distinct  from  the  body  of  the  kiln. 


FIG.  21. — Aalborg  kiln  for  lime-burning. 

These  fireplaces  may  be  set  either  in  the  wall  of  the  kiln,  the  usual  posi- 
tion when  a  stone-walled  kiln  is  used,  or  outside  of  the  kiln-shell.  The 
kiln  body  proper  contains  the  charge  of  limestone,  while  the  fuel  is  fed 
and  burned  in  these  fireplaces  or  furnaces.  The  limestone,  therefore, 
does  not  come  into  direct  contact  with  the  fuel,  but  only  with  the  hot 
fuel  gases.  Other  things  being  equal,  kilns  of  this  type  could  not  show 
quite  as  high  a  fuel  efficiency  as  kilns  in  which  the  limestone  and  fuel 


104  CEMENTS,  LIMES,  AND  PLASTERS. 

are  charged  together  in  alternate  layers.  The  product,  however,  is 
of  a  much  higher  grade,  for  it  is  not  discolored  by  contact  with  the  fuel, 
and  it  contains  no  fragments  of  unburned  fuel  or  fuel  ashes  and  clinkers. 
With  average  care  in  feeding  and  burning,  it  is  probable  that  at  least 
90  per  cent  of  the  product  from  a  kiln  of  this  type  will  be  a  well-burned 
clean  white  lime,  as  compared  with  the  75  or  80  per  cent  obtainable 
from  mixed-feed  kilns.  As  the  fuel-burning  apparatus  is  entirely  dis- 
tinct from  the  body  of  the  kiln,  the:  firing  can  be  kept  under  better 
control,  so  that  the  percentage  of  underburned  and  overburned  material 
in  the  product  should  be  materially  decreased. 

Kilns  of  this  type  are  commonly  35  to  50  feet  in'  height  and  5  to  8 
feet  in  inside  diameter,  with  either  two  or  four  fireplaces  or  "furnaces". 

The  Keystone  kiln,  described  in  detail  below,  may  be  taken  as  fairly 
representative  of  this  type  of  lime-kiln. 

The  Keystone  kiln  is  built  on  BroomelPs  patent  by  the  Broomell, 
Schmidt  &  Steacy  Company,  of  York,  Pa.  Its  construction  can  be 
clearly  seen  from  Fig.  22,  which  shows  the  kiln  with  a  portion  of  the 
shell  cut  away  to  exhibit  the  interior,  and  with  the  side  wall  of  the  fur- 
nace removed  to  show  its  construction.  The  kiln  from  top  to  floor 
is  a  heavy  steel  shell,  lined  with  fire-brick.  The  base  of  the  kiln  below 
the  firing  platform  is  made  from  very  heavy  steel  plates,  reinforced 
on  the  inside  by  numerous  stiffening-ribs.  The  furnaces  are  carried 
on  steel  platforms  which  extend  a  sufficient  distance  in  front  of  the 
firing-doors  to  give  a  convenient  working  space.  In  addition  to  being 
supported  at  the  inner  ends  by  attachment  to  the  shell  of  the  kiln 
the  steel  beams  which  floor  the  platforms  rest  at  their  outer  ends  on 
steel  columns. 

In  operating  this  kiln  the  flame  from  the  coal  (or  wood)  burned 
in  each  furnace  is  directed  through  two'  large  openings  in  the  kiln  shell 
and  lining  directly  against  the  limestone  which  fills  the  kiln.  These 
openings,  as  well  as  the  kiln  shell  and  the  furnaces,  are  lined  with  fire- 
brick. 

As  the  lime  passes  the  burning-zone  it  falls  into  a  "  cooling -cone  " 
made  of  steel  plates.  This  is  an  inverted  hollow  frustum  of  a  cone 
suspended  from  a  heavy  cast-iron  plate,  which  in  turn  is  supported 
by  gusset  plates  riveted  to  the  base  of  the  kiln.  The  cooling-cone  varies 
from  6  to  6£  feet  in  diameter  at  top,  according  to  the  size  of  the  kiln, 
and  is  7  feet  high.  The  burned  and  partly  cooled  lime  is  drawn  from 
the  cone  by  means  of  shears  or  draw-gates  at  its  bottom.  These  gates 
are  operated  by  hand- wheels  which  project  outside  of  the  kiln  base, 
thus  removing  the  operator  from  the  dust  and  heat  of  the  lime.  The 


LIME-BURNING. 


105 


FIG.  22.— Keystone  lime-kiln. 


106 


CEMENTS,  LIMES,  AND  PLASTERS. 


lime  can  be  discharged  into  a  car  run  in  under  the  cooling-cone  or  on 
the  floor.  The  heated  air  which  ordinarily  would  accumulate  around 
the  cooling-cone  is  discharged  into  the  ash-pit  under  the  grates,  which 
adds  considerably  to  the  efficiency  of  the  furnace.  Arrangement  can 
also  be  made  for  placing  a  steam-jet  in  the  hot-air  passage  so  as  to  pro- 
vide forced  draft  if  desired. 

v    TABLE  34. 
DIMENSIONS  OF  KEYSTONE  LIME-KILNS. 


No.  l. 

No.  2. 

No.  3. 

Outside  diameter  of  shell 

10  ft 

ll-i    ft 

12  ft 

Inside  diameter  of  lining 

5    " 

6      " 

6*" 

Total  height      

38    " 

43      " 

48    " 

Output  per  day,  in  bushels  of  70  Ibs      .  .  . 

200-250 

250-300 

300-350 

Many  patents  have  been  taken  out  to  cover  improvements  in  various 
details  of  the  ordinary  lime-kiln.  One  of  these  patented  devices  is 
shown  in  Fig.  23,  where  boilers  are  inserted  in  the  kiln  arches  so  as  to 
utilize  the  waste  heat  of  the  kiln.  The  boilers,  in  turn,  are  used  to 
develop  the  power  needed  for  running  drills,  hoists,  and  other  machinery 
in  the  quarry  and  mill. 

(4)  Ring  or  chamber  fains. — Chamber  kilns  of  the  Hoffman  type, 
though  never  used  in  America,  are  in  somewhat  extensive  use  in  Europe 
for  both  lime  and  Portland-cement  burning.  They  are  described 
briefly  on  pages  in  connection  with  the  burning  of  Portland  cement. 
When  used  for  burning  lime  in  Europe,  a  fuel  consumption  of  400  to 
450  Ibs.  coal  per  ton  (2000  Ibs.)  of  burned  lime  is  attained  in  common 
practice,  while  lower  consumption  can  be  expected  under  favorable 
conditions.  The  Hoffman  kiln  is,  of  course,  a  great  improvement  in 
both  economy  and  quality  of  product  on  the  old  style  of  vertical  kiln, 
but  it  is  doubtful  if  it  gives  better  results  than  the  modern  kilns  now 
in  use  in  the  more  important  American  lime-plants. 

Gen.  Q.  A.  Gillmore  stated  *  in  1871  that  a  Hoffman  kiln  used  for 
lime-burning  at  Llandulas,  Wales,  produced  about  80  tons  of  lime  per 
day  at  the  following  detailed  cost: 

Cost  of  quarrying  stone,  including  tools $0 . 31  ^ 

Charging  kiln 0 .  lo| 

Drawing  kiln 0  07£ 

Wages  of  burners \\  0  Q71 

Fuel  at  SI . 75  per  ton '.'.'.'.'.  Q. 37* 

Managing  expenses,  etc .'.'.'  0.31} 

Cost  of  lime  per  ton $1 . 25 

*  Gillmore,  Q.  A.  A  practical  treatise  on  Coignet-Beton  and  other  artificial 
stone,  pp.  71-72,  1871. 


LIME-BURNING. 


107 


LJ  t     I    f    )    I    I    l    l    < 


_LJ_L_      /    f     t     1    I    1    I    (    i    I 


FIG.  23. — O'Connell  lime-kiln. 


108  CEMENTS,  LIMES,  AND  PLASTERS. 

He  further  estimated  that  at  the  current  prices  (1871)  of  labor 
and  fuel  in  the  United  States,  lime  could  be  manufactured  in  a  Hoff- 
man kiln  at  about  $2  per  ton,  the  following  details  of  cost  being 
given : 

Cost  of  quarry  and  plant \   $20,000 

Annual  yield  of  kiln,  tons 20,000 

Per  Ton  Lime. 

Interest  on  investment ?. $0 .07 

Quarrying  stone 0 . 65 

Charging  kiln 0 .20 

Drawing  kiln 0.15 

Wages  of  burners 0.15 

Fuel 0 . 43 

Contingent  expenses,  20  per  cent 0 . 33 

$1.98 

Utilization  of  carbonic-acid  gas  from  lime-kilns. — During  the  burn- 
ing of  limestone  to  lime  an  enormous  amount  of  carbonic-acid  gas 
(carbon  dioxide,  €62)  is  driven  off  and  usually  wasted.  The  extent  of 
this  waste  may  be  appreciated  when  it  is  recalled  that  100  Ibs.  of  pure 
limestone  would  give  on  calcination  56  Ibs.  of  quicklime  and  44  Ibs. 
of  carbon  dioxide.  To  put  the  matter  in  another  way,  for  every  ton 
(2000  Ibs.)  of  lime  made  1571  Ibs.  of  carbon  dioxide  are  thrown  into 
the  atmosphere.  During  the  year  1903,  therefore,  over  one  and  a 
half  million  tons  of  carbon  dioxide  were  produced — and  wasted — from 
the  lime-works  of  the  United  States.  Few  attempts  have  been  made 
by  lime-manufacturers  to  utilize  this  valuable  by-product,  though  the 
manufacture  of  carbonic  acid,  as.  an  independent  industry,  has  become 
of  great  importance. 

Mr.  Henry  A.  Mather  states  *  that  carbon  dioxide  from  lime-kilns 
"helps  make  profitable  a  well-rounded  operation  in  Oldbury,  England, 
the  only  surviving  chemical  works  using  the  Leblanc  soda  process. 
The  salt  cake  is  burned  in  furnaces,  the  soda  bleached  out,  the  chlorine 
recovered,  and  the  sludge  of  partially  decomposed  carbonaceous  matter 
containing  a  large  percentage  of  sulphite  of  lime  is  treated  in  closed 
agitators  with  carbonic-acid  gas  obtained  from  burning  lime  rock  in 
a  closed  kiln.  The  hydrogen  disulphide  driven  off  in  this  operation 
of  precipitating  the  carbonate  of  lime  is  burned  in  a  Klaus  kiln,  air  in 
proper  proportions  enters  with  the  gas,  and  flowers  of  sulphur  is  the 
final  product  of  this  part  of  the  operation  ".  A  further  utilization  of 
by-products  at  this  plant  occurs  when  the  carbonate  of  lime  so  pre- 

*  Engineering  and  Mining  Journal,  March  39,  1902. 


LIME-BURNING.  109 

cipitated  is  mixed  with  clay  and  burned  into  Portland  cement.  An 
editorial  note  appended  to  Mr.  Mather's  article  states  that  the  Har- 
greaves-Bird  alkali-works  at  Middlewich,  England,  also  use  waste  car- 
bon-dioxide gas  from  lime-kilns. 

Cost  of  lime-manufacture. — With  the  exception  of  a  comparatively 
few  large  and  well-managed  lime-plants,  lime-manufacture  in  the  United 
States  is  not  so  steadily  and  economically  handled  as  to  give  much 
basis  for  generalizations  concerning  costs.  The  result  is  that  the  data 
obtainable  are  rarely  definite  enough  to  be  of  much  service.  The  follow- 
ing is  probably  as  fair  a  statement  of  the  case  as  can  be  made. 

The  principal  items  to  be  considered  in  estimating  the  cost  of  lime- 
manufacture  are: 

(1)  Interest  on  cost  of  plant  and  quarry. 

(2)  Cost  of  quarrying  limestone. 

(3)  Cost  of  fuel  for  burning. 

(4)  Labor  costs,  exclusive  of  quarry. 

The  interest  on  cost  of  plant  and  quarry  will  vary  greatly  according 
to  the  steadiness  with  which  the  plant  is  operated.  This  is,  of  course, 
true  with  regard  to  the  same  item  in  the  cement  industry,  but  lime- 
plants  are  in  general  subject  to  greater  fluctuations  in  output.  The 
estimates  given  below  of  interest  charges  per  ton  of  lime  are  therefore 
given  a  very  wide  limit,  but  it  is  believed  to  be  impracticable  to  place 
them  more  definitely. 

The  cost  of  quarrying  is  also  variable,  but  within  narrower  limits. 
In  large,  carefully  managed  quarries  located  near  the  kilns,  and  with 
stone  and  stripping  so  arranged  as  to  admit  of  cheap  extraction,  the 
cost  of  quarrying  the  limestone  and  transporting  it  to  the  kiln  may  fall 
as  low  as  25  cents  per  ton.  This  cost  is  attained  in  Portland-cement 
quarries  in  the  Lehigh  district  of  Pennsylvania,  and  in  a  number  of 
'natural-cement  and  lime  quarries  elsewhere.  On  pages  378,  379  will 
be  found  further  details  as  to  cost  of  quarrying,  one  of  the  examples 
being  of  the  costs  at  a  quarry  worked  both  for  Portland  cement  and 
for  lime.  With  average  skill  in  locating  and  managing  the  quarry, 
it  is  probable  that  the  cost  of  quarrying  need  never  rise  above  40  or 
45  cents  per  ton  of  rock.  Allowing  for  waste  and  loss  by  under  or  over- 
burning,  2  tons  of  limestone  will  be  required  to  make  1  ton  of  lime. 
This  would  give  as  the  probable  limits  of  cost  of  quarrying  50  to  90 
cents  per  ton  of  burned  lime. 

Wood  is  still  used  for  fuel  at  many  lime-kilns,  in  which  case  the  cost 
of  fuel  may  be  merely  nominal  or  may  be  very  high.  When  coal  is 
used  for  fuel  in  a  modern  kiln,  the  coal  consumption  per  ton  of  burned 


110  CEMENTS,  LIMES,  AND   PLASTERS. 

lime  may  vary  from  300  to  500  Ibs.  These  limits  have  been  assumed 
in  the  estimate  below,  while  the  cost  of  coal  has  been  taken  as  varying 
from  $2  to  $3  per  ton.  These  prices  are  fairly  representative  for 
most  of  the  lime-plants  of  the  country. 

Labor  costs  are  estimated  with  a  rather  liberal  maximum  limit. 

The  final  results  of  these  calculations  are  shown  below. 

TOTAL  COST  OF  LIME-MANUFACTURE  PER  TON. 

Interest  on  cost  of  plant  and  quarry $0 . 05  to  $0 . 20 

Taxes,  minor  supplies,  etc 0.10"     0 . 25 

Cost  of  quarrying  two  tons  of  limestone.  ...     0 . 50  "     0 . 90 

Cost  of  fuel  for  burning 0". 30- "    0 . 75 

Cost  of  labor,  exclusive  of  quarrymen 0.25  "     0 . 80 

Total  cost  per  ton  of  burned  lime,  in 

bulk  (2000  Ibs.) . $1.20  "  $2.90 

This  corresponds  to  costs  of  4.2  to  10.15  cents  per  bushel  of  70  Ibs. 
The  minimum  estimate  represents  what  might  be  attained  by  a  good 
modern  plant,  run  steadily  and  under  exceptionally  favorable  conditions 
as  regards  quarrying,  fuel,  and  labor.  The  maximum  estimate  could 
easily  be  exceeded  by  the  small  or  unsteadily  operated  plants.  The 
average  cost  throughout  the  entire  country  is  probably  in  the  neigh- 
borhood of  6  to  8  cents  per  bushel. 

General  estimates  of  costs  of  lime-manufacture  by  the  use  of  Hoff- 
man kilns  will  be  found  on  pages  106  and  108. 

Actual  costs  of  lime-manfuacture  in  1900. — In  connection  with  the 
above  estimates  of  cost  it  is  of  interest  to  compare  certain  statistics 
collected  by  the  Census  Bureau  in  1900  and  published  in  vol.  7,  Reports 
Twelfth  Census,  pp.  274-277.  The  tables  on  the  pages  cited  give  total 
costs  of  various  elements  in  lime-  and  cement-manufacture  in  all  the 
states  during  1900.  As  the  figures  for  lime,  natural  cement,  and  Port- 
land cement  are  tabulated  together,  most  of  the  tables  are  of  little 
value  for  our  present  purpose.  In  the  ten  states  considered  below, 
however,  no  natural-  or  Portland-cement  plants  were  in  operation  during 
1900,  so  that  the  statistics  for  these  states  must  necessarily  apply  only 
to  the  lime  industry.  The  data  relating  to  these  ten  states  have  ac- 
cordingly been  slightly  rearranged  and  are  shown  in  the  following  table. 

As  the  total  quantities  of  lime  produced  are  not  stated,  it  is  impos- 
sible to  reduce  the  total  costs  given  in  the  table  to  costs  per  ton 
or  bushel  of  product.  A  simple  calculation,  however,  enables  us  to 
reduce  them  to  percentages  of  the  total  cost,  so  that  the  relative  im- 
portance of  the  various  elements  making  up  this  total  can  be  readily 


LIME-BURNING. 


Ill 


TABLE  35. 
COST  OF  LIME-MANUFACTURE  DURING  1900  IN  TEN  STATED. 


State  

Arkansas. 

Con- 

Iowa 

Maine 

Massachu- 

necticut. 

setts. 

Number  of  plants  

5 

11 

28 

20 

11 

Total  capital 

$53  894 

$250  392 

$663  830 

«i  040  007 

<tt1  I  K   fiQQ 

In  land 

11  598 

71  720 

89  100 

485  338 

20  100 

In  buildings 

10  865 

65  550 

159  325 

681  515 

28  700 

In  machinery 

9396 

26  915 

261  785 

143  225 

16  800 

In  cash   etc 

22  125 

86  207 

153  620 

631  929 

50  03Q 

Salaried  officials 

6 

12 

38 

34 

3 

Total  salaries 

$3  075 

$9  640 

$26  588 

$26  296 

$2  640 

Laborers  
Total  wages 

78 
$15  600 

171 

$71,938 

302 
$145  382 

582 
$248  371 

130 
$69  823 

Rent,  taxes,  etc  

$6,409 

$21,932 

$68,488 

$97,878 

$7,630 

Limestone,  cost  of  
Fuel,  cost  of  
Mill  supplies,  etc 

$21,097 
8,150 

$86,759 
59,005 
963 

$134,300 
41,564 
4,345 

$347,344 
196,991 
33  101 

$67,826 
54,257 
40 

Freight                 

250 

2,025 

1,305 

68803 

310 

Value  of  product  

$70,900 

$286,640 

$543,267 

$1,226,972 

$261  477 

State 

Missouri. 

Rhode 

Tennessee. 

Vermont 

West  Vir- 

Island. 

ginia. 

Number  of  plants  

31 

3 

12 

13 

7. 

Total  capital  ,  

$797,926 

$26,150 

$158,886 

$176,825 

$256,860  ' 

In  land 

201  852 

8,000 

39,300 

51  900 

142,500 

In  buildings 

232,119 

4,000 

27,680 

31,450 

28,500 

In  machinery 

107,  G75 

2,500 

20,751 

19,925 

9,160 

In  cash,  etc  

-    256,280 

11,650 

'  71,155 

73,550 

76,700 

Salaried  officials  

48 

1 

4 

2 

15 

Total  salaries        

$46,350 

$360 

$2,350 

$1,400 

$9,260 

Laborers                

583 

40 

167 

182 

128 

Total  wages            .    ... 

$206,837 

$16,230 

$50,665 

$57,257 

$47,200 

Rent,  taxes,  etc.  ...... 

$40,045 

$9,752 

$2,492 

$9,367 

$1,400 

Limestone,  cost  of  
T^iiol   cost  of 

$100,174 
109,974 

$8,314 
8,700 

$16,614 
20,305 

$36,8C4 
45,112 

$6,175 
24,840 

Mill  supplies,  etc  

2,960 

125 

1,110 

7,636 

30 

Freight         

20,802 

1,857 

6,000 

3,800 

_^ 

Value  of  product 

$600,432 

$48,089 

$166,423 

$207,524 

$109,393 

112 


CEMENTS,  LIMES,  AND  PLASTERS. 


noted.  In  Table  36,  below,  this  has  accordingly  been  done.  The 
interest  charges  have  been  taken  at  6  per  cent  of  the  total  capital,  and 
no  specific  allowance  has  been  made  for  depreciation  or  repairs,  as  these 
items  for  the  year  in  question  must  appear  under  one  of  the  other  head- 
ings. The  value  of  the  product  has  also  been  calculated,  in  percentages 
of  the  total  cost. 

TABLE  36. 

'  •  r* 

ELEMENTS   OF  COST  OF    LIME-MANUFACTURE.   EXPRESSED    IN  PERCENTAGES   05 

TOTAL  COST. 


Ark. 

Conn. 

Iowa. 

Maine. 

Mass. 

Mo. 

R.I. 

rr~ 

Tenn. 

Vt. 

W.Va. 

Aver- 

ap"5. 

Interest  

5.6 

5.6 

8.6 

10.3 

3.3 

8.5 

3.4 

9    1 

6  1 

14  2 

7  47 

Salaries  

5.3 

3.6 

5.9 

2.3 

1.3 

8.1 

0.8 

2  3 

0  8 

8  6 

3  90 

Wages  

26.9 

26.8 

31.4 

21.9 

33.3 

35.9 

36.1 

48.3 

32  9 

43  7 

33  72 

Taxes,  etc.  .  . 
Limestone  .  .  . 
Fuel  
Supplies  
Freight    .... 

11.1 
36.5 
14.1 
0.0 
0  5 

8.2 
32.5 
22.1 
0.4 

0.8 

14.8 
29.1 
9.0 
0.9 
0.3 

8.6 
30.6 
17.3 
2.9 
6.1 

3.7 
32.4 
25.9 
0.0 
0  1 

6.9 
17.4 
19.1 

0.5 
3  6 

21.7 
18.4 
19.3 
0.3 

2.4 
15.8 
19.3 
1.1 

1  7 

5.3 
21.1 
25.9 
4.4 
3  5 

1.3 

5.7 
23.0 
0.0 
3  5 

8.40 
23.95 
19.50 
1.05 
2  01 

Total  cost. 

100.0 

100.0 

100.  0 

100.0 

100.0 

100.0 

100.0 

100.0 

1CO.O 

100.0 

100.00 

Value      of 
product.  .  . 

122.7 

107.1 

117.6 

108.1 

124.8 

104.  C 

106.7 

158.6 

1.19: 

1.012 

117.00 

Statistics  of  the  Lime  Industry. — The  importance  of  the  lime 
industry  might  easily  be  underrated  were  it  not  that  very  accurate 
statistics  on  the  subject  are  available.  These  show  that  for  some  years 
past  the  value  x  of  the  annual  production  of  lime  in  the  United  States 
has  been  in  the  neighborhood  of  $10,000,000. 

In  Table  37  is  given  the  value  of  the  lime  production  in  the  United 
States  for  the  years  1902  and  1903  by  States  and  Territories.  These 
figures  are  taken  from  the  volumes  on  "  Mineral  Resources  of  the  United 
States",  issued  annually  by  the  U.  S.  Geological  Survey,  and  may  be 
accepted  as  being  a  close  approximation  to  the  actual  production. 

In  considering  these  figures  it  should  not  be  forgotten  that  they 
include  all  the  lime  burned  in  the  country  for  whatever  purpose  the 
product  may  be  employed.  It  is  probable  that  of  the  $10,105,190, 
at  which  the  total  lime  production  for  1903  is  valued,  about  $7,000,000 
would  represent  the  value  of  the  lime  used  for  structural  purposes — i.e., 
as  mortar,  plaster,  and  in  the  lime-sand  brick  industry.  Much  of  the 
remainder  of  the  product  is  used  in  various  chemical  industries,  not- 
ably in  the  manufacture  of  alkali,  gas,  paper,  sugar,  leather,  etc.,  etc., 
while  a  large  proportion  is  used  as  a  fertilizer.  The  proportion  of  lime 


LIME-BURNING. 


113 


used  for  structural  purposes  to  that  used  for  chemical  and  agricultural 
purposes  will  vary  in  the  different  states,  and  cannot  be  accurately 
determined.  Pennsylvania,  Ohio,  New  York,  and  Michigan  are  prob- 
ably the  largest  producers  of  lime  for  non-structural  uses. 

TABLE  37. 
LIME  PRODUCTION  OF   THE  UNITED  STATES. 


1902. 

1903. 

1902. 

1903. 

Alabama  

$235,568 

$217,326 

Nevada 

$2  800 

«o  400 

Arizona        

1,260 

New  Jersey 

12^  47S 

19O  81  fi 

Arkansas  

82,853 

89,337 

New  Mexico 

1  000 

California    

395,995 

396,750 

New  York 

604  7^ 

fiQS  fi74 

Colorado  
Connecticut  

46,866 
203,899 

53,637 

152,568 

North  Carolina.  .  . 
Ohio.  . 

2,090 
1  144  495 

eoo 

1  007  316 

Florida     

37,933 

44,137 

Oklahoma 

25 

4  000 

Georgia     

71,724 

62,902 

Oregon 

20  133 

1  0  RQA 

Idaho        

13,049 

18,2CO 

Pennsylvania 

1  446  333 

1   4.K1   f)Af\ 

Illinois   

485,644 

481,439 

Rhode  Island 

QO  400 

Indiana  

312,189 

314,206 

South  Carolina 

}     70,124 

4Q  QQn 

Indian  Territory. 

SCO 

South  Dakota 

21  300 

13  051 

Iowa       

114,146 

98,630 

Tennessee 

235  615 

198  663 

Kansas  

7,358 

14,480 

Texas.  .  . 

82  SCO 

74  118 

Kentucky        .  .  . 

15,893 

50988 

Utah 

99  463 

493  290 

Maine  

742,132 

791,690 

Vermont  

219  306 

180  769 

Maryland  

Massachusetts.  .  .  . 
Michigan  
Minnesota  

332,251 
324,480 
306,232 
77,214 

321,713 
262,815 
351,209 
66,719 

Virginia  
Washington  
West  Virginia.  .  .  . 
Wisconsin  

241,984 
186,070 
190,368 
549,357 

338,126 
226,948 
166,332 
559  494 

Missouri 

515,780 

646  048 

Wyoming 

2  250 

12033 

Montana 

8  775 

21  100 

Nebraska  

550 

1,624 

Total  

$9,573,011 

$10,105,190 

An  examination  of  Table  37  will  show  that  during  the  year  1903 
lime  was  burned  in  44  states  and  territories.  Only  six  political  divisions 
failed  to  appear  as  lime  producers — Delaware,  Louisiana,  Mississippi, 
New  Hampshire,  North  Dakota,  and  the  District  of  Columbia.  Of 
these  six  the  District  of  Columbia  is  known  to  contain  no  limestone, 
while  in  Delaware  the  limestone  outcrops  are  few  and  unimportant. 
The  only  limestone  occurring  in  North  Dakota  is  too  impure  for  most 
purposes,  being  in  fact  a  natural-cement  rock.  Louisiana  contains  a 
few  small  areas  of  limestone.  In  New  Hampshire,  however,  limestones 
are  much  commoner;  while  in  Mississippi  several  important  limestone 
areas  occur  but  are  not  at  present  utilized. 

The  rank  of  the  various  states  in  regard  to  value  of  lime  produced 
was,  for  the  year  1903,  as  follows: 

(1)  Pennsylvania,  (2)  Ohio,  (3)  Maine,  (4)  New  York,  (5)  Missouri, 
(6)  Wisconsin,  (7)  Utah,  (8)  Illinois,  (9)  California,  (10)  Michigan, 


114  CEMENTS,  LIMES,  AND  PLASTERS. 

(11)  Virginia,  (12)  Maryland,  (13)  Indiana,  (14)  Massachusetts,  (15) 
Washington,  (16)  Alabama,  (17)  Tennessee,  (18)  Vermont,  (19)  West 
Virginia,  (20)  Connecticut,  (21)  New  Jersey,  (22)  Iowa,  (23)  Arkansas, 
(24)  Texas,  (25)  Minnesota,  (26)  Georgia,  (27)  Colorado,  (28)  Kentucky, 
(29)  Florida,  (30)  South  Carolina,  (31)  Rhode  Island,  (32)  Montana, 
(33)  Idaho,  (34)  Kansas,  (35)  Oregon,  (36)  South  Dakota,  (37)  Wyoming, 
(38)  Oklahoma,  (39)  Nevada,  (40)  Nebraska,  (41)  Arizona,  (42)  New 
Mexico,  (43)  Indian  Territory,  '(44)  Not th  Carolina. 

It  may  be  stated  that  the  production  assigned  to  Utah  for  1903 
($493,290)  is  incredibly  large,  and  that  the  state  would  in  reality  prob- 
ably rank  about  twenty-fifth  instead  of  ninth  if  more*- detailed  statistics 
could  be  obtained.  The  rank  assigned  to  Kansas,  on  the  other  hand, 
seems  remarkably  low. 


CHAPTER  VIII. 
COMPOSITION  AND  PROPERTIES  OF  LIME. 

THE  lime  (or  "  quicklime  ")  resulting  from  the  burning  of  a  pure 
limestone  is  a  white  solid,  with  a  specific  gravity  of  3.09  to  3.15.  As 
packed,  it  will  weigh  about  60  Ibs.  per  cu.  ft.,  or  70-75  Ibs.  per  bushel. 
When  made  from  a  limestone  rock,  the  lime  should  be  in  lumps,  the 
occurrence  of  powder  or  dust  proving  that  the  lime  has  been  exposed 
to  the  air  so  much  since  burning  that  air-slaking  has  begun.  When 
the  lime  has  been  made  from  shells,  marl,  highly  crystalline  marbles, 
soft  chalk,  or  shelly  limestones,  however,  it  will  often  come  from  the 
kilns  in  small  fragments,  which  in  this  case  is  no  sign  of  deterioration. 

If  the  raw  material  is  impure,  containing  much  clayey  matter  or 
iron  oxide,  the  resulting  lime  will  not  be  white,  but  will  vary  from 
yellowish  to  gray  or  brown  in  color,  according  to  the  amount  and  kind 
of  impurities  present.  It  will  also,  in  general,  slake  much  slower  than 
would  a  purer  product. 

High-calcium  vs.  magnesian  limes. — The  relative  merits  of  these 
two  classes  have  been  frequently  discussed  in  text-books  and  technical 
journals,  and  are  still  subjects  of  controversy.  The  facts  of  the  case, 
however,  seem  to  be  simple  enough  and  may  be  summarized  as  follows: 

High-calcium  limes  slake  rapidly  on  the  addition  of  water,  and  evolve 
much  heat  during  slaking  They  also  expand  greatly,  giving  a  large 
bulk  of  slaked  lime.  Magnesian  limes  slake  very  slowly,  and  evolve 
very  little  heat  during  the  process.  Their  expansion  is  also  less;  so 
that,  taking  equal  weights,  they  give  less  bulk  of  slaked  lime. 

Owing  to  the  slowness  and  coolness  with  which  the  magnesian  limes 
slake,  there  is  some  danger  that  the  average  mortar-mixer  *  will  not 
give  them  sufficient  time  to  slake  thoroughly.  Owing  to  the  fact  that 
they  make  less  bulk  of  slaked  product  than  do  the  high-calcium  limes, 
the  average  contractor  or  builder  thinks  that  they  are  too  expensive. 
But,  on  the  other  hand,  they  are  very  much  stronger  in  long-time  tests 

*  A  human,  not  mechanical,  mortar-mixer  is  here  spoken  of. 

115 


116 


CEMENTS,  LIMES,  AND   PLASTERS. 


than  the  high-calcium  limes,  and  will  therefore  carry  much  more  sand. 
This  fact  is  brought  out,  for  one  instance,  by  the  tests  given  on  p.  122. 

Composition  of  commercial  high-calcium  limes. — The  non-mag- 
nesian  or  high-calcium  limes  as  marketed  will  rarely  carry  less  than 
90  per  cent  of  lime  oxide  (CaO),  while  they  commonly  carry  over  95 
per  cent.  The  remaining  5  or  10  per  cent  is  made  up  of  magnesia 
MgO),  silica  (Si02),,  alumina  .(A^OaX*  iron  oxide  (Fe2O3),  and  a  little 
carbon  dioxide  and  water.  In  the  following  table  a  number  of  analyses 
of  representative  high-calcium  limes  are  given.  • 

TABLE  38. 
ANALYSES  OF  HIGH-CALCIUM  LIMES  (U.  S.). 


No. 

Silica  (SiO2). 

Alumina  (Al^Os) 
and  Iron 
Oxide  (Fe2O3). 

Lime  (CaO). 

Magnesia 
(MgO). 

Carbon  Dioxide 
(C02)  and 
Water. 

1* 

0.18 

0.26 

98.44 

0.98 

0.32 

2 

0.37 

0.21 

97.11 

0.56 

n.  d. 

3 

1.69 

n.  d. 

96.11 

0.11 

n.  d. 

4 

1.01 

1.30 

97.72 

n.  d. 

n.  d. 

5 

0.81 

0.75 

98.30 

n.  d. 

n.  d.    ' 

6 

1.14 

0.17 

95.66 

0.76 

3.00 

7 

0.36 

0.15 

98.13 

0.42 

0.80 

8 

0.81   - 

0.47 

96.63 

0.88 

0.12 

9 

1.96 

0.94 

95.60 

0.14 

1.36 

10 

3.42 

1.21 

94.26 

0.32 

0.79 

11 

0.79 

0.26 

97.48 

1.40 

n.  d. 

12 

3.2 

1.4 

94.0 

1.40 

n.  d. 

13 

1.88 

2.03 

91.93 

3.06 

n.  d. 

14 

1.70 

98.46 

0.64 

1.20 

15 

0?80' 

97.  CO 

0.36 

1.24 

16 

0.23 

1.29 

97.64 

0.80 

n.  d. 

17 

1.06  ' 

0.58 

95.50 

tr. 

2.08 

18 

1.93 

0.27 

94.07 

0.79 

3.04 

19 

3.20 

0.80 

94.80 

1.21 

n.  d. 

*20 

0.43 

0.36 

97.82 

0.12 

n.  d. 

21 

0.56 

0.22 

97.89 

1.05 

n.  d. 

22 

0.25 

0.15 

97.46 

0.73 

1.41 

23 

0.15 

0.16 

97.82 

0.85 

1.02 

24 

tr. 

tr. 

98.47 

1.12 

0.45 

25 

0.10 

0.12 

99.29 

0.46 

n.  d. 

26 

0.02 

tr. 

98.84 

0.12 

1.02 

27 

0.38 

0.65 

98.26 

0.30 

n.  d. 

28 

0.14 

tr. 

99.23 

0.60 

n.  d. 

29 

0.27 

0.19 

98.14 

1.40 

n.  d. 

30 

0.18 

0.26 

98.44 

0.98 

0.32 

31 

0.30 

0.42 

98.24 

0.56 

0.54 

32 

2.22 

n.  d. 

96.93 

0.85 

n.  d. 

33 

0.42 

0.33 

97.71 

1.15 

0.32 

34 

0.78 

0.52 

98.40 

0.10 

n.  d. 

35 

1.38 

0.62 

97.80 

0.18 

n.  d. 

For  references  see  next  page. 


COMPOSITION  AND  PROPERTIES  OF  LIME.  117 

Limes  of  this  type  slake  rapidly  when  water  is  added  and  develop 
much  heat  during  slaking.  They  also  expand  notably,  so  that  the 
resulting  paste  (slaked  lime)  will  be  much  more  bulky  than  the  original 
lime. 

Lean  or  poor  limes. — A  lime  containing  over  5  per  cent  of  such 
impurities  as  silica,  alumina,  and  iron  oxide  will  usually  be  dark  in  color, 
comparatively  slow  slaking,  and  difficult  to  trowel  in  working.  Such 
limes  are  known  as  "  lean  "  or  "  poor  "  limes.  In  a  few  cases  the  impuri- 
ties are  so  evenly  and  finely  distributed  throughout  the  original  lime- 
stone that  on  burning  the  limestone  a  certain  amount  of  combination 
takes  place  between  the  lime  (CaO)  and  the  impurities.  This  gives 
slightly  hydraulic  properties  to  the  product.  Ordinarily,  however, 
no  such  chemical  combination  takes  place  on  burning,  and  the  impuri- 
ties simply  serve  to  depreciate  the  quality  of  the  lime  produced. 

The  following  analyses  (Table  39)  are  of  lean  limes  produced  at 
various  localities  in  the  United  States. 

REFERENCES  FOR  TABLE  38. 

1.  Longview  Lime  Works,  Longview,  Ala.     W.  C.  Stubbs,  analyst. 

2.  "  "         A.  L.  Metz, 

3.  Standard  Lime  Co.,  Fort  Payne,  Ala.     A.  D.  Brainerd,  analyst.     20th  Rep.  U.  S.  Geol.  Sur  , 

pt.  6,  p.  355. 

4.  Alton,  Ills.     S.  E.  Swartz,  analyst.     20th  Rep.  U.  S.  Geol.  Sur.,  pt.  6,  p.  378. 

5.  Star  Lime  Co.,  Montgomery  Co.,  Ky.     R.  Peter,  analyst.     Report  A,  Ky.  Geol.  Survey,  p.  171. 
€.  Hutchinson  Bros.,  New  Lenox,  Mass.     W.  M.  Habirshaw,  analyst.     20th  Rep.  U.  S.  Geol 

Sur..  pt.  6,  p.  411. 
7.  J.  Follet  &  Son,  Renfrew,  Mass.      20th  Rep.  TL  S.  Geol.  Sur.,  pt.(6,  p.  410. 

9.  Collins  Lime  Works,  Alpena,  Mich.  "         "         "         "         "         "      p.  413. 
10. 

11.  Chazy  Marble  Lime  Co.,  Chazy,  N.  Y.     E.  Tonceda,  analyst.     Bull.  44,  N.  Y.  State  Museum, 

p.  776. 

12.  Brown  Lime  Works,  Leroy,  N.  Y.     Bull.  44,  N.  Y.  State  Museum,  p.  784. 

13.  Alvord  &  Co.,  Jamesville,  N.  Y.     F.  E.  Engelhardt,  analyst.     20th  Ann.  Rep.  U.  S.  Geol.  Sur., 

pt.  6,  p.  428. 

14.  15.  Glens  Falls,  N.  Y.     J.  H.  Appleton,  analyst.      17th  Ann.  Rep.  U.  S.  Geol.  Sur.,  pt,  3,  p.  801. 

16.  Robinson  &  Ferris,  Mechanicville,  N.  Y.      M.  L.  Griffin,  analyst.      20th  Ann.  Rep.  U.  S.  Geol. 

Sur.,  pt.  6,  p    428. 

17,  18.  Keenan  Lime  Co.,  Smith's  Basin,  N.  Y.     20th  Ann.  Rep.  U.  S,  Geol.  Sur.,  pt.  6,  p.  428. 

19.  Stitt  &  Price,  Columbus,  Ohio.     C.  L.  Mees,  analyst.     Vol.  4,  Rep.  Ohio  Geol.  Sur.,  p.  617. 

20.  Arlington  Lime  Co.,  Erin,  Tenn.     J.  C.  Wharton,  analyst.     20th  Ann.  Rep.  U.  S.  Geol.  Sur., 

pt.  6,  p.  443. 

21.  Gager  Lime  Co.,  Sherwood,  Tenn.     20th  Ann.  Rep.  U.  S.  Geol.  Sur.,  pt.  6,  p.  444.    . 

22.  23.  Austin  White  Lime  Co.,  McNeil,  Texas.     J.  A.  Bailey,  analyst."    20th  Ann.  Rep.  U.  S. 

Geol.  Sur.,  pt.  6,  p.  444. 
24,  25,  26.     J.  P.  Rich,  Swanton,  Vt.     20th  Ann.  Rep.  U.  S.  Geol.  Sur.,  pt.  6,  p.  455. 

27.  Brandon  Lime  Co.,  Leicester  Junction,  Vt.     C.  T.  Lee,  analyst.     20th  Ann.  Rep.  U.  S.  Geol. 

Sur.,   pt,    6,   p.    455. 

28.  W.  B.  Fonda,  St.  Albans,  Vt.     F.  C.  Robinson,  analyst.     20th   Ann.  Rep.  U.  S.  Geol.  Sur., 

29.  Follet  Bros.,  North  Pownal,  Vt.     R.  Schuppans,  analyst.     20th  Ann.  Rep.  U.  S.  Geol.  Sur., 

30    Ditto  Lime  Co.,  Marlowe,  W.  Va.     J.  A.  Ditto,  analyst.     20th   Ann.  Rep.  U.  S.  Geol.  Sur., 
pt.  6,  p.  459. 

31.  J.  B.  Speed  &  Co.,  Milltown,  Ind.     Burk  &  Arnold,  analysts.     28th  Ann.   Rep.  Indiana  Dept. 

Geology,  p.  244. 

32.  Union   Cement   and   Lime  Co.,   Salem,   Ind.     Chauvenet   Bros.,    analysts.     28th  Ann.   Rep. 

Indiana  Dept.  Geology,  D.  250. 

33.  Mitchell  Lime  Co.,  Rabbitville,  Ind.     E.  F.  Buchanan,    analyst.     28th  Ann.   Rep.  Indiana 

Dept.  Geology,  p.  254. 

34.  Horseshoe  Lime  and  Cement  Co.,  Bedford,  Ind.     Chauvenet  Bros.,  analysts.     28th  Ann.  Rep. 

Indiana  Dept,  Geology,  p.  256. 

35.  Horseshoe  Lime  arid  Cement  Co.,  Bedford,  Ind.     T.    W.  Smith,  analyst.     28th    Ann.  Rep. 

Indiana  Dept.  Geology,  p.  256. 


118 


CEMENTS,  LIMES,  AND   PLASTERS. 


TABLE  39. 
ANALYSES  OF  LEAN  LIMES. 


Silica  (3iO2)            .    .    . 

2  43 

3  24 

3  50 

1  62 

10  20 

5  50 

6  29 

Alumina  (Al2O3)      •  •  •  1 

/O  42 

Iron  oxide  (Ve2O3).  .  .  J 

6.80 

4.26 

3.92 

2.62 

3.60 

1.99 

\0.33 

Lime  (CaO)  

81.38 

81.92 

83.20 

.82.40 

81.33 

84.40 

85.49 

Magnesia  (MgO)  

1.34 

n.  d. 

n.  d. 

n.  d. 

1.17 

1  .80 

0.31 

The  last  of  the  above  analyses  is  of  a  lime  made  by  burning  oyster- 
shells  in  a  mixed-feed  kiln.  In  this  case  the  impurities  shown  in  the 
lime  are  largely  the  result  of  coal-ash  taken  up  by  th&  lime  during  manu- 
facture. (See  pp.  94,  95.) 

Composition  of  commercial  magnesian  limes. — In  discussing  the 
classification  of  limes,  pp.  97,  98,  it  was  stated  that  limes  carrying  over 
5  per  cent  of  magnesia  were  to  be  grouped  commercially  as  mag- 
nesian limes.  In  the  present  place  this  statement  will  bear  discussing 
in  somewhat  more  detail. 

In  theory  a  limestone  can  carry  anywhere  from  0  to  45.65  per  cent 
of  magnesium  carbonate  (MgCOs).  In  the  first  case  it  would  have  the 
composition  of  the  mineral  calcite  (  =  CaCO3),  in  the  second  that  of 
the  mineral  dolomite  (CaCOs  +  MgCOs) ,  while  the  intermediate  stages 
falling  between  these  two  limits  (0  and  45.65  per  cent  MgCOs)  would  be 
known  simply  as  magnesian  limestones.  A  further  theoretical  con- 
clusion is  that  such  intermediate  stages  would  occur  approximately  as 
commonly  as  the  extreme  stages. 

In  practice,  however,  we  find  that  this  last  theoretical  deduction 
does  not  hold.  If  a  large  series  of  limestone  analyses  be  compared, 
it  will  be  found  that  by  far  the  great  majority  of  them  are  of  the  two 
extremes  of  the  series.  That  is  to  say,  actual  limestones  are  either 
very  low  in  magnesia  or  very  high  in  it.  This  condition  causes  the 
product  made  by  burning  limestone  to  fall  usually  in  one  of  the  two 
following  classes: 

A.  High-calcium  limes:   magnesia  less  than  5  per  cent. 

B.  High-magnesium  limes:    magnesia  over  30  per  cent. 
Intermediate  limes   are   of  course  burned,  but   they  are   compara- 
tively rare.     Analyses  10,  11,  12,  and  13  of  Table  40  are  of  such  inter- 
mediate types,  carrying  respectively  7.41,  7.52,  13.42,  and  6.08  per  cent 
of  magnesia. 

The  composition  of  the  typical  magnesian  limes  is  well  shown  by 
analyses  1-9,  inclusive,  of  Table  40. 

Lime-slaking. — The  subject  of  lime-slaking  has  always  been  a  mat- 
ter of  importance  in  connection  with  the  ordinary  use  of  lime  in  making 


COMPOSITION  AND  PROPERTIES   OF  LIME. 


119 


TABLE  40. 
ANALYSES  OF  MAGNESIAN  LIMES  (U.  S.). 


Number. 

Silica  (SiO2). 

Alumina  (A12O3) 
and  Iron  Oxide 
(Fe203). 

Lime  (CaO). 

Magnesia 
(MgO). 

Carbon  Dioxide 
(C02),  Water, 
etc. 

1 

, 

56.57 

42.56 

0    10 

0.42 

2 

7.25 

1.24 

55.74 

34.07 

1,62 

3 

0.88 

56.81 

37.98 

2.84 

4 

0.80 

58.00 

38.45 

2.80 

5 

1.61 

0.17 

57.44 

40.36 

0  41 

6 

2.95 

1.35 

58.33 

37.37 

n.  d. 

7 

0.46 

1.10 

55.49 

42.31 

0.64 

8 

0.07 

2.62 

63.03 

34.15 

0.13 

9 

0.35 

0.49 

59.20 

38.38 

1.80 

10 

1.09 

1.74 

81.83 

13.42 

1  92 

11 

n.  d. 

0.38 

91.72 

7.52 

n.  d 

12 

1.78 

0.75 

90.07 

7.41 

n.  d. 

13 

0.15 

1.70 

90.20 

6.08 

0.30 

1.  Canaan  Lime  Co.,  Canaan,  Conn.     J.  S.  Adam,  analyst.     20th  Ann.  Rep.  U.  S.  Geol    Sur 

pt.  6,  p.  370. 

2.  Ladd  Lime  Works,  Bartow,  Ga.     N.  P.  Pratt,  analyst.     20th  Ann.  Rep.  U.  S.  Geol.  Sur., 

pt.  o,  p.  375. 

3.  Kelly  Island  Lime  Co.,  Sandusky,  Ohio.       J.  W.  Skinner,  analyst.       Private  communica- 

tion. 

4.  Marblehead  Lime  Co.    Sandusky,  Ohio.     J    W.  Skinner,  analyst.     Private  communication. 

5.  L.  McCollum  &  Co.,  Tiffin,  Ohio.     O.  Wulte,  analyst.     20th  Ann.   Rep.   U.  S.   Geol.  Sur., 

pt.  6,  p.  433. 

6.  McCoy  Lime  Co.,  Bridgeport,  Pa.     C.  I.  Reader,  analyst.     20th  Ann.  Rep.  U.  S.  Geol.  Sur., 

pt.  6,  p.  440. 

7.  Sheboygan  Lime  Works,  Sheboygan,  Wis.     G.  Bode,  analyst.     20th  Ann.  Rep.  U    S    Geol 

Sur.,  pt.  6,  p.  464. 

8.  Western  Lime  Co.,  Huntingdon,  Ind.     T.  W.  Smith,  analyst.     28th  Ann.  Rep.  Indiana  Dept. 

Geology,  p.   237. 

9.  Consolidated  Lime  Co.,  Huntingdon,  Ind.     R.  E.  Lyons,  analyst.     28th  Ann.  Rep.  Indiana 

Dept.  Geology,  p.  239. 

10.  Petoskey  Lime  Co.,  Bay  Shore,  Mich.     E.  J.  Schneider,  analyst.     28th  Ann.  Rep.  Indiana 

Dept.  Geology,  p.  413. 

11.  Williams  Lime  Works,  Rossie,  N.  Y.     Bull.  44,  N.  Y.  State  Museum,  p.  815. 

12.  West  Coxsackie,  Greene  Co.,  N.  Y.     18th  Ann.  Rep.  U.  S.  Geol.  Sur.,  pt.  5,  p.  1063. 

13.  Coble  Lime  Co.,  Delphi,  Ind.     T.  W.  Smith,  analyst.     28th  Ann.  Rep.  Indiana  Dept.  Geology, 

p.  233. 

mortar  for  structural  work.  During  the  past  few  years,  however,  it 
has  assumed  a  far  greater  importance  as  being  an  essential  part  of  the 
manufacture  of  "  hydrated  lime  "  and  "  lime-sand  bricks  ".  The  theo- 
retical aspects  of  the  slaking  of  lime  will  be  discussed  in  the  section 
below,  while  the  discussion  of  the  actual  methods  of  slaking  will  be 
found  on  pp.  120,  121  and  in  the  two  succeeding  chapters  (IX  and  X), 
which  deal  with  the  manufacture  and  properties  of  hydrated  lime  and 
of  lime-sand  brick  respectively. 

If  water  be  poured  upon  a  lump  of  .pure  quicklime,  lime  hydrate 
will  be  formed,  while  considerable  heat  will  be  evolved,  the  lime  will 
expand  notably  in  bulk,  and  the  lump  will  fall  into  powder.  The  chem- 
ical combination  that  takes  place  during  this  operation  is  represented 
in  a  formula  by 

CaO  +  H2O  =    Ca02H2. 

(Lime)  +  (Water)  =  (Lime  hydrate) 


120  CEMENTS,  LIMES,  AND  PLASTERS. 

With  absolutely  pure  lime  the,  amount  of  water  that  must  be  added 
in  order  to  change  all  of  the  quicklime  into  lime  hydrate  will  equal 
32.1  per  cent,  by  weight,  of  the  quicklime.  The  resulting  lime  hydrate 
will  therefore  consist  of  75.7  per  cent  lime  (oxide)  and  24.3  per  cent 
water.  Lime  hydrate  is  a  fine  white  powder,  with  a  specific  gravity 
of  2.078. 

Effect  of  impurities  present. — Th&  above  percentages  would  only 
hold  true  in  case  the  burned  lumps  consisted  entirely  of  quicklime  (CaO) . 
Actually  we  know  that  this  theoretical  purity  is  never  attainable  on 
a  commercial  scale.  The  original  limestone  always  contains  silica, 
alumina,  iron  oxide,  etc.,  in  quantities  more  or  less  large.  The  lime- 
stone is,  moreover,  never  perfectly  burned,  so  that  some  portions  of 
unburned  lime  carbonate  will  always  be  present  in  the  product. 

The  presence  of  these  impurities,  including  silica,  alumina,  iron 
oxide,  and  fragments  of  unburned  lime  carbonate,  operates  to  reduce 
the  amount  of  water  theoretically  required  for  perfect  slaking  of  the 
lime.  For  example,  a  perfectly  pure  lump  of  quicklime  100  Ibs.  in 
weight  ,would  require  32.1  Ibs.  of  water  for  complete  slaking.  If  the 
lump  contained  10  per  cent  of  impurities,  however,  it  would  require 
only  28.9  Ibs.  of  water. 

Expansion  of  volume. — The  impurities  also  serve  to  reduce  the 
expansion  of  volume  which  the  lime  would  otherwise  show.  A  pure 
lime,  if  slaked  by  adding  the  entire  quantity  of  water  at  once,  may 
increase  3^  times  in  volume;  if  slaked  gradually,  only  part  of  the  water 
being  added  at  a  time,  it  will  increase  much  less;  while  if  allowed  to 
air-slake  its  increase  in  volume  will  be  only  about  1.7  times  its  original 
volume.  An  impure  lime,  as  above  noted,  will  show  less  expansion, 
the  difference  being  in  direct  ratio  to  the  percentage  of  impurities. 

The  rapidity  and  intensity  of  the  slaking  will  also  be  less  with  an 
impure  than  with  a  pure  lime,  and  the  amount  of  heat  evolved  during 
slaking  will  be  decreased. 

Effect  of  the  presence  of  magnesia. — If  the  lime  contain  any  con- 
siderable percentage  of  magnesia,  slaking  will  take  place  more  slowly 
and  with  less  evolution  of  heat,  while  the  expansion  of  volume  will  be 
less.  In  consequence  of  the  slowness  of  the  slaking  more  care  is  necessary 
with  magnesian  than  with  high-calcium  limes  in  order  to  insure  that 
the  product  has  been  thoroughly  slaked. 

Methods  of  slaking  lime  in  ordinary  practice. — When  lime  is  used 
for  making  ordinary  building-mortar,  the  common  practice  is  to  add 
much  more  than  the  amount  of  water  theoretically  required.  The 
result  is  not  only  to  slake  the  lime  but  to  convert  the  slaked  lime  into 


COMPOSITION  AND  PROPERTIES  OF  LIME.  121 

a  thin  or  thick  paste,  according  to  the  amount  of  water  used.  When 
ordinary  laborers  are  slaking  lime  it  is  evident  that  this  method  possesses 
the  great  advantage  of  being  on  the  safe  side.  It  is  possible  that  the 
addition  of  the  surplus  water  weakens  the  mortar  somewhat,  but  on 
the  other  hand  it  insures  thorough  slaking,  or  would  insure  it  if  even 
reasonably  good  care  were  taken  during  the  operation.  The  trouble, 
however,  has  been  that  lime-slaking  is  not  regarded  as  an  art,  but  as  a 
disagreeable  necessity,  and  it  is  usually  carried  on  by  laborers  who 
are  not  even  supposed  to  know  anything  about  the  subject. 

The  result  of  these  conditions  is  that  the  slaked  lime  used  in  mortar 
rarely  even  approaches  its  theoretical  efficiency.  Either  so  much 
water  has  been  added  that  the  strength  of  the  product  is  impaired  or 
else  the  water-supply  or  mixing  has  been  insufficient  and  the  product 
is  not  thoroughly  slaked. 

A  realization  of  these  facts  has  caused  the  introduction  of  ready- 
slaked  lime,  prepared  carefully  at  the  lime-plants.  This  product  is 
discussed  in  the  following  chapter  under  the  head  of  "  Hydrated  lime". 
In  its  preparation  particular  care  is  given  to  insuring  that  the  product 
shall  be  thoroughly  slaked,  and  that  this  slaking  shall  be  done  with  as 
little  water  as  possible.  Several  distinct  methods  of  slaking  have 
accordingly  been  devised  and  are  in  use  at  different  lime-hydrating 
plants. 

In  ordinary  practice,  where  quicklime  is  slaked  on  the  work,  only 
one  general  method  is  followed,  though  books  on  construction  invari- 
ably list  and  describe  several  other  methods.  The  process  as  actually 
carried  out  is  to  form,  on  a  plank  floor  or  on  a  bed  of  sand,  a  circular 
wall  of  sand.  The  lime  is  shoveled  into  the  ring  thus  formed  and 
water  is  turned  on  from  a  hose  until  the  laborer  considers  the  amount 
sufficient.  The  lime  commences  to  slake  more  or  less  quickly  accord- 
ing to  its  composition,  and  when  the  process  is  completed  it  is  covered 
over  with  a  thin  layer  of  sand  until  required  for  mortar. 

Use  of  lime  mortars. — Lime  is  never  used  alone  as  a  binding  mate- 
rial, for  it  shrinks  greatly  on  drying  and  hardening,  and  this  shrinkage 
would  produce  cracks  if  nothing  were  added  to  the  mortar  to  counter- 
act it.  In  practice  sand  is  always  added  to  lime  mortars,  the  propor- 
tions for  ordinary  use  being  from  two  to  four  parts  sand  to  one  part 
lime  paste. 

The  hardening  of  lime  mortars  is  a  simple  process,  though  occa- 
sionally statements  of  opposite  tenor  may  be  found  in  print.  It  may 
be  accepted  as  proven  that  lime  mortars  harden  by  simple  recarbon- 
ation,  the  lime  gradually  absorbing  carbon  dioxide  from  the  atmosphere 


122 


CEMENTS,  LIMES,  AND  PLASTERS. 


and  becoming,  in  fact,  artificial  limestones.  As  this  absorption  can 
take  place  only  on  the  surface  of  the  masonry,  the  lime  mortar  in  the 
interior  of  a  wall  never  becomes  properly  hardened.  In  this  process 
the  sand  of  the  mortar  takes  no  active  part.  It  is  merely  an  inert  mate- 
rial, added  solely  in  order  to  prevent  shrinkage  and  consequent  crack- 
ing. In  this  connection  the  reader  may  be  referred  to  a  discussion 
on  pages  132,  133  of  the  theory  of  linie-sand  brick  manufacture. 

Strength  of  lime  mortars. — Few  recent  determinations  have  been 
made  on  this  point,  as  lime  is  steadily  decreasing  in  importance  as  an 
engineering  material.  t 

The  following  tests,  made  by  Mr.  George  S.  Mills  of  Toledo,  Ohio, 
have  been  recently  published.*  They  are  directly  related  to  the  point 
under  discussion  and  furnish  strong  evidence  of  the  superiority  of  the 
highly  magnesian  limes. 

The  limes  tested  were  made  by  burning  limestones  of  the  following 
composition : 


Constituents. 

Magnesian. 

High 
Calcium. 

Silica  (SiO2) 

0   45 

n  d 

Alumina  (A12O3)                    .    .    .  \ 

Iron  oxide  (Fe2O3)            J 

0.28 

n.  d. 

Lime  carbonate  (CaCO3)  
Magnesium  carbonate  (MgCO3).  .  . 

54.20 
45.06 

86.22 
9.27 

The  limes  resulting  from  burning  the  above  limestones  were  slakedr 
mixed  with  sand  in  the  proportion  of  one  part  slaked  lime  to  two  parts 
sand  by  weight,  and  made  into  briquettes,  which  were  tested  at  various 
ages,  with  the  results  shown  below.  The  figures  given  are  in  pounds 
per  square  inch  and  each  value  represents  the  average  of  the  tests  of 
from  four  to  six  briquettes. 

TABLE  41. 
TENSILE  STRENGTH  OP  MAGNESIAN  AND  HIGH-CALCIUM  LIMES.     (MILLS.) 


Age. 

High- 
calcium 
Lime. 

Magnesian 
Lime. 

4  weeks 

30| 

8       "     
3  months  
4        " 

36| 
39i 
39 

28| 
37£ 
51 

6        " 

501 

83 

1  year 

44* 

924 

*  Rhines,    G.    V.     Tensile    strength    of   high-calcium    and    magnesium   limes 
Municipal  Engineering,  vol.  28,  pp.  4-7.     Jan.  1905. 


COMPOSITION  AND  PROPERTIES  OF  LIME. 


123 


In  1895  a  series  of  experiments  *  on  the  strength  of  lime  mortars 
was  made  by  L.  C.  Sabin  in  connection  with  work  on  the  Saulte  Ste. 
Marie  canal.  The  results  of  these  tests  are  given  in  Table  42,  below. 

In  preparing  the  lime  120  Ibs.  of  water  was  added  to  40  Ibs.  quick- 
lime, and  after  a  few  days  the  excess  water  was  poured  off  and  the 
paste  passed  through  a  10-mesh  sieve  to  remove  lumps.  In  the  original 
tables  the  percentages  of  lime  and  water  in  the  various  lime  pastes 
are  given.  In  the  following  table,  however,  this  has  been  omitted, 
and  the  ratio  given  is  that  between  the  sand  and  the  dry  quicklime. 


TABLE  42. 
STRENGTH  OF  LIME  MORTARS. 


(SABIN.) 


Composition, 
Parts  by  Weight. 

Kind  of  Sand. 

Age. 

No.  of 
Tests. 

Tensile  Strength, 
Pounds  per  Square  Inch. 

Lime. 

Sand. 

Maxi- 
mum. 

Mini- 
mum. 

Aver- 
age. 

1 
1 
1 

1 
1 
1 
1 
1 
1 
1 
1 
1 
1 
1 
1 
1 
1 
1 
1 
1 
1 
1 
1 
1 

3 

6 
8.8 
8.8 
11.8 
17.7 
3 
6 
8.8 
8.8 
11.8 
17.7 
3 
3 
6 
6 
8.8 
8.8 
8.8 
8.8 
11.8 
11.8 
17.7 
17.7 

Standard 

28  days 
« 

29  days 
3  months 

5 
5 
5 
5 
5 
5 
5 
5 
5 
5 
5 
5 
5 
5 
5 
5 
5 
5 
5 
5 
4 
5 
4 
5 

58 

69 
62 
68 
54 
32 
50 
66 
76 
66 
68 
48 
52 
64 
59 
63 
60 
78 
87 
74 
63 
64 
40 
41 

26 
50 

37 
60 
30 
8 
24 
38 
55 
54 
52 
40 
42 
20 
40 
43 
46 
67 
58 
56 
39 
46 
34 
38 

46 
62 
47 
63 
39 
20 
37 
51 
64 
59 
56 
43 
47 
51 
47 
56 
52 
71 
67 
66 
47 
55 
36 
39 

*  i 

1  1 

Natural,  passing  10-mesh  . 
Standard 

t  i 

Crushed  limestone  

Screened,  20-40  mesh.  .  .  . 

it             (i         (  t 

Natural,  passing  10-mesh. 

Screened,  20-40  mesh.  .  .  . 

(  (             i  (         11 

Standard 

Crushed  limestone 

Standard 

Screened,  20-40  mesh  
Standard  

Screened,  20-40  mesh  

Natural,  passing  10-mesh. 

t<              a            (  ( 

Standard  

Screened,  20-40  mesh.  .  .  . 

Standard  

Screened,  20-40  mesh  .... 

*  Report  of  the  Chief  of  Engineers,  U.  S.  A.,  for  1896,  pt.  5,  p.  2839.     1896. 


CHAPTER  IX. 
HYDRATED   LIME:    ITS   PREPARATION  AND   PROPERTIES. 

IN  the  preceding  chapter  it  has  been  stated  that  quicklime  (CaO) 
combines  with  about  one-third  of  its  own  weight  of  wkter  to  form  slaked 
or  hydrated  lime  (CaH^C^).  It  has  been  further  stated  that  lime-slak- 
ing when  done  on  construction  work  by  ordinary  laborers  is  very 
inefficiently  accomplished.  This  has  always  been  realized,  but  it  has 
only  been  within  the  past  few  years  that  any  extensive  effort  has  been 
made  to  provide  a  more  satisfactory  article  for  the  contractor  or  builder. 

Under  the  names  of  "  new-process  lime ",  "  hydrated  lime ", 
"  limoid  ",  etc.,  a  large  number  of  lime-plants  have  within  recent  years 
placed  a  ready-slaked  lime  on  the  market.  When  this  product  is  care- 
fully prepared,  it  does  away  with  all  the  trouble,  waste,  and  unsatis- 
factory results  entailed  by  the  old  method  of  slaking  lump  lime  on  the 
work.  It  seems  probable,  therefore,  that  increased  knowledge  of  its 
valuable  properties  and  increased  care  in  its  preparation  will  result  in 
a  great  extension  of  its  production  and  a  corresponding  decrease  in 
the  amount  of  lime  marketed  in  the  unhydrated  form. 

Preparation  of  hydrated  lime. — In  preparing  hydrated  lime  on  a 
commercial  scale  three  stages  of  manufacture  are  necessary.  These  are: 

(1)  The  lump  quicklime  must  be  ground  to  a  fairly  uniform  small 
size. 

(2)  The  powder  or  grains  resulting  must  be  thoroughly  mixed  with 
sufficient  water. 

(3)  The  slaked  lime  must  finally  be  sieved  or  otherwise  brought  to 
a  uniform  fine  powder. 

Numberless  patents  have  been  issued  to  cover  one  or  more  of  the 
points  above  named,  but  the  general  stages  are  the  same  in  all.  These 
will  now  be  taken  up  separately  and  briefly  discussed. 

Grinding  the  quicklime. — Though  grinding  is  practiced  at  most  lime 
hydrate  plants,  great  variation  exists  in  the  extent  to  which  it  is  carried. 
In  some  plants  the  quicklime  is  simply  crushed  to,  say,  \  inch  or  1  inch 
size,  while  in  others  the  grinding  is  much  finer.  At  a  recently  installed 

124 


HYD  RATED   LIME:  ITS  PREPARATION  AND,  PROPERTIES.        125 


plant  using  the  Dodge  process,  the  quicklime  passes  first  through  a 
small  crusher,  which  reduces  it  to  about  \  inch.  The  product  is  then 
fed  to  Sturtevant  rock-emery  mills,  which  reduce  it  so  that  about  80  per 
cent  will  pass  a  50-mesh  sieve. 

A  new  rotary  fine  crusher,  devised  by  the  Sturtevant  Mill  Company, 
has  also  been  used  for  crushing  hydrated  lime  to  J  inch  or  so.  The  fol- 
lowing details  regarding  this  crusher  are  taken  from  a  recent  catalogue. 

TABLE  43. 
SIZES,  CAPACITY,  ETC.,  OF  STURTEVANT  CRUSHER. 


Num- 
ber. 

Hopper 
Opening, 
Inches. 

Approxi- 
mate 
Capacity, 
Tons  per 
Hour. 

Approxi- 
mate 
Horse- 
power. 

Speed, 
Revolu- 
tions. 

Pulley 
Diam- 
eter, 
Face. 

Approxi- 
mate 

Weight, 
Pounds. 

Length. 

Width. 

Height. 

1 

13X18 

2  to    6 

6  to  10 

300 

24  X   8 

4000 

V     6" 

3'     1" 

5'     8" 

2 

20X30 

8  to  15 

15  to  20 

250 

32X12 

7500 

8,     2,, 

4'     2" 

6'  10" 

Mixing  with  water. — The  next  step  is  the  actual  slaking,  and  here 
considerable  differences  of  practice  appear,  depending  partly  on  what 
particular  patented  process  is  followed.  The  mixing  is  commonly 

Lime  enters  this  floor 


Grinder  or  Belting  Reel 
or.  Air  Separator 


Crusher  Bin  and  Tank 
to  be  supported  securely 


FIG.  24. — Ellis  lime-hydrating  system. 

carried  on  in  a  pan  with  agitators,  similar  to  a  familiar  form  of  con- 
crete mixer,  or  in  a  horizontal  cylinder.     All  the  lime  may  be  added 


126 


CEMENTS,  LIMES,  AND   PLASTERS. 


to  the  water  at  once,  or  part  may  first  be  mixed  with  an  excess  of  water 
and  then  the  remainder  of  the  lime  added.  In  the  well-known  Dodge 
process  the  first  plan  is  followed.  In  the  Eldred  process  (U.  S.  Patent 
721,871),  in  which  the  second  plan  is  followed,  the  average  amount  of 
lime  handled  at  O'ie  slaking  is  half  a  ton  (1000  Ibs.).  Of  this  amount 
about  400  Ibs.  is  first  mixed  and  slaked  with  450  to  500  Ibs.  water, 
and  then  the  remaining  600  Ibs.  of  quicklime  is  added  to  the  resulting 
paste.  A  slaking-pan  of  the  Walker  &  Elliott  type  is  used. 

The  Campbell  hydrater,  shown  in  Fig.  25,  has  been  successfully  used 
at  several  lime-hydrating  plants.  The  following  data  on  its  size,  capacity, 
power,  etc.,  are  taken  from  a  recent  catalogue  of  the  Clyde  Iron  Works. 

TABLE  44. 
CAPACITY,  POWER,  ETC.,  OF  CAMPBELL  LIME-HYDRATER. 


No. 

Diameter 
of  Pan. 

Height 
of  Pan. 

Capacity 
per  Batch. 

Pulley. 

Speed, 
R.  P.  M. 

Weight. 

2 

8  ft.     0  in. 

16  in. 

1000  Ibs. 

6X24  in. 

175 

4500  Ibs. 

3 

10  "       6  " 

20   " 

2000     " 

6X24  " 

175 

6800    " 

The  amount  of  water  used  will  vary  with  the  character  of  the  lime. 
If  it  is  a  pure  high-calcium  lime,  more  water  is  added  than  if  it  contains 
any  considerable  percentage  of  either  magnesia  or  clayey  matter.  In 
one  process,  for  example,  55  Ibs.  of  water  is  added  to  each  100  Ibs.  of 
high-calcium  lime,  or  30  Ibs.  water  to  100  Ibs.  magnesian  lime. 

Sieving  the  product. — After  slaking  the  product  is  usually  stored  in 
bins  for  forty-eight  hours  or  so,  after  which  it  is  ready  for  use.  Before 
packing,  however,  the  coarser  particles  are  removed  either  by  screen- 
ing or  through  use  of  an  air  separating  device.  When  screens  are  used, 
a  50-mesh  is  the  common  grade,  the  pitch  of  the  screen  surface  being 
changed  to  obtain  whatever  fineness  is  required.  The  Jeffrey  Columbian 
Separator,  which  has  been  used  for  this  purpose,  is  described  in  the  table 
below. 

TABLE  45, 
DETAILS  OF  JEFFREY  SEPARATOR. 


Number 
of 
Machine. 

Width 
Over  All. 

Length 
Over  All. 

Height 
Over  All. 

Size  of 
Main  Driving 
Pulley. 

Speed  of 
Main  Driving 
Pulley. 

Size  of 
Screening 
Surface. 

0 
2 

7  ft.   3£  in. 
11   "    3i  ' 

6  ft.   Hi  in. 
6  "     Hi   " 

7  ft. 
7  " 

12  in.  X4  in. 
12  "  X4  " 

250  rev. 
250    " 

4  ft.X6  ft. 
8"  X6" 

HYDRATED   LIME:  ITS  PREPARATION  AND  PROPERTIES.       127 


128 


CEMENTS,  LIMES,  AND   PLASTERS. 


STANDARDS  FOR  PACKING,  ETC. — At  a  meeting  of  the  hydrated- 
lime  manufacturers  of  the  United  States,  held  in  July,  1904,  the  fol- 
lowing standards  for  packing  and  selling  the  product  were  adopted.* 

Bags. — A  heavy,  closely  woven  burlap  or  duck  bag,  containing 
100  Ibs.,  20  bags  to  the  ton.  A  paper  bag  containing  40  Ibs.,  50  bags 
to  the  ton. 

Quotations. — All  quotations  are  made  including  the  cost  of  the 
package,  no  bulk  quotations  being  made. 

Returned  sacks. — The  burlap  or  duck  bags  will  be  repurchased  from 
the  customer  at  ten  cents  each  when  returned  to  the  mill  in  good  con- 
dition, freight  prepaid. 

Terms  of  settlement. — A  discount  of  1  per  cent  will  be  allowed  for 
cash  in  ten  days,  the  discount  to  be  taken  on  the  full  price,  including 
the  bags  f.  o.  b.  manufacturer's  plant  or  shipping-point.  Net  cash 
thirty  days. 

COST  OF  EQUIPMENT. — The  following  estimate  of  cost  of  equipment 
etc.,  has  been  furnished  by  Mr.  B.  E.  Eldred:^ 

Product  per  hour 5  tons  10  tons 

Cost  of  plant  and  equipment $8,000  .    $10,000 

Men  required  for  operation 4-5  6-8 

Maximum  power  required 35  H.  P.  50  H.  P. 

Average  power  throughout  day 15     "  20     " 

In  estimating  the  cost  of  lime  hydrating,  it  should  be  recollected  that 
the  product  gains  greatly  in  weight  during  the  process.  A  ton  of  quick- 
lime (2000  Ibs.)  will  give  from  2400  to  2600  Ibs.  hydrated  lime. 

Tests  of  hydrated  lime. — The  following  tests  of  two  kinds  of  hydrated 
lime,  while  made  principally  for  the  purposes  of  comparing  high-calcium 
with  magnesian  limes,  will  serve  to  give  an  idea  of  the  tensile  strength 
of  hydrated  lime  in  general. 

TABLE  46. 
TENSILE  STRENGTH  OF  MAGNESIAN  AND  NON-MAGNESIAN  HYDRATED  LIME. 


Kind  of  Lime. 

4  Weeks. 

8  Weeks. 

3  Months. 

4  Months. 

6  Months. 

Magnesian  lime  
High-calcium  lime  

8    Ibs. 
30f    " 

17    Ibs. 
36f    " 

37$  Ibs. 
39|    " 

51  Ibs. 
39   " 

83    Ibs. 
50£    " 

Engineering  News,  vol.  51.  p.  543.     June  9,  1904. 


The  tests  above  quoted  were  made  by  Mr.  S.  T.  Brigham  on  hydrated 
lime  prepared   by  the  Dodge  process.    The  mortar  in  each  case  was 


*  Engineering  News,  vol.  52   p.  220,  Sept.  8,  1904. 


HYD RATED  LIME:  ITS  PREPARATION  AND  PROPERTIES.       129 

composed  of  two  parts  by  weight  of  sand  to  one  part  of  slaked  lime, 
and  the  results  are  given  in  pounds  per  square  inch. 

Mixture  of  hydrated  lime  and  Portland  cement. — Among  the  most 
interesting  features  of  this  new  product  are  the  results  obtained  by 
mixing  slaked  lime  with  Portland  cement.  This  mixture  has  been 
tested  by  several  experimenters,  and  the  results  of  the  tests  are  quoted 
and  discussed  both  by  Sabin  and  Thompson  in  their  recent  books  on 
cements  and  concretes.  The  addition  of  hydrated  lime  to  a  Portland 
cement  mortar  renders  it  more  plastic  and  easier  to  work.  When  this 
addition  does  not  exceed  10  or  20  per  cent  an  actual  increase  in  tensile 
strength  seems  to  be  shown. 

List  of  references  on  hydrated  lime. 

Brigham,  S.  T.  The  manufacture  and  properties  of  hydrate  of  lime.  En- 
gineering News,  vol.  50,  pp.  177-179.  Aug.  27,  1903. 

Brigham,  S.  T.  Hydrated  lime.  Engineering  News,  vol.  51,  pp.  543.  June 
9,  1904. 

Peppel,  S.  V.  Lime  experiments.  Rock  Products,  voL  3,  p.  1,  p.  17.  April 
May,  1904. 

Warner,  C.  Hydrated  lime.  Engineering  News,  vol.  50,  pp.  320-321.  Oct.  8, 
1903. 

Warner,  C.  Strength  tests  of  mixtures  of  hydrated  lime  and  Portland  cament. 
Engineering  News,  vol.  50,  p.  544.  Dec.  17,  1903. 

Warner,  C.  Standards  adopted  by  manufacturers  of  hydrated  lime.  En- 
gineering News,  vol.  52,  p.  220.  Sept.  8,  1904. 


CHAPTER  x. 

.  V* 

MANUFACTURE  AND  PROPERTIES  OF  LIME-SAND  BRICKS. 

THE  term  lime-sand  brick  will  be  used  in  this  volume  to  cover 
all  bricks  made  by  mixing  sand  or  gravel  with  a  relatively  small  per- 
centage of  slaked  lime,  pressing  the  mixture  into  form  in  a  brick  mold, 
and  drying  and  hardening  the  product,  either  by  sun-heat  or  artificial 
methods.  The  general  process  is  not  in  any  way  patentable,  being 
of  very  ancient  date.  Various  details  of  the  process  may,  however, 
be  covered  by  valid  patents,  such,  for  example,  as  on  the  type  of 
molding-press  used,  on  the  exact  methods  and  appliances  for  drying 
and  hardening,  and  on  various  more  or  less  " secret"  compounds  which 
may  be  added  to  facilitate  hardening  or  to  increase  the  final  strength 
of  the  product. 

Early  history  of  the  industry. — Though  in  the  past  few  years  the 
"invention"  of  lime-sand  brick  has  been  heralded  as  a  new  matter, 
the  general  process  has  been  employed  for  many  years  both  in  America 
and  in  Europe. 

The  following  interesting  contemporary  account  *  of  the  manu- 
facture and  use  of  lime  bricks  in  New  Jersey  in  1855  incidentally  estab- 
lishes the  fact  that  the  industry  had  been  known  near  Philadelphia 
since  1838. 

" Gravel  bricks. — A  new  building  material  has  been  introduced  in 
Cumberland  and  some  of  the  adjoining  counties  which  promises  to 
be  both  cheap  and  durable.  The  common  clean  gravel  and  coarse 
sand  of  the  country  is  mixed  with  one  twelfth  its  measure  of  stone  lime 
and  made  into  bricks.  These  bricks  are  sun-dried  and  then  laid  up 
into  walls.  They  are  cheap,  durable,  and  but  little  affected  by  the 
changes  of  the  seasons. 

"In  making,  the  gravel  is  laid  on  a  common  mortar  bed,  and  the 
lime,  which  is  slaked  and  made  into  a  thin  putty  in  a  lime-trough,  is 
then  run  on  the  gravel  and  the  whole  worked  up  into  mortar.  The 

*  Cook,  G.  W.,  in  Second  Ann.  Rept.  of  the  Geol.  Surv.  of  the  State  of  N.  J. 
for  the  year  1855,  pp.  107-108.  1856. 

130 


MANUFACTURE  AND  PROPERTIES  OF  LIME-SAND  BRICKS.      131 

bricks  are  usually  made  as  large  as  is  convenient  for  handling  and  of 
dimensions  to  suit  the  work  for  which  they  are  intended.  The  molds 
are  made,  several  in  the  same  frame,  as  deep  as  the  thickness  of  the 
brick  and  without  any  bottom;  they  are  set  on  smooth  ground  and 
filled  with  mortar.  This  is  worked  in  a  little  with  the  shovel  and  struck 
off  at  the  top.  In  tensor  fifteen  minutes  the  mortar  will  have  set,  so 
that  the  molds  can  be  taken  off.  The  bricks  are  soon  dry  enough  to 
handle,  when  they  can  be  piled  up  and  allowed  to  dry  thoroughly. 
They  are  laid  in  mortar  similar  to  that  from  which  the  bricks  are  made, 
and  the  outside  of  the  buildings  are  roughcast  with  the  same. 

"  Several  buildings  of  this  kind  have  been  erected  in  Eridgeton 
and  its  vicinity  within  the  last  eight  or  ten  years,  and  in  Norristown, 
Pa.,  it  has  been  in  use  for  seventeen  years  past.  It  has  stood  well, 
growing  harder  and  more  solid  every  year.  The  bricks  have  come 
to  be  a  regular  article  of  manufacture  in  several  places.  Those  of 
12"  X  9"  X  6"  were  selling  in  Bridgeton  last  summer  for  $20  a  thousand, 
and  they  could  be  laid,  and  mortar  found,  for  $10  a  thousand,  which 
is  less  than  half  the  cost  of  the  same  measure  of  red-brick  wall.  The 
material  of  which  these  bricks  are  made  being  found  almost  everywhere, 
and  the  labor  of  making  and  laying  them  up  being  very  simple,  farmers 
and  others  who  have  control  of  labor  can  make  and  lay  them  at  times 
when  the  expense  of  the  work  would  not  be  felt,  and  thus  a  saving  much 
greater  than  that  mentioned  could  be  made.  When  first  laid  up  they 
are  not  quite  as  strong  as  other  bricks,  and  greater  care  is  necessary 
in  making  a  solid  foundation,  otherwise  unequal  settling  and  cracks 
in  the  walls  will  result.  Care  must  be  taken  to  make  them  so  early 
in  the  season  as  to  be  entirely  clry  before  the  winter's  frost." 

It  will  be  seen  that  the  general  process  of  lime-sand  brick  manu- 
facture is  well  covered  by  the  above  description,  and  that  both  the 
merits  and  defects  of  the  product  are  stated  rather  more  frankly  than 
is  the  practice  among  its  advocates  to-day.  It  is  to  be  kept  in  mind, 
however,  that  the  lime-sand  brick  manufacturers  to-day  claim  that 
their  product  derives  its  hardness,  not  from  a  simple  recarbonation 
of  the  lime,  but  from  a  more  or  less  thorough  combination  of  the  lime 
with  the  silica  of  the  sand  or  gravel.  As  this  is  a  matter  of  interest 
and  importance,  it  will  be  discussed  in  some  detail  on  a  later  page  (p.  133). 

Whatever  the  value  of  their  contention  may  be,  it  is  evident  that 
even  this  improvement  has  been  anticipated.  That  a  "  lime-silicate  " 
brick  of  modern  type  was  made  about  1850  is  proven  by  the  following 
quotation  of  that  date: 

"  Recent   improvements   in   the   manufacture   of   concrete   building 


132  CEMENTS,  LIMES,  AND  PLASTERS. 

blocks  have  so  far  perfected  the  product  as  to  bring  this  stone  into 
successful  competition  with  the  very  best  of  the  natural  and  artifi- 
cial building  materials.  The  action  of  lime  upon  silica,  forming  a 
silicate  of  lime  (calcmakit),  and  thus  binding  together  particles  of 
sand,  as  in  mortar,  has  been  known  from  the  remotest  ages,  and  con- 
crete walls  of  great  antiquity  are  now  standing,*  vying  with  the  natural 
rock  in  hardness  and  durability.  Some*  years  since  a  concrete  block, 
compacted  by  pressure,  was  brought  out  in  this  country  and  used  to 
some  extent  as  a  building  material,  but  the  slowness  of  the  induration 
and  uncertainty  in  the  product  hindered  its  general  introduction. 
The  improvements  referred  to  consist  in  the  use  of  heat  in  connection 
with  quicklime  and  sand,  by  which  the  formation  of  the  silicate  of  lime 
is  hastened,  and  the  same  effect,  which  formerly  took  years  to  be  con- 
summated, is  now  produced  in  a  few  days.  Ground  quicklime  is  thor- 
oughly mixed  with  clean,  sharp  sand,  and  is  then  subjected  to  the  action 
of  either  superheated  or  high-pressure  steam,  which  slaks  the  lime 
and  causes  it  to  attack  the  silica.  This  process  continues  for  from 
twenty  minutes  to  ten  days,  according  to  the  degree  of  heat  employed, 
when  the  material  is  molded  and  compressed  by  a  heavy  steam-ham- 
mer into  blocks  of  any  desired  form.  The  ordinary  building-block 
made  by  this  process  is  10  inches  wide  and  4  inches  deep,  having  a 
hollow  space  in  the  center  6  inches  long  by  1  inch  broad;  when  the 
blocks  are  placed  upon  each  other,  so  as  to  break  joints,  a  continuous 
and  connected  series  of  air-chambers  will  be  formed  within  the  wall. 
Thirty  days'  exposure  of  the  block,  after  it  is  first  formed,  to  the  air, 
produces  an  induration  quite  sufficient  for  all  ordinary  building  pur- 
poses, but  the  block  continues  to  harden  for  an  unlimited  period.  A 
church  built  entirely  of  this  material  was  recently  dedicated  at  Morris- 
ania.  A  number  of  fine  buildings  have  already  been  constructed  of 
this  material  in  Chicago,  among  which  may  be  mentioned  a  handsome 
block  of  dwellings  on  Sixteenth  Street,  and  the  Young  Men's  Christian 
Association  of  the  same  city,  which  was  recently  burned.  The  endur- 
ance of  this  stone  when  submitted  to  repeated  freezing  and  thawing 
is  quite  remarkable,  and  experiment  proves  it  to  be  equal  in  this  respect 
to  granite." 

The  theory  of  lime-sand  brick. — When  ordinary  quicklime  is  slaked, 
mixed  with  sand,  and  used  as  mortar  the  mixture  hardens  very  slowly 
and  never  attains  much  strength.  The  hardening  is  due  to  the  fact 
that  the  slaked  lime  gradually  absorbs  carbon  dioxide  from  the  atmos- 
phere and  recarbonates,  forming  a  sort  of  artificial  limestone.  So 
far  as  known,  there  is  no  chemical  action  between  the  lime  and  the 


MANUFACTURE  AND  PROPERTIES   OF  LIME-SAND  BRICKS.      133 


sand  of  the  mortar,  though  occasionally  the  statement  is  made  that 
with  increasing  age  a  certain  amount  of  chemical  action  does  take  place, 
resulting  in  the  formation  of  a  certain  percentage  of  lime  silicate.  This, 
however,  is  more  than  doubtful. 

In  making  lime-sand  -brick  by  modern  processes,  it  is  claimed  by 
its  advocates  that  the  lime  and  sand  of  the  brick  do  combine  to  form 
lime  silicates,  the  combination  being  in  this  case  brought  about 
through  the  action  of  steam  under  high  pressure.  It  is  also  claimed, 
though  rather  by  suggestion  than  by  direct  statement,  that  these  lime 
silicates  make  up  a  considerable  proportion  of  the  entire  mass  of  the 
brick. 

To  the  present  writer  the  first  claim  does  not  seem  to  be  justified. 
No  proofs  have  been  presented  that,  in  the  course  of  lime-sand  brick 
manufacture,  any  chemical  combination  takes  place  between  the  lime 
and  the  sand.  It  is  undoubtedly  true  that  the  treatment  with  steam 
under  pressure  increases  in  some  unexplained  way  the  chemical  activity 
of  the  slaked  lime;  but  further  than  that  we  cannot  go  at  present. 

The  second  point,  regarding  the  percentage  of  lime  silicate  which 
would  be  formed  if  chemical  combination  of  lime  and  silica  took  place, 
can  be  readily  settled.  The  lime  and  silica  might  unite  in  any  one  of 
three  proportions,  forming  respectively  the  calcic  silicate  (CaO.SiC^), 
the  dicalcic  silicate  (2CaO.SiO2),  or  the  tricalcic  silicate  (3CaO.SiO2). 
The  last  of  these  is  the  one  which  is  formed  during  the  processes  of 
manufacture  of  Portland  cement,  and  is  the  hydraulic  silicate  par  ex- 
cellence. In  most  sand-lime  brick  literature  a  similarity  between  that 
product  and  Portland  cement  is  suggested,  even  if  not  definitely  claimed. 
In  the  little  table  below  the  percentage  composition  of  these  three  lime 
silicates  is  presented.  It  will  be  seen  that  the  tricalcic  silicate  contains 
73.59  per  cent  lime  to  26.41  per  cent  silica,  while  the  proportion  of 
lime  decreases  until  it  reaches  51.84  per  cent  in  the  unicalcic  silicate. 

TABLE  47. 
PERCENTAGE  COMPOSITION  OF  VARIOUS  LIME  SILICATES. 


Compound. 

Per  Cent 
CaO. 

Per  Cent 
SiO2. 

CaO.SiO2. 

51   84 

48  16 

2CaO.Si02  
3CaO.SiO2.  .... 

65.01 
73.59 

34.99 
26.41 

The  bearing  of  these  facts  upon  lime-sand  brick  manufacture  is  obvious 
enough. 


134 


CEMENTS,  LIMES,  AND  PLASTERS 


The  amount  of  slaked  lime  used  in  making  lime-sand  brick  will 
amount  to  5  to  10  per  cent  of  the  whole  mass,  averaging  about  8  per 
cent.  If  all  of  this  8  per  cent  of  lime  be  combined  with  silica  in  the 
richest  possible  silicate  (CaO.SiC^),  it  will  take  up  only  7  percent  of 
sand.  So  that  on  the  most  hopeful  possible  basis  only  15  per  cent 
of  the  brick  would  have  any  binding  properties,  the  remainder  being 
merely  uncombined  and  inert  sand.  ^ 

General  processss  of  lime-sand  brick  manufacture. — The  general 
processes  involved  in  the  manufacture  of  lime-sand  brick  are,  in  order, 
as  follows: 

a.  Slaking  the  lime. 

6.  Mixing  the  lime  and  sand. 

c.  Pressing  the  mixture  into  molds. 

d.  Hardening  the  brick. 

Necessary  properties  of  the  sand. — All  the  sand  should  pass  a  20-mesh 
screen,  and  it  is  desirable  that  part  of  it  (say  10  per  cent)  should  be 
fine  enough  to  pass  a  150-mesh  screen.  Clayey  material  in  the  sand  is 
detrimental  to  the  strength  of  the  brick  made  from  it.  The  compo- 
sition of  the  sand  grains  themselves  probably  has  little  influence  on  the 
strength  of  the  resulting  brick;  but  in  order  to  secure  a  light  and  uni- 
form color  it  is  desirable  that  the  sand  should  consist  almost  entirely 
of  grains  of  quartz  and  that  the  dark  silicate  minerals  (hornblende, 
garnet,  mica,  etc.)  should  be  present  in  no  great  quantity. 

In  testing  the  influence  of  size  of  sand,  Peppel  *  used  mixtures  in 
various  proportions  of  two  sands.  These  gave  the  following  results 
on  sieving: 


Coarse  Sand. 

Fine  Sand. 

20-  t 
40- 
60- 
80- 
100- 
120- 
150- 
Passii 

o    40-m< 
60- 
80- 
100- 
120- 
150- 
200- 
ig  200-m 

ash  

50  per  ce 
33    " 

7    " 
7    " 
2    " 
1    " 

nt 

Tff  per  cent 

H    "      " 
93^"      " 



esh  

The  coarse  sand  was  a  very  pure  sharp  glass  sand;  the  fine  sand 
was  crushed  quartz.  Made  up  into  bricks  with  5  per  cent  of  lime  the 
results  shown  in  the  following  table  were  obtained. 


*  Tra.ns.  Amer.  Ceramic  Soc.,  vol.  5.     Page  4  of  pamphlet  edition. 


MANUFACTURE  AND   PROPERTIES  OF  LIME-SAND   BRICKS      135 


TABLE  48. 
EFFECT  OF  FINENESS  OF  SAND.     (PEPPEL.) 


Composition  of  Sand  Mixture 
by  Paris. 

Crushing 
Strength, 
Pounds  per 
Square  Inch. 

Tensile 
Strength, 
Pounds  per 
Square   Inch. 

Coarse. 

Fine. 

8 
4 

3 

2 
2 
2 

3114 
2955 
2461 

131 
144 
224 

These  tests  show  that  the  bricks  decrease  in  compressiye  strength 
and  increase  in  tensile  strength  as  the  amount  of  fine  sand  in  the  mix- 
ture increases.  These  results  of  themselves  appear  to  be  unfavorable 
to  the  contention  of  lime-sand  brick  manufacturers,  that  the  strength 
of  their  product  is  due  to  chemical  reactions  between  the  sand  and  the 
lime.  For  if  this  contention-  were  true,  the  finer  sand  particles  would 
certainly  be  more  active  chemically  than  the  coarser  grains,  and  an 
increase  in  fineness  of  sand  would  necessarily  mean  more  extensive 
chemical  inte  action  and  consequently  greater  strength  in  both  com- 
pression and  tension. 

Drying  the  sand. — In  order  to  secure  uniformity  in  the  product 
it  is  desirable  that  the  sand  should  be  dried  before  mixing  with  the 
lime.  So  far  this  point  has  not  been  realized  by  many  manufacturers, 
who  are  content  to  use  the  sand  as  it  comes  from  the  pit — at  one  time 
practically  dry,  at  another  carrying  10  to  15  per  cent  of  moisture. 

As  to  methods  of  sand-drying,  considerable  differences  in  practice 
exist.  In  the  Schwarz  machine,  described  and  figured  on  page  137, 
the  sand  is  placed  in  a  steam-jacketed  drum,  the  drying  being  aided 
by  revolving  paddles  which  stir  up  the  sand.  At  a  number  of  plants 
live  or  exhaust  steam  is  used  in  pipe-dryers,  the  sand  being  shoveled 
on  a  series  of  horizontal  pipes  filled  with  steam.  The  best  practice  is 
probably  to  use  a  rotary  dryer.  At  one  plant  *  a  direct-heat  rotary 
dryer  22  inches  in  diameter  and  22  feet  long,  set  at  a  slope  of  about 
}  inch  to  the  foot,  dries  40  to  50  yards  of  sand  in  ten  hours  with  a  fuel 
consumption  of  700  Ibs.  coal.  At  another,  a  30-foot  dryer  set  at  a  slope 
of  about  J  inch  per  foot,  with  a  fan  to  induce  draft,  is  handling  40  to 
50  yards  sand  in  ten  hours  with  a  consumption  of  600  to  800  Ibs.  coal. 

Necessary  properties  of  the  lime. — The  lime  should  be  carefully 
and  thoroughly  slaked,  and  should  be  as  free  from  impurities  as  possible. 
The  presence  of  more  than  a  few  per  cent  of  clayey  matter  or  iron  oxide 

*  The  Clay  Worker,  vol.  42,  p.  588.     1904. 


136 


CEMENTS,  LIMES,  AND   PLASTERS. 


is  undesirable,  not  so  much  because  of  its  effect  on  the  strength  or  dura- 
bility of  the  brick  as  because  of  its  effect  on  the  color. 

The  following  experiments  on  high-calcium  vs.  magnesian  limes 
appear  to  prove  that  the  latter  give  bricks  inferior  in  strength.  In  view 
of  the  results  attained  elsewhere,  however,  those  in  the  table  below 
should  be  accepted  with  caution. 

TABLE  49r* 

COMPARATIVE  TESTS  OF  HIGH-CALCIUM  AND  MAGNESIAN  LIME 
BRICKS.    (PEPPEL.) 


Lime  Used. 

Amount. 

Tests  of  Strength. 

Per  Cent 
of  Water 
Absorbed. 

After  Hardening. 

After  Freezing. 

Compres- 
sion, 
Pounds  per 
Square 
Inch. 

Tension, 
Pounds  per 
Souare 
Inchv 

Compres- 
sion, 
Pounds  per 
Square 
Inch. 

Tension, 
Pounds  per 
Square 
Inch. 

7745 

5187 

437 

286 

9007 

5853 

371 
314 

8.62 

9.11 

Trans.  Amer.  Ceramic  Soc.,  vol.  5.     Page  15  of  pamphlet  edition. 

The  lime-sand  bricks  whose  results  are  shown  in  the  above  table 
were  made  up  of  two  parts  coarse  sand  and  one  part  fine  sand,  to  which 
base  was  added  10  per  cent  of  lime.  The  blocks  were  molded  under 
a  pressure  of  15,000  Ibs.  per  square  inch  and  hardened  by  exposure 
for  four  to  fourteen  hours  to  a  steam  pressure  of  150  Ibs.  per  square 
inch  at  a  temperature  of  185°  C.  Each  of  .the  results  given  in  the  table 
is  the  average  of  twelve  tests. 

Methods  of  slaking  the  lime. — The  lime  may  be  either  slaked  to  a 
paste  by  the  addition  of  more  water  than  is  theoretically  required 
or  slaked  to  a  dry  powder.  The  general  methods  employed  are  usually 
similar  to  those  in  the  lime-hydrate  industry.  In  one  process,  however, 
a  machine  of  entirely  different  type  is  employed,  which  requires  some 
notice. 

The  Schwarz  process  is  described  *  as  follows: 

"  The  first  operation  in  the  Schwarz  process  is  the  mixing  of  the 
sand  and  lime,  which  is  done  in  a  vacuum  mixing-machine.  This 
machine  is  shown  in  transverse  and  longitudinal  section  in  Fig.  26. 
Briefly  described,  the  machine  consists  of  a  steam- jacketed  drum  with 
interior  rotary  blades  operated  by  suitable  gearing  outside  and  at  one 
end.  This  drum,  which  has  a  capacity  of  about  three  tons  of  sand, 


*  Engineering  News,  vol.  49,  p.  179.     Feb.  19,  1903, 


MANUFACTURE  AND  PROPERTIES  OF  LIME-SAND  BRICKS.      137 

is  filled  by  means  of  a  funnel  placed  above  it.  When  the  drum  is 
charged,  the  interior  mixing-blades  are  set  in  motion  and  the  contents 
are  heated  by  means  of  the  steam-jacket  surrounding  the  drum.  A 
vacuum  pump  attached  to  the  apparatus  removes  the  steam  and  air 
from  the  drum.  When  the  sand  has  been  properly  dried  the  required 
quantity  of  finely  pulverized  lime  is  introduced  into  the  drum  through 


CROSS  SECTION  A-B 

FIG.  26. — Schwarz  drying-  and  mixing-machine. 

•a  special  aperture  and  the  mixture  is  again  stirred  and  heated.  The 
necessary  quantity  of  moisture  is  then  introduced  into  the  drum  in 
the  form  of  water  or  steam  by  means  of  a  pipe  penetrating  the  interior 
of  the  drum.  After  wetting,  the  mixture  continues  to  be  stirred  and 
heated  during  a  sufficient  time  to  allow  a  preliminary  combination  of 
the  lime  and  sand  to  take  place  and  produce  a  mixture  with  sufficient 
tenacity  to  permit  of  easy  molding." 


138 


CEMENTS,  LIMES,  AND  PLASTERS. 


Proportions  of  mixture. — The  slaked  lime  is  mixed  with  sand  in 
the  usual  proportion  of  5  to  10  Ibs.  of  lime  to  100  Ibs.  of  sand.  Peppel 
experimented  on  this  point  by  preparing  mixtures  carrying  various  pro- 
portions of  lime  and  sand.  His  results  are  shown  in  the  following  table. 

TABLE  50. 
EFFECT  OF  PERCENTAGE  OF  LIME.      (PEPPEL.) 


Composition  of  Mixture. 

f*  Strength  in  Pounds  per  Square  Inch. 

Coarse 
Sand. 

Fine 
Sand. 

Lime. 

After 
Hardening. 

After 

Aging. 
^ 

After 
Freezing. 

Com- 
pres- 
sion. 

Ten- 
sion. 

Com- 
pres- 
sion. 

Ten- 
sion. 

Com- 
pres- 
sion. 

Ten- 
sion. 

60  Ibs. 
60    " 
60    " 
60    " 

40  Ibs. 

4Q     " 
40    " 
40    " 

5  Ibs.  magnesian  lime.  .  . 
10    "            "            "    ... 
5  Ibs.  high-calcium  lime 
40    " 

3697 
5607 
2636 
7018 

427 
503 
194 
541 

3812 

7525 
7995 

417 
516 

5843 
7153 

446 

622 

Trans.  Amer.  Chem.  Soc.,  vol.  5.     Page  13  of  pamphlet  edition. 

The  mixture  may  be  accomplished  in  pug-mills,  edge-runner  mills,, 
wet  pans  or  dry  pans. 

Methods  of  molding. — The  mixture  is  shaped  into  bricks  in  a  press. 
Peppel  states  *  that  a  press  should  fulfil  the  following  requirements: 

"(1)  The  press  must  be  able  to  regularly  deliver  a  pressure  of  from 
200  to  250  tons  per  brick  and  yet  not  break  down  if  by  accident  the 
pressure  rises  somewhat  higher. 

"  (2)  The  filling  of  the  mold  must  be  accomplished  with  great  ac- 
curacy and  uniformity. 

"  (3)  All  working  parts  must  be  so  arranged  that  they  will  be  free  from 
contact  with  loose  sand,  otherwise  they  will  cut  out  at  an  alarming  rate. 

"  (4)  The  dies  and  mold  linings  must  be  made  of  the  hardest  mate- 
rial obtainable." 

Many  presses,  both  of  American  and  German  design,  are  now  on  the 
market  for  use  in  the  lime-sand  brick  industry.  Any  machine  that  will 
press  clay  brick  has  power  and  strength  enough  to  handle  lime-sand 
brick,  but  the  new  product  is  so  fragile  as  to  require  delicate  handling 
in  taking  off  the  press. 

Methods  of  hardening  the  bricks. — Three  general  types  of  harden- 
ing processes  have  been  in  use.  These  are:  (1)  hardening  by  simple 
exposure  to  the  atmosphere;  (2)  hardening  in  an  atmosphere  saturated 
with  carbon  dioxide;  (3)  hardening  in  a  cylinder  filled  with  steam 
under  pressure. 

*  Trans.  American  Ceramic  Society,  vol.  5,  pp.  33-35  of  pamphlet  Edition. 


MANUFACTURE  AND   PROPERTIES  OF  LIME-SAND   BRICKS.      139 


The  first  of  these  processes  is  slow,  since  the  hardening  takes  place 
only  as  rapidly  as  the  lime  in  the  brick  can  absorb  water  and  carbon 
dioxide  from  the  atmosphere.  The  second  process  is  more  rapid,  but 
the  change  of  slaked  lime  to  lime  carbonate  is  still  incomplete.  In 
the  third  process,  which  is  the  one  used  at  practically  all  lime-sand 
brick  plants  to-day,  the  reactions  are  rapid,  and  its  advocates  claim 
in  addition  that  the  steam  under  pressure  causes  the  combination  o 
the  lime  with  the  sand,  so  as  to  form  a  greater  or  lesser  amount  of  sili- 
cate of  lime.  The  truth  of  this  contention  seems  to  be  more  than  ques- 
tionable; but  the  process  is  in  increasing  use  and  therefore  demands 
a  somewhat  more  detailed  description. 

In  the  process  as  now  followed,  the  bricks  are  loaded  onto  trucks 
and  these  are  run  into  a  long  horizontal  cylinder.  This  hardening 
cylinder  is  then  closed  and  steam  under  pressure  is  admitted. 

The  experiments,  whose  results  are  given  in  table,  were  undertaken 
by  S.  V.  Peppel  to  determine  the  most  advantageous  steam  pressure 
and  time  of  hardening.  In  discussing  these  results,  Peppel  states  that 
"this  table  shows  that  four  hours'  time  at  150  Ibs.  steam  pressure  is 
sufficient;  that  six  or  eight  hours  are  required  at  120  Ibs.;  that  eight 
to  twelve  hours  are  required  at  100  Ibs. " 

To  the  present  writer,  however,  the  table  seems  to  show  that  very 
little  relation  of  any  kind  exists  between  pressure  and  time  and  the 
strength  of  the  resulting  brick. 


TABLE  51. 

EFFECTS  OF  STEAM  PRESSURE  AND  TIME  OF  HARDENING. 
Strength  in  pounds  per  square  inch. 


(PEPPEL.) 


Is-s 

I:; 

00 

A 

B 

C 

i 

I 

). 

E 

*§! 
pi 

OQ 

Hours  in 

Com- 
pres- 
sion. 

Ten- 
sion. 

Com- 
pres- 
sion. 

Ten- 
sion. 

Com- 
pres- 
sion. 

Ten- 
sion. 

Com- 
pres- 
sion. 

Ten- 
sion. 

Com- 
pres- 
sion. 

Ten- 
sion. 

150 
150 
150 
150 
150 
150 
120 

4 
6 

8 
10 
12 
14 
4 

7896 
7994 
7404 
7767 
7514 
7894 
6989 

544 
390 
509 
464 
337 
380 

5303 
5045 
4957 
4902 
5064 
5849 
5989 

392 

199 
262 
284 
250 
329 

5282 
6170 
6165 
5403 

591 
632 
556 

4514 
4249 
4543 
4300 

470 
430 
434 

4441 
4491 
4924 
5760 

330 
337 
349 

120 

6 

7063 

6495 

120 

8 

8545 

6038 

5868 

5142 

6718 

100 

4 

6385 

5921 

4280 

4048 

4588 

100 

6 

7566 

6507 

5564' 

4456 

6544 

100 

8 

7494 



5753 

Trans.  Amer.  Ceramic  Soc.,  vol.  5.     Page  25  of  pamphlet  edition. 


140  CEMENTS,  LIMES,  AND  PLASTERS. 

The  hardening  cylinder,  according  to  Peppel,  should  be  constructed 
of  f  to  |  inch  iron  or  steel  plate.  The  cylinder  is  bricked  in  to  prevent 
radiation  and  has  one  removable  end  or  head.  This  head  "should 
be  handled  by  an  overhead  crane  or  a  block  and  tackle.  Hinged  doors 
with  a  wheel  on  the  bottom  and  a  track  for  the  wheel  to  run  on  have 
been  used.  These  are  clumsy  affairs  to  move  and  occupy  much 
space,  and  should  never  be  .recommended.  The  bolts  should  be  so 
fastened  to  the  cylinder  that  the  head  can  readily  be  swung  into  place. 
These  bolts  are  usually  1J  to  1^  inches  in  diameter".  The  cylinder 
varies  in  length  from  35  to  67  feet,  and  in  diameter  from  5^  to  7  feet. 

Costs  of  plant  and  manufacture. — The  following  estimates  of  cost 
of  plant  and  production  are  given  by  Peppel :  * 

COST  OF  PLANT  FOR  40,000  BRICK  PER  DAY.     (PEPPEL.) 

Land  and  buildings $15,000 

1  wet-pan 1,000 

1  ball-mill '.         500 

2  presses 4,400 

2  pug-mills 800 

Conveyors 6,000 

Shafting  and  belting 3,000 

1  100-H.P.  Corliss  engine 2,500 

2  100-H.P.  boilers 2,000 

1    25-H.P.  boiler 300 

4  hardening-cylinders  7'  X  60'.  . . . '. 8,000 

Erecting  and  insulating  cylinders 1,000 

Pipes  for  preliminary  heating 1,000 

Railroad  tracks,  etc 4,500 

$50,000 
COST  OF  MANUFACTURE,  40,000  BRICK.     (PEPPEL.) 

Sand:  157  cubic  yards  at  $0 .07 $11 .00 

Lime:  11  tons  at  $4.00 44.00 

Coal:     3  tons  at  $2.25 6.75 

Repairs 5 . 00 

Oil  and  grease 3 .00 

Labor:  40  men  at  $1.35 54.00 

Foreman  at  $2.50 2 . 50 

Office  expenses 20 . 00 

Depreciation  and  interest,  12  per  cent 20 . 00  ' 

£166.25 
Selling  expenses,  10  per  cent 16 .00 

$182.25 
Cost  of  brick  per  thousand $4 . 55 

*  Trans.  Amer.  Ceramic  Soc.,  vol.  4. 


MANUFACTURE  AND   PROPERTIES  OF  LIME-SAND  BRICKS.      141 

With  these  estimates  may  be  compared  the  following  data  on  costs 
of  production,  gathered  from  various  sources: 

The  Huennekes  Company,  in  advertising  their  system  of  lime-sand 
brick  manufacture,  state  that  an  output  of  20,000  brick  per  day  of 
twenty-four  hours  will  require 

c    1  engineer 
Labor:      -j    1  fireman 
(.   8  laborers 

{3  tons  coal 
2J  tons  lime 
50  tons  sand 

At  a  small  plant  using  another  system  recently  visited  by  the  writer, 
six  men  operated  the  mill,  exclusive  of  superintendence.  They  were 
distributed  as  follows :  two  digging  and  handling  sand,  one  at  the  mixer, 
two  at  the  press,  and  one  at  the  engine.  A  30-H.P.  engine  sufficed  to- 
run  two  pan-mixers,  two  screw-mixers,  one  elevator,  and  one  brick- 
press,  and  gave  a  product  of  10,000  brick  per  day  of  twenty-four  hours. 
Sand-beds  occur  near  the  plant,  but  lime  is  expensive,  being  bought  in 
the  hydrate  form  and  carried  by  rail  for  over  400  miles.  Coal  is  also- 
expensive.  Neither  labor  nor  machinery  is  particularly  efficient,  and 
repairs  and  supplies  must  therefore  be  allowed  for  at  rather  a  high  figure. 
The  finished  brick  are  not  of  very  good  grade,  but  can  be  sold  in  absence 
of  competition 'from  a  really  good  clay  brick  at  $8.00  to  $9.00  per- 
thousand. 

The  following  is  probably  a  fair  estimate  of  the  cost  of  manu- 
facturing lime-sand  brick  at  this  plant: 

Lime,  1£  tons  at  $8 . 00  per  ton $12 . 00 

Coal,  1  £  tons  at  $4 . 25  per  ton 6 . 38 

Labor,  6  men 8 . 75 

Superintendence  and  office  expenses 10.00 

Repairs,  supplies,  etc 2 .00 

Interest,  depreciation,  etc 6.00 

Cost  per  10,000  brick $45. 13 

Cost  per  thousand 4 . 51 

At  a  recent  convention  *  of  sand-lime  brick  manufacturers,  several 
partial  estimates  of  cost  of  manufacture  were  submitted.  One  esti- 
mate put  the  total  cost  of  manufacture  at  $5.00  per  thousand  brick, 
allowing  for  coal  at  $4.25  per  ton,  lime  at  80  cents  per  barrel,  and  sand 
at  60  cents  per  yard.  Another  placed  the  total  cost  at  $3.60  per  thou- 
sand, with  slack  coal  at  $1.45  per  ton  and  lime  at  40  cents  per  barrel. 

*  Proceedings  of  the  1st  Annual  Convention,  National  Assoc.  Mfrs.  Sand-Lime 
Products,  reported  in  the  "Clay  Worker",  vol.  42,  pp.  582-591.     Dec.  1904. 


142 


CEMENTS,  LIMES,  AND  PLASTERS. 


A  third,  slightly  more  detailed,  gave  the  following  figures  for  a  plant 

of  15.000  capacity. 

Sand  and  lime $1.10 

Labor 1-75 

Fuel  and  repairs 0-50 

Fixed  charges !  •  °0 

Total  cost  per  thous.and $4 . 35 

Composition  of  lime-sand  bricks.— Lime-sand  bricks  will  usually 
range  in  composition  between  the  following  limits: 

Silica  (SiO2),  alumina  (A12O3),  and  iron  oxide  (Fe2O3) .  .   85^-95  per  cent 

Lime  (CaO)  and  magnesia  (MgO) 9-3 

Water 6-2    "      « 

The  bulk  composition  of  the  product  is  therefore  a  fairly  definite 
matter  and  not  subject  to  discussion.  The  point  concerning  which 
there  is  a  definite  disagreement  is  as  to  the  manner  in  which  the  above 
constituents  are  combined  in  the  brick.  The  more  ardent  advocates 
of  lime-sand  brick  claim  that  most  of  the  lime  is  combined  with  part 
of  the  silica  as  a  calcium  silicate,  and  support  this  contention  by  pre_ 
senting  analyses  showing  the  presence  of  noticeable  percentages  of 
soluble  silica.  In  the  .opinion  of  the  present  writer  this  contention  is 
not  proven.  All  that  we  know  concerning  the  character  and  formation 
of  the  various  silicates  of  lime  seems  to  point  in  the  opposite  direction. 
So  far  as  known  no  lime  silicate  can  be  formed  except  at  Very  high  tem- 
peratures, 900°  C.  or  thereabouts. 

Physical  properties  of  lime-sand  bricks. — Lime-sand  bricks  are 
sufficiently  strong,  when  subjected  to  direct  compressive  strains,  for 
all  ordinary  structural  purposes.  Many  of  them,  however,  are  very 
fragile  and  require  careful  handling  both  in  transportation  and  on 
the  work. 

The  following  comparison  has  been  made  *  by  Peppel  between 
lime-sand  bricks  and  a  series  of  natural  sandstones  tested  by  the  Wis- 
consin Geological  Survey. 

TABLE  52. 
LIME-SAND  BRICKS  vs.  NATURAL  SANDSTONE.     (PEPPEL.) 


Lime-sand 
Bricks. 

Natural 
Sandstone. 

Weight  per  cubic  foot  

136  Ibs. 
8  per  cent 
7745  Ibs. 
600,000 

137  Ibs. 
7.3  per  cent 
6535  Ibs. 
165,440 

Absorption            

Crushing  strength  per  sq.  in.  ... 
Coefficient  of  elasticity 

*  Trans.  Amer.  Ceramic  Society,  vol.  5,  p.  31  of  pamphlet  edition. 


MANUFACTURE  AND   PROPERTIES  OF  LIME-SAND   BRICKS.     143 


The  following  series  of  tests  show  much  lower  compressive  strength 
and  higher  absorption  than  those  above  quoted. 

The  tests  summarized  in  the  following  table  were  made  in  1901 
on  lime-sand  bricks  made  on  the  Huennekes  system. 

TABLE  53. 
PHYSICAL  TESTS  OF  LIME-SAND  BRICK.     (PITTSBURG  TESTING  LABORATORY.) 


Crushing 
Strength  per 
Square  Inch. 

Absorption 
Test  45  Hours 
in  Water. 
Per  Cent  Gain. 

Absorption 
after  Freezing 
Test. 
Per  Cent  Gain. 

Crushing 
Strength  per 
Square  Inch 
after  Freezing. 

3518  Ibs. 
4162     " 

3859     '  ' 

11.6 

8.57 
11.3 

12.4 

8.8 
11.4 

4137  Ibs. 
5202    " 

In  making  the  absorption  tests  half  bricks  were  used,  which  were 
dried  thoroughly  before  being  immersed  in  water.  After  remaining 
in  water  45  hours,  bricks  were  frozen  4  hours  at  a  temperature  of  14°  F., 
then  thawed  in  warm  water  12  hours,  frozen  again  at  a  temperature  of 
9°  F.  for  a  period  of  3J  hours,  thawed  in  hot  water  3  hours,  frozen  at 
a  temperature  of  12°  F.  for  3J  hours,  and  finally  thawed  in  hot  water 
for  12  hours.  Final  absorption  test  made  and  then  bricks  were  again 
thoroughly  dried.  Bricks  showed  no  signs  of  cracking  or  disintegration. 

Another  series  of  tests  of  brick  made  by  the  Ventnor  Concrete  Co., 
operating  on  the  Huennekes  system,  is  summarized  below. 

TABLE  54. 

TESTS  OF  LIME-SAND  BRICKS.     (U.  S.  NAVAL  ACADEMY.) 
Crushing:  Size  of  cube  2" X 2" X 2&". 

Total. 

No.  1 12,580  Ibs. 

No.  2 16,500    " 

No.  3 10,350    " 

Absorption :  Immersed  72  hours. 


Per  sq.  in. 
3145  Ibs. 
4125  " 
2588  " 


Weight  i 

n  Grains. 

Dry. 

Wet. 

Dif. 

Per  Cent. 

No    1 

1241 

1337 

96 

7.735 

No    2 

1270 

1375 

105 

2.275 

No    3        

1300 

1498 

108 

7.777 

Approximate  size  of  whole  brick 8f"X4£"X2jf" 

Approximate  weight  of  whole  brick 5  Ibs.  14  ounces 

One  whole  brick  and  one  brick  broken  in  four  pieces  were  soaked 
in  warm  water  and  then  put  in  tin  cans  with  sufficient  water  to  cover 


144 


CEMENTS,  LIMES,  AND   PLASTERS. 


them  and  frozen  in  the  open  air,  the  thermometer  ranging  from  4  degrees 
to  20  above  zero.  This  was  repeated  four  times,  thawing  in  warm 
water  each  time.  They  were  then  frozen  in  salt  and  ice  (temperature 
being  above  freezing-point)  three  times.  The  entire  process  did  not 
have  any  bad  results  with  the  whole  brick.  The  pieces  scaled  a  little 
at  the  edges,  probably  due  to  small  pieces  loosened  by  the  breaking  of 
the  brick.  Another  brick  was  -placed  in;  open  air  in  a  freezing  tem- 
perature and  water  allowed  to  drip  and  :freeze  on  it  until  coated  with 
ice  without  any  bad  results. 

Two  specimens  of  lime-sand  brick  (Huennekes  syste.ni)  were  tested 
in  1904  by  Prof.  Marston,  giving  compressive  strengths  respectively 
of  3210  and  2097  Ibs.  per  square  inch,  and  absorptions  of  10.9  and 
11.0  per  cent. 

In  1904  Prof.  Woolson  tested  several  lime-sand  brick  made  on  the 
Schwarz  system,  with  the  following  results. 

TABLE  55. 
COMPRESSION  TESTS,  LIME-SAND  BRICK.     (WOOLSON.) 


(a) 

(b) 

Height   inches 

2  25 

2  40 

"Width   inches 

4  13 

4  15 

Thickness   inches 

4  00 

4  00 

Area  square  inches 

16  52 

16  60 

Maximum  load,  Ibs 

59,340 

60,300 

Ultimate  strength,  Ibs.  per  sq.  in.  .  . 

3,592 

3,633 

In  Table  56  are  given  the  results  of  a  series  of  tests  made  at 
Charlottenburg  on  various  brands  of  lime-sand  brick  made  in  Germany* 
It  will  be  seen  that  these  results  are  very  low. 

TABLE  56. 
PHYSICAL  TESTS  OF  LIME-SAND  BRICKS.     (CHARLOTTENBURG.) 


Crushing  Strength  in  Pounds  per 
Square  Inch. 

Absorption, 
Per  Cent. 

Dry  Brick. 

Water- 
soaked  Brick. 

After 
Freezing. 

1704 
2215 
4189 
1732 
3710 
850 
1353 
1193 

1903 
2073 
3933 
1846 

i335 

2229 
2300 
4260 
2187 
3238 
1335 
1747 
1562 

12.0 
14.0 
9.0 
10.6 

18.3 

Trans.  Amer.  Ceramic  Soc.,  vol.  4. 


MANUFACTURE  AND  PROPERTIES  OF  LIME-SAND  BRICKS.     145 


Summary  of  the  results  of  tests. — The  three  American  series  of 
tests  above  quoted  (Tables  53,  54,  and  55)  were  made  on  samples  of 
brick  furnished  by  the  manufacturers,  and  the  results  of  these  tests 
are  now  used  for  advertising  purposes.  It  seems  fair  to  assume,  there- 
fore, that  these  results  are  not  inferior  to  the  average  run,  but  are, 
on  the  contrary,  probably  better  than  the  usual  American  lime-sand 
brick  as  found  on  the  market. 

The  bricks  tested  at  Charlottenburg,  on  the  other  hand,  were  prob- 
ably selected  from  marketed  products,  and  are  probably  fairly  repre- 
sentative of  the  average  German  product  as  it  reaches  the  building 
trade. 

The  two  sets  of  results  have  therefore  been  averaged  separately, 
with  the  results  given  below. 

TABLE  57. 
SUMMARY  ^LIME-SAND  BRICK  TESTS. 


Strength,  Pounds  per  Sq.  In. 

Absorption,  Per  Cent. 

Max. 

Min. 

Average. 

Max. 

Min. 

Average. 

Average  10  American  tests  
Average  8  German  tests   

4162 
4189 

2097 
850 

3393 
2118 

12.4 
18.3 

2.275 
9.0 

8.89 
12.78 

Comparison  with  clay  brick. — It  will  be  of  interest  to  compare  with 
these  the  results  of  a  series  of  tests  recently  published,*  which  were 
made  in  1903  by  Prof.  Woolson  in  an  extensive  series  of  clay  bricks. 
The  bricks  were  all  made  in  New  Jersey,  and  were  fair  average  samples, 
taken  from  stock  piles.  For  convenience  of  references  the  bricks 
have  been  divided  into  two  classes — front  brick  and  common  brick — 
and  the  two  classes  are  separately  averaged  in  the  following  table. 

TABLE.  58. 
SUMMARY  OF  CLAY-BRICK  TESTS.     (WOOLSON.) 


Compressive  Strength, 
Pounds  per  Square  Inch. 

Absorption,  Per  Cent. 

Max. 

Min. 

Average. 

Max. 

Min! 

Average. 

Front  brick 

13,873 
11,058 

5583 
661 

8805 
3785 

8.61 
15.38 

1.34 
6.89 

4.20 
12.04 

Common  brick 

Even  the  common  clay  brick,  therefore,  is  stronger  and  denser  than 
the  lime-sand  brick. 

*  Vol.  6,  Reports  N.  J.  Geological  Survey.     Clay  Industry,  p.  256.     1904. 


146 


CEMENTS,  LIMES,  AND  PLASTERS. 


Comparison  with  sandstone. — Lime-sand  bricks  are  frequently  com- 
pared, as  to  physical  properties,  with  natural  sandstones.  One  example 
of  such  a  comparison,  made  by  an  enthusiastic  advocate  of  lime-sand 
bricks,  is  given  on  page  142  of  this  volume.  In  the  table  below  the 
results  of  a  large  number  of  tests  of  natural  sandstones  are  summarized. 


.TABLE  5& 
SUMMARY  OF  TESTS  OF  NATURAL  SANDSTONE. 


Corripressive  Strength, 
Pounds   per   Square    Inch. 

Absorption,  Per  Cent. 

Max. 

Min. 

Average. 

Max. 

Min. 

Average. 

45  Wisconsin  sandstones  
9  Pennsylvania      '  ' 

13,669 
29,252 

16,894 
19,968 

1,658 
11,448 

4,945 
4,025 

6,429 
17,225 

12,192 
12,893 

15.22 

2.00 

7.46 

6  Massachusetts  and  Connect- 
icut sandstones  
17  New  York  sandstones  

Comparing  these  results  with  those  on  lime-sand  brick  given  in 
table  57  above,  it  will  be  seen  that  the  average  natural  sandstone  is  far 
superior  in  every  way  to  the  lime-sand  brick. 

Statistics. — In  its  recent  revival  the  lime-sand  brick  industry  in 
the  United  States  dates  back  only  to  1901,  at  which  date  a  plant 
was  established  at  Michigan  City,  Ind.  Since  that  time  numerous 
plants  have  been  established  throughout  the  country.  No  accurate 
statistics,  however,  are  available  as  regards  amount  and  value  of  total 
product.  In  this  connection  the  latest  issue  of  the  "Mineral  Resources 
of  the  United  States"  notes  that  "the  sand-lime  brick  industry,  men- 
tioned in  the  last  report,  made  considerable  progress  during  1903. 
Several  plants  had  their  product  on  the  market,  and  quite  a  number  of 
new  plants  were  built  during  the  year,  but  the  large  majority  were 
engaged  in  preliminary  work  and  put  no  product  on  the  market 
though  they  will  undoubtedly  be  factors  in  the  production  of  1904. 
Returns  covering  16  operating  plants  show  a  marketed  product  of 
20,860,000  brick,  valued  at  $155,400,  an  average  of  $7.45  per  thousand. 
Of  these  16  operating  plants  three  were  located  in  Michigan,  two  each 
in  California,  New  York,  South  Dakota,  and  Texas,  and  one  each  in 
Arizona,  Maryland,  New  Jersey,  North  Carolina,  and  Pennsylvania." 

List  of  references  on  lime-sand  bricks. — A  number  of  books  and 
papers  dealing  with  the  manufacture  and  properties  of  lime-sand  bricks 
are  listed  below.  By  far  the  most  important  of  these,  from  either  a 


MANUFACTURE  AND  PROPERTIES  OF  LIME-SAND   BRICKS.      147 

theoretical  or  industrial  point  of  view,  are  the  two  detailed  papers  by 
S.  V.  Peppel. 

Gowdy,  J.  K.     Sand  bricks  in  France.     U.  S.  Consular  Reports,  No.  1547. 

Jan.,  1903. 
Kitchell,  W.    'Lime  brick  manufacture.     2d  Ann.  Rep.  New  Jersey  Geological 

Survey,  pp.  107-108.     1856. 

Marston,  A.     Tests  of  sand-lime  and  sand-cement  brick  and  concrete  building- 
blocks.     Engineering  News,  vol.  51,  pp.  387-389.     April  21,  1904. 
Mason,  F.  H.     Calcareous  brick  and  stone  manufacture  in  Germany.     Daily 

U.  S.  Consular  Report,  No.  1765,  Oct.  3,  1903. 
Owen,  W.     Patent  lime  and  sand  block.     Journ.  Soc.  Chem.  Industry,  vol.  19, 

p  147.     1899. 

Peppel,  S.  V.     The  manufacture  and  properties  of  artificial  sandstone.     Trans- 
actions   American    Ceramic  Society,  vol.  4,  1903;    Engineering  News, 

vol.  49,  pp.  70-73,  Jan.  22    1903. 
PeppeL  S.  V.     Further  contributions  to  the  manufacture  of  artificial  sandstone 

or  sand  brick.     Transactions  American  Ceramic  Society,  vol.  5,  1903. 
Rochmanow.     Basic  fire-proof  bricks.     Thonindustrie  Zeitung,  vol.  27,  p.  108. 

Abstract  in  Journal  Soc.  Chem.  Industry,  vol.  22,  p.  421.     1903. 
Schwarz.     Sand  bricks.      Abstract  in  Journal  Soc.  Chem.  Industry,  vol.  21, 

p.  1183-1184.     1902. 
Wolff,  L.  C.     Bricks  of  lime  and  sand.     Thonindustrie  Zeitung,  vol.  23,  pp. 

854-859.     Abstract  in  Journal  Soc.  Chem.   Industry,  vol.   19,  p.  48. 

1899. 
Anon.     The  Schwarz  drying  and  mixing  machine  for  manufacturing  lime-sand 

brick.     Engineering  News,  vol.  49,  p.  179.     Feb.  19,  1903. 


PART  III.     MAGNESIA  AND  OXYCHLORIDE 

CEMENTS. 


CHAPTER  XI. 
SOURCES  AND  PREPARATION  OF  MAGNESIA. 

MAGNESIA,  or'  magnesium  oxide  (MgO),  though  possessing  very 
marked  cementing  properties,  is  at  present  too  expensive  to  be  used 
as  a  cementing  material  for  ordinary  structural  purposes.  It  merits 
discussion  in  this  volume,  however,  because  (a)  it  is  the  basis  of  an 
extensive  magnesia  brick  industry;  (6)  under  certain  conditions  it 
posessses  hydraulic  properties;  and  (c)  the  facts  brought  out  in  a  de- 
scription of  the  manufacture  of  magnesia  and  magnesia  brick  may  serve 
to  throw  some  light  on  the  vexed  question  of  the  part  played  by  mag- 
nesia when  present  in  hydraulic  cements. 

Sources  of  magnesia. — Magnesia  may  be  obtained  on  a  commercial 
scale  either  by  burning  the  mineral  magnesite;  a  natural  carbonate 
of  magnesium,  or  by  chemical  methods  practiced  on  other  natural  sources 
of  magnesium  salts  such  as  highly  magnesian  limestones  or  even  sea- 
water.  At  present  magnesite  is  by  far  the  most  important  source  of 
magnesia,  but  the  chemical  methods  of  extraction  may  be  of  service 
under  certain  commercial  conditions.  All  the  sources  and  methods 
will  therefore  be  considered  in  the  present  chapter,  magnesite  being 
first  discussed  and  then  the  chemical  sources  of  supply.  The  chapter 
following  will  be  devoted  to  consideration  of  the  properties  and  uses 
of  the  magnesia,  however  obtained,  and  the  manufacture  and  proper- 
ties  of  magnesia  bricks. 

Magnesite  as  a  Source  of  Magnesia. 

Composition  and  character  of  magnesite. — Magnesite  occurs  com- 
monly as  a  fine-grained,  compact  mineral,  varying  from  white  to  yellow- 

148 


SOURCES  AND  PREPARATION  OF  MAGNESIA.  149 

ish  in  color  according  to  its  degree  of  purity.  It  is  hard  and  brittle; 
if  cold  hydrochloric  acid  be  dropped  upon  it  no  action  takes  place, 
but  hot  acid  causes  brisk  effervescence. 

In  composition  it  is  a  magnesium  carbonate,  corresponding  to  the 
formula  MgCO.s.  This  is  equivalent  to  magnesium  carbonate  (MgCOs) 
=  magnesium  oxide  or  magnesia  (MgO)+  carbon  dioxide  (CO2).  Quan- 
titatively, pure  magnesite  (MgC03)  consists  of  47.6  per  cent  magnesia 
(MgO),  52.4  per  cent  carbon  dioxide  (CC>2). 

Occurrence  and  origin  of  magnesite. — Magnesite,  when  in  bodies 
of  workable  size,  occurs  commonly  in  one  of  three  associations,  the 
methods  of  origin  of  the  deposits  being  different  in  each  case.  The 
three  types  of  deposits  are: 

(1)  Magnesite  occurs  most  commonly  in  the  form  of  irregular  veins 
or  pockets  in  serpentine  or  other  magnesian  igneous  rocks.     In  this 
case  the  magnesite  has  been  formed  as  a  decomposition  product  aris- 
ing from  the  decay  of  the  igneous  rock. 

(2)  Magnesite  occurs  in  the  form  of  beds  associated  with  deposits 
of  rock  salt,  gypsum,  etc.     In  this  case  the  magnesite  deposit  has  un- 
doubtedly  originated   by   direct   deposition   of   magnesium   carbonate 
from  bodies  of  concentrated  saline  waters. 

(3)  Magnesite  also  occurs  in  the  form  of  beds  interstratified  with 
shales,  limestones,  etc.     Magnesite  deposits  of  this  type  are  commonly 
ascribed  to  the  replacement  of  the  lime  (in  a  limestone)  by  magnesia 
carried  in  by  percolating  waters.     This  may  be  true  in  some  cases,  but 
such  deposits  may  also  have  originated  by  direct  deposition,  as  described 
under  (2),  above. 

In  most  of  the  workable  magnesite  deposits  noted  below,  however, 
the  first  method  of  origin  is  the  true  explanation. 

Distribution  of  magnesite  deposits. — The  magnesite  deposits  now 
exploited  on  a  sufficient  scale  to  be  of  commercial  interest  occur  in 
Austria,  Germany,  Greece,  Hungary,  India,  and  the  United  States. 
Workable  deposits  also  occur  in  Canada,  but  as  yet  have  not  been  suffi- 
ciently opened  up  to  determine  their  commerical  importance. 

Foreign  localities.  — The  principal  Austrian  magnesite  deposits  are 
near  Mittendorf,  in  Styria,  and  near  Tolsvar,  in  the  province  of  Minsan, 
Hungary.  The  Styrian  magnesite  averages  about  88  per  cent  mag- 
nesium carbonate  with  about  8  per  cent  of  silica,  alumina,  and  iron 
oxide.  The  Hungarian  product  is  a  purer  magnesite,  carrying  92  to 
95  per  cent  magnesium  carbonate,  with  3  or  4  per  cent  iron  oxide. 

In  Germany  the  deposits  now  worked  occur  near  Kosewitz  and 
Frankenstein,  in  Silesia,  and  are  principally  worked  in  connection  with 


150  CEMENTS,  LIMES,  AND  PLASTERS. 

the  manufacture  of  carbonic  acid.  The  product  will  carry  about  92 
to  94  per  cent  magnesium  carbonate,  the  principal  impurity  being 
4  to  5  per  cent  of  silica. 

The  principal  Grecian  deposits  are  on  the  island  of  Euboea,  on  the 
east  coast  of  Greece,  and  also  near  Corinth.  The  product  is  a  very 
pure  magnesite,  averaging  95  per  cent  magnesium  carbonate.  It  is 
low  in  clayey  matter,  the  principal  impurity  being  3  to  5  per  cent  of 

lime  carbonate.  The  Grecian  deposits  are  worked  in  primitive  fashion 
by  pick  and  shovel.  The  mines,  or  quarries,  are  usually  worked  as 
open  cuts.  As  the  rock  is  broken  in  the  mines  it  is  brought  to  the  sur- 
face, where  the  magnesite  is  sorted  out.  It  is  then  loaded  into  small 
carts  and  drawn  to  a  narrow-gauge  gravity  railway,  when  the  mag- 
nesite is  loaded  into  one-ton  cars  and  sent  forward  to  the  shipping  port, 
usually  Kymassi  or  St.  Theodore.  The  cost  of  producing  the  mineral 
is  about  $3.50  per  ton,  transportation  charges  to  the  seaport  about 
$1.00,  and  freight  to  the  United  States  about  $2.50  per  ton. 

Magnesite  is  found  in  considerable  quantity  in  southern  India, 
about  two  hundred  miles  from  Madras.  Deposits  recently  exploited 
extend  over  1500  acres.  The  railroad  from  Madras  to  Calicut  runs 
through  these  deposits,  near  the  center  of  the  magnesite  area.  The 
material  can  be  shipped,  in  any  desired  quantity,  either  from  Madras 
on  the  east  coast  or  from  Beypore  on  the  west  coast.  As  described 
to  the  present  writer  by  the  owner,  the  magnesite  occurs  in  beds  or 
veins  of  varying  thickness,  from  a  few  inches  up  to  several  feet,  the 
magnesite  beds  being  separated  by  bodies  of  disintegrated  material. 
An  analysis  o.f  this  magnesite  is  given  in  column  1,  Table  63.  This 
was  made  on  a  100-ton  sample  of  crude  rock.  Another  analysis  of 
Indian  magnesite,  quoted  in  column  2  of  the  same  table,  accompanied 
a  series  of  specimens  exhibited  at  the  St.  Louis  Exposition  in  1904. 

American  localities. — The  principal  American  magnesite  deposits 
are  in  California  and  in  Quebec,  Canada. 

The  California  deposits  are  described*  as  follows:  "The  principal 
producing  point  in  California  is  in  the  vicinity  of  Porterville,  Tulare 
County,  though  a  small  quantity  still  comes  from  Chiles  Valley  and 
Pope  Valley,  Napa  County.  At  Porterville  there  are  several  deposits. 
The  main  deposit  at  the  opening  carries  a  small  vein,  but  at  the  end 
of  the  240-foot  tunnel  the  deposit  is  40  feet  wide,  and  there  are  said 
to  be  several  million  tons  now  in  sight.  At  this  place  calcining  furnaces 
have  been  erected  and  are  in  operation.  The  mineral  crops  out  boldly  in 

*  Mineral  Resources  of  the  U.  S.  for  1903,  pp.  1131-1135.     1904. 


SOURCES  AND   PREPARATION  OF  MAGNESIA.  151 

distinct  veins,  having  a  general  strike  northeast  and  southwest,  and 
there  are  spurs  running  in  several  instances  at  nearly  right  angles  with 
the  primary  veins.  On  the  surface  the  veins  are  fom  2  inches  to  10 
feet  wide.  They  cover  an  area  of  over  500  acres.  In  Pope  and  Chiles 
valleys,  Napa  County,  there  are  somewhat  extensive  deposits  which 
were  formerly  worked,  but  hauling  by  team  to  railroad  made  them 
more  expensive  to  operate  than  the  mines  at  Porterville.  In  Placer 
County  there  is  a  more  extensive  deposit  than  elsewhere  in  California, 
but  it  is  in  an  almost  inaccessible  mountain  region  where  a  very  costly 
road  would  be  necessary  to  get  the  product  out,  and  the  deposit  has 
therefore  not  been  utilized.  Near  Sanger,  Fresno  County,  7  miles  from 
Centerville,  another  deposit  is  now  being  opened.  A  deposit  has  been 
discovered  also  near  Walkers  Pass,  Kern  County,  but  it  has  never  been 
opened.  There  are  also  unutilized  deposits  near  Morgan  Hill,  Santa 
Clara  County. 

"The  extensive  deposits  of  magnesite  on  Red  Mountain,  at  a  point 
where  Stanislaus,  Alameda,  and  Santa  Clara  counties  join,  are  now 
being  opened  by  the  American  Magnesite  Company,  of  Chicago,  which 
has  obtained  control  of  the  numerous  claims  heretofore  owned  by 
individuals.  None  of  them  have  been  at  all  thoroughly  prospected 
as  yet,  though  there  are  numerous  boulders  or  large  croppings,  some 
from  30  to  150  feet  wide,  supposed  to  cover  extensive  beds  beneath. 
The  parent  company  is  the  American  Magnesite  Company,  organized 
under  the  laws  of  the  State  of  Maine,  with  Mr.  G.  Watson  French,  of 
Chicago,  as  president  and  Mr.  H.  C.  Stillwell,  of  Fruitvale,  Alameda 
County,  CaL,  as  vice-president  and  Pacific  coast  agent;  Mr.  Charles 
H.  Spinks,  of  Berkeley,  CaL,  is  to  manage  the  mines.  One  of  the  sub- 
sidiary companies  is  the  Rose  Brick  Company,  which  is  to  manufac- 
ture magnesite  brick,  at  Oakland,  Cal.;  the  American  Carbonic  Acid 
Gas  Company  is  another,  of  which  Mr.  John  Deere  is  president  and 
Mr.  George  A.  Wayman,  manager.  The  third  corporation  is  the  Plastic 
Construction  Company,  of  which  Mr.  Edwin  D.  Weary,  of  Chicago, 
is  president.  This  company  controls  the  American  rights  for  making 
a  fire-proof  construction  material  as  well  as  a  patent  brick.  This  factory 
will  also  be  in  Oakland. 

"The  mines  of  this  company  are  nearly  all  in  Santa  Clara  County, 
with  a  few  in  Stanislaus,  near  the  Alameda  County  line.  The  Ala- 
meda County  supervisors  are  building  a  wagon-road  from  the  mines  to 
Livermore,  where  the  railroad  is  met.  There  are  twenty-seven  mining 
claims  in  the  group,  and  several  are  at  present  being  opened.  Only 
a  few  car-loads  for  sample  purposes  have  been  shipped  since  the  com 


152 


CEMENTS,  LIMES,  AND  PLASTERS. 


pletion  of  the  new  organization,  but  it  is  expected  that  the  properties 
will  shortly  be  opened  on  an  extensive  scale." 

Recently  several  large  deposits  of  magnesite  have  been  discovered  * 
in  the  township  of  Grenville,  Argenteuil  County,  in  the  province  of 
Quebec.  Large  boulders  of  the  mineral  were  found,  and  finally  the 
magnesite  was  found  in  place.  One  of  these  deposits,  which  showed 
an  outcrop  90  feet  long  and  20  feet  broad,  is  in  the  north  half  of  the 
eighteenth  lot  of  the  eleventh  range'  of  Grenville  township.  Another 
outcrop,  100  feet  wide  and  traceable  for  a  quarter  mile  in  length,  is 
on  the  north  half  of  the  sixteenth  lot  of  the  ninth  range. 

The  following  analyses  of  magnesite  from  these  deposits  were  made 
by  G.  C.  Hoffmann,  and  are  quoted  from  the  report  cited  below.* 

TABLE  60. 
ANALYSES  OF  MAGNESITE  FROM  QUEBEC,  CANADA. 


1. 

2.     ' 

3. 

4. 

5. 

6. 

7. 

Magnesium  carbonate  (MgCO3) 
•Calcium  carbonate  (CaCO3).  .  . 
Magnesia  (MgO)  as  silicate.  .  .  . 

77.62 
16.07 
3.50 

74.68 
18.89 
3.71 

78.08 
15.57 
4.18 

77.16 
10.78 
6.14 

76.09 
16.00 
4.29 

76.97 
13.14 

5.87 

49.71 
30.14 
9.17 

8. 

9. 

10. 

11. 

12. 

13. 

Magnesium  carbonate  (MgCO3) 

75  69 

82  72 

77  07 

85  00 

95  50 

81  27 

'Calcium  carbonate  (CaCO3) 

19  71 

12  36 

16  28 

10  80 

tr 

13  64 

Magnesia  (MgO)  as  silicate 

3  08 

2  53 

3  22 

n   d 

n  d 

3  66 

It  will  be  seen  that  this  Canadian  magnesite,  differs  from  all  the 
-other  magnesites  known  to  commerce,  in  that  it  contains  a  comparatively 
large  percentage  of  lime  carbonate  as  its  principal  impurity. 

Production  and  imports  of  magnesite.— In  the  following  tables  (61 
and  62)  statistics  regarding  the  domestic  production  and  the  imports 
-of  magnesia  and  magnesite  are  given.  It  will  be  seen  that  in  1903  the 
value  of  the  United  States  production  amounted  to  less  than  3  per  cent 
of  the  total  value  of  magnesia  and  magnesite  used  in  this  country. 

Analyses  of  commercial  magnesite. — As  magnesite  is  simply  mag- 
nesium carbonate,  a  theoretically  pure  magnesite  would  consist  of  47.6 
per  cent  magnesia  (MgO)  and  52.4  per  cent  carbon  dioxide  (C02).  De- 
posits of  magnesite,  however,  rarely  yield  any  considerable  amount  of 
material  of  this  degree  of  purity,  and  commercial  magnesite  may  con- 
tain as  high  as  10  per  cent  or  thereabouts  of  lime  carbonate,  silica, 
.alumina,  iron  oxide,  etc. 

*  Ann.  Rep.  Canadian  Geol.  Survey,  vol.  13,  Report  R,  pp.  14-19.     1903. 


SOURCES  AND   PREPARATION  OF  MAGNESIA. 


153 


TABLE  61. 

QUANTITY  AND  VALUE  OF  CRUDE  MAGNESITE  PRODUCED  IN  THE  UNITED  STATES, 

1891-1903. 


Year. 

Quantity. 

Value. 

Year. 

Quantity. 

Value. 

1891         

Short  tons. 
439 

$4,390 

1898  

Short  tons. 

1  263 

$19  075 

1892     

1,004 

10,040 

1899  

1,280 

18  480 

1893   

704 

7,040 

1900  

2,252 

19  333 

1894 

1  440 

10240 

1901 

3  500 

10  500 

1895 

2  220 

17,000 

1902 

2  830 

8  490 

1896 

1  500 

11,000 

1903..    . 

3  744 

10  595 

1897 

1,143 

13,671 

TABLE  62. 
IMPORTS  OF  MAGNESITE  INTO  THE  UNITED  STATES  IN  1903. 


Quantity. 

Value. 

Magnesia  : 
Calcined,  medicinal    

Pounds. 
34,586 

$4  412 

Carbonate  of,  medicinal  

10,569 

765 

Sulphate  of  or  Epsom,  salts 

2  392  831 

11  326 

Magnesite  : 
Calcined   not  purified 

73  534  690 

311  396 

Crude 

36  017  637 

150  002 

TABLE  63. 
ANALYSES  OF  MAGNESITE. 


1. 

2. 

3. 

4. 

5. 

Silica  (SiO2)      

2.20 
}    0.30 

0.59 
46.59 
49.63 
0.83 

0.22 
0.30 

n.  d. 
47.35 
51.44 
0.27 

0.30 
1.62 

n.  d. 
46.00 
51.23 
n.d. 

0.52 
trace 

2.25 
45.28 
51.61 
0.34 

0.52 
0.08 

2.46 
44.96 
51.44 
0.54 

Alumina  (A12O3)   

Iron  oxide  (Fe2O3) 

Lime  (CaO) 

Magnesia  (MgO) 

Carbon  dioxide  (CO2)  ,. 
Water 

6. 

7. 

8. 

9. 

Silica  (SiO2)          

1.0 
}    3.0-6.0 

0.28-1.12 
42.84-45.70 
n.  d. 

4.00 
4.00 

n.  d. 
41.89 
n.  d. 

0.8 

ri.ii 

13.  2/ 
0.06 
45.12 
49.72 

4.5-5.25 
1.5 

0.6-0.7 
46.0-48.0 
46.0-50.0 

Alumina  (Al^Oa)  

Iron  oxide  (F^Os^    

I  ime  (CaO) 

Magnesia  (MgO)  

Carbon  dioxide  (CO2)  

1.  200  miles  from  Madras,  British  India.     Private  communication. 

2.  India.     Indian  Exhibit,  World's  Fair,  St.  Louis,  1904. 

3.  Dept.  of  Ufa,  Southern  Urals,  Russia.     "Mineral  Industry,"  vol.  10,  p.  439. 

4.  Mondondi,  Greece.     U.  S.  Consular  Reports,  No.  168,  1900. 

5.  Eubrea,  Greece.     Proc.  Inst.  C.  E.,  vol.  112,  p.  381. 

6.  Styria,  Austria.     Proc.  Inst.  C.  E.,  vol.  112,  p.  381. 

7.  Styria,  Austria.      Eng.  and  Mining  Journal,  March   10,   1900. 

8.  Minsan,   Hungary.      Eng.   and   Mining  Journal,   March   10,   1900. 

9.  Frankenstein,  Silesia  (Germany).     Eng.  and  Mining  Journal,  March  10,  1900. 


154  CEMENTS,  LIMES,  AND  PLASTERS. 

Effects  of  heatingmagnesite.— If  magnesite  (MgC03)  be  strongly 
heated,  the  effect  (as  with  lime  carbonate)  is  to  drive  off  the  carbon 
dioxide  (CC^),  leaving  magnesia  (MgO)  as  a  white  solid.  A  curious 
and  technologically  important  phenomenon  connected  with  the  tem- 
perature employed  is  to  be  noted.  If  the  calcination  be  carried  on 
quickly  at  a  red  heat,  the  magnesia  resulting  will  have  a  specific  gravity 
of  3.00  to  3.07;  while  if  the  calcination  is  long  continued  or  carried 
on  at  a  higher  temperature  the  resulting  magnesia  will  be  much  denser, 
possessing  a  specific  gravity  of  3.61  to  3.80. 

The  technologic  importance  of  the  two  forms  of  magnesia  lies  in 
the  fact  that  the  lightly  burned  magnesia  will  slake  with  water  and 
if  then  exposed  to  air  will  finally  recarbonate  and  harden  slowly,  just 
as  lime  does.  The  denser,  higher-burned  magnesia,  however,  will  not 
take  up  either  water  or  carbon  dioxide  from  the  atmosphere.  Another 
difference  of  commercial  interest  lies  in  the  fact  that  the  light  form 
of  magnesite  possesses  a  certain  amount  of  plasticity,  so  that  it  can 
be  molded  into  shape  under  heavy  pressure,  while  the  dense  form  of 
magnesia  is  entirely  devoid  of  plasticity. 

Methods  of  burning  magnesite. — For  calcining  magnesite  at  low 
temperature,  so  as  to  obtain  lightly  burned  magnesia,  kilns  closely  similar 
to  ordinary  lime-kilns  are  employed  in  California.  The  kilns  in  use  at 
one  California  magnesia-plant  are  built  in  the  -form  of  a  frustum  of  a 
cone,  the  broader  part  downwards.  These  kilns  are  about  19  feet  in 
height,  3  feet  in  diameter  at  the  top,  and  7  feet  in  diameter  at  the  base. 
Drawing-doors  are  placed  at  the  base,  while  draft  is  obtained  by  suction, 
air  being  drawn  through  a  flue  near  the  top  of  the  kiln.  These  kilns  are 
charged  with  coke  and  magnesite  mixed,  in  about  the  proportion  of 
300  Ibs.  magnesite  to  20  Ibs.  of  coke.  The  product  is  the  light  form 
of  magnesite,  and  is  probably  not  entirely  decarbonated.  This  fuel 
consumption  would  amount  to  about  14  per  cent  on  the  weight  of  mag- 
nesia produced. 

When  the  dead-burnt  or  heavy  magnesia  is  required,  the  burning 
must  take  place  at  much  higher  temperatures.  This  kind  of  magnesia 
may  be  prepared  in  reverberatory  furnaces,  in  cupolas  lined  with  silicious 
material,  or  in  highly  heated  gas-kilns.* 

The  practice  in  Greece  is  described  f  as  follows : 

"  At  the  Greek  magnesite  mines,  until  recently  roughly  built  kilns 
fired  by  wood  were  employed  for  catcining  the  ore,  which  required  a 

*  Proc.  Inst.  Civil  Engineers,  vol.  112,  p.  381.     1893. 
f  Engineering  and  Mining  Journal,  Feb.  28,  1903 


SOURCES  AND  PREPARATION   OF  MAGNESIA. 


155 


large  quantity  of  fuel.  In  recent  years,  however,  modern  shaft  cal- 
ciners  have  been  built  and  a  soft  lignite  coal  is  used.  When  calcined 
magnesite  falls  into  powder  and  is  apt  to  choke  the  lower  or  cooler 
portion  of  the  kiln,  preventing  the  access  of  air  and  heated  gases  to 
the  upper  portion.  The  shaft  furnaces  are  constructed  to  overcome 
this  result.  The  quantity  of  fuel  required  is  from  15  to  20  per  cent 
of  the  weight  of  magnesite,  equivalent  to  a  fuel  consumption  of  30  to  40 
per  cent  on  the  weight  of  magnesia  produced.  In  some  cases  the  cal- 
cining is  done  in  a  double-hearth  reverberatory  furnace,  where  the  flame 
is  brought  into  direct  contact  with  the  freshly  charged  magnesite  on 
the  upper  hearth,  the  operation  being  completed  on  the  lower  hearth, 
which  is  the  hotter  of  the  two." 

Composition  of  the  product. — The  analyses  given  in  Table  64  will 
serve  to  show  the  composition  of  the  burned  product,  which  naturally 
varies  according  to  that  of  the  magnesite  from  which  it  is  made. 

TABLE  64. 
ANALYSES  OF  CALCINED  MAGNESITE  (  =  MAGNESIA). 


1. 

2. 

3. 

4. 

5. 

6. 

7. 

.Silica  (SiO2)       

0.98 

0.16 

0.17 

0.50 

1.2 

0.73-  7  98 

Alumina  (A12O3)  

0.10 

0.10 

2.38 

Iron  oxide  (Fe2O3)  

5.70 

7.40 

5.02 

6.50 

6.90 

\  13.0 

0.56-  3.54 

Lime  (CaO)  

1.88 

2.66 

1.50 

1.70 

7.3 

0.83-10.92 

Magnesia  (MgO)   

91.10 

89.36 

90.42 

90.95 

9i.50 

77.6 

82.46-95.36 

€arbon  dioxide  (CO2).  .  . 

n.  d. 

n.  d. 

0.46 

n.  d. 

n.  d. 

1,  2.  Burned  Hungarian  magnesite.    Iron  Age,  Jan.  15,  1903,  pp.  20,  21. 
3,  4,  5.      '  Mineral  Industry,  vol.  10,  p.  439. 

6.  Styrian  (Austrian)  magnesite.     Proc.  Inst.  C.  E.,  vol.  112,  p.  381. 

7.  "       Grecian  magnesite.     Proc.  Inst.  C.  E.,  vol.  112,  p.  381. 

Use  of 'magnesite  for  preparation  of  carbonic  acid,  etc. — California 
practice  in  the  manufacture  of  carbonic  acid  from  magnesite  is  de- 
scribed as  follows. in  a  recent  report :* 

"  In  the  manufacture  of  carbonic-acid  gas,  the  gas  is  extracted  from 
the  jmagnesite  by  calcining  and  the  remaining  calcined  material  is  sold 
to  the  manufacturers  of  wood-pulp  paper.  The  best  English  coke  is 
used  for  calcining  the  magnesite.  From  one  short  ton  of  magnesite, 
after  removing  the  gas;  they  obtain  about  1200  Ibs.  of  residue,  which 
is  partly  calcined  magnesite  still  carrying  some  20  per  cent  of  gas.  In 
the  process  about  500  Ibs.  of  gas  is  obtained  when  finally  compressed 


*  Mineral  Resources  of  the  U.  S.  for  1903,  p.  1133.     1904. 


156  CEMENTS,  LIMES,  AND  PLASTERS. 

into  liquid  form.  For  every  ton  of  magnesite  about  500  Ibs.  of  coke 
is  burned,  and  this,  containing  about  97  per  cent  of  carbon,  also  fur- 
nishes considerable  gas.  The  steel  cylinders  for  holding  the  liquid 
gas  are  &  inch  thick  and  5  by  49  inches  long,  and  hold  about  25  Ibs. 
The  pressure  on  the  cylinder  at  60°  F.  is  about  850  Ibs.,  a  three-stage 
compressor  being  used.  In  shipping  the  liquid  gas  through  the  central 
valleys  and  to  Arizona  the  heat  in  the^cars  sometimes  runs  as  high  as 
145°,  the  pressure  being  increased  thereby.  The  cylinders  containing 
the  liquefied  gas  are  shipped  to  soda-water  manufacturers,  ice-fac- 
tories, refrigerating-plants,  breweries,  bar-rooms,  etq.  The  cylinders 
with  the  liquid  gas  are  shipped  all  over  the  Pacific  coast,  from  San  Fran- 
cisco, even  the  British  war  vessels  stationed  at  British  Columbia  using 
the  gas  for  their  refrigerating-plants,  The  San  Francisco  carbonic- 
acid-gas  makers  use  about  1000  tons  of  crude  magnesite  annually. 

As  stated,  the  wood-pulp  paper-mills  of  California  and  Oregon  use 
the  calcined  magnesite.  They  transform  it  into  a  sulphite  of  magnesia 
and  use  it  as  a  digester  for  the  wood  pulp.  To  make  this  sulphite  they 
put  the  material  into  a  tank  and  pass  sulphurous  fumes  through  it. 
After  being  used  as  a  digester  they  add  a  little  lime  and  make  the  '  pearl 
hardening '  of  commerce  to  be  used  as  a  l  filler '  for  the  paper. " 

Magnesian  Limestones  as  Sources  of  Magnesia. 

Highly  magnesian  limestones,  approaching  dolomite  in  composition, 
may  be  regarded  as  possible  sources  of  magnesia.  The  general  char- 
acters of  such  limestones  are  discussed  in  some  detail  in  earlier  chapters 
of  this  volume,  and  reference  should  be  made  to  pp.  90-91  for  data 
on  these  points. 

Occurrence  of  magnesian  limestones  in  the  U.  S. — Magnesian  lime- 
stones are  so  widely  distributed  throughout  the  United  States  that 
no  satisfactory  summary  of  their  distribution  can  be  given  here.  On 
pp.  92-94  is  given  a  list  of  reports  on  the  limestones  of  the  various 
states  and  territories.  Reference  to  these  reports  will  furnish  data 
on  the  local  distribution  and  composition  of  magnesian  limestones,  as 
well  as  of  other  types. 

Analyses  of  magnesian  limestones. — In  the  following  table  analyses 
of  a  number  of  highly  magnesian  limestones  from  various  localities 
in  the  United  States  are  presented.  It  will  be  seen  that -these  range 
from  15  to  over  22  per  cent  in  magnesia  (MgO),  which  is  about 
equivalent  to  a  range  of  from  32  to  45  per  cent  magnesium  carbonate 
(MgC03). 


SOURCES  AND  PREPARATION  OF  MAGNESIA. 


157 


TABLE  65. 
ANALYSES  OF  HIGHLY  MAGNESIAN  LIMESTONES,  U.  S. 


1. 

2. 

3. 

4. 

5. 

Silica  (SiO  )           

3.24 

7.75 

0  48 

0  08 

Alumina  (A-l^Oo)          

0.17 

/ 

1      n    on 

Iron  oxide  (Fe2O3)   

0.23 

1    1.48 

10  02 

j    0.20 

0.25 

Lime  (CaO)     

29.58 

31.00 

31  01 

31  31 

30  46 

20  84 

16  46 

21  79 

21  03 

21  4g 

Carbon  dioxide  (CO2)  

45.54 

42.47 

47.35 

46.98 

47.58 

6. 

7. 

8. 

9. 

10. 

Silica  (SiO2)                 .  .    ... 

0  73 

0  44 

0  87 

0  20 

0  70 

Alumina  (A12O3)          

f  1  22 

0  57 

1         ^      00 

/O  95 

Iron  doxie  (Fe2O3)      

I    0.35 

[  trace 

0  25 

|    0.23 

\  0  80 

Lime  (CaO)           

32  73 

30.73 

31  40 

30  04 

30  50 

Magnesia  (MgO)     .  .  .  .  

19  37 

20  87 

19  95 

22  28 

20  05 

Carbon  dioxide  (CO2)      .  .... 

46  58 

45  85 

n  d 

47  14 

45  24 

1.  Morrisville,  Calhoun  County,  Ala.      W,   F.   Hillebrand.  analyst.      Bulletin  60,  U.  S.   Geol. 

Survey,  p.  159. 

2.  S.  16,  T.  7,  R.  7,  E.  Talladega  County,  Ala.     J.  B.  Britton,  analyst.     Rep.  Ala.  Geol.  Survey 

for  1875,  pp.  149,  150. 

3.  Inyo  Marble  Co.,  Inyo,  Calif.     20th  Ann.  Rep.  U.  S    Geol.  Survey,  pt.  6,  p.  359. 

4.  East  Canaan,  Conn.     20th  Ann.  Rep.  U.  S.  Geol.  Survey,  pt.  6,  p.  370. 

5.  Canaan,  Conn.     J.  S.  Adams,  analyst.     20th  Ann.  Rep.  U.  S.  Geol.  Survey,  pt.  6,  p.  370. 

6.  Jasper,  Ga.     W.  H.  Emerson,  analyst.     Bulletin  No.   1,  Ga.  Geol.  Survey,  p.  87. 

7.  Cockeysville,  Md.     J.   E.  Whitfield,  analyst.     Bulletin  60,  U.  S.  Geol.  Survey,  p.   159. 

8.  Ossining,  N.  Y.     H.  Ries,  analyst.     Bulletin  44,  N.  Y.  State  Museum,  p.  829. 

9.  Tuckahoe,  N.  Y.     Ledoux,  analyst.     20th  Ann.  Rep.  U.  S.  Geol.  Survey,  pt.  6,  p.  427. 
10.   Gates,  Monroe  County,  N.  Y.     D.  H.  Newland,  analyst.     Bulletin  44,  N.  Y.  State  Museum.. 

p.  796. 

Extraction  of  magnesia  from  magnesian  limestone. — Two  principal 
processes  have  been  suggested  for  extracting  magnesia  from  magnesian 
limestone. 

Scheibler  process. — The  mixture  of  lime  and  magnesia  left  by  burn- 
ing magnesian  limestone  is  made  into  a  thick  milk  by  adding  suffi- 
cient water.  Into  this  solution  is  poured  water  containing  10  to  15 
per  cent,  by  volume,  of  molasses,  and  the  mixture  is  mechanically 
stirred.  In  a  few  moments  saccharate  of  lime  is  formed,  which  re- 
mains in  solution  while  the  magnesia  is  precipitated.  On  putting 
through  a  filter-press  the  magnesia  remains  behind,  while  the  saccha- 
rate of  lime  passes  through.  The  composition  of  the  magnesia  sa 
obtained  at  a  German  plant  was: 

Silica  (SiO2) ] 

Alumina  (A12O3) Y      1 .47  per  cent 

Iron  oxide  (Fe2O3) J 

Lime  (CaO) ! 2.18    "      " 

Magnesia  (MgO) , 95.99    "      " 

The  saccharate  of  lime  which  passed  through  the  filters  is  now  treated 
for  recovery  of  its  constituents.  Carbon  dioxide  precipitates  the  lime 
as  carbonate,  after  which  it  is  filtered  and  the  lime  carbonate  precipi- 


158  CEMENTS,  LIMES,  AND  PLASTERS. 

tate  washed.  The  filtrate  contains  the  molasses,  which  can  be  used 
over  again.  In  the  course  of  the  process  a  loss  of  5  to  10  per  cent  of 
molasses  occurs. 

,  Closson  process. — This  process  is  based  on  the  use  of  magnesium 
chloride,  and  is  therefore  of  value  at  points  such  as  Stassiurt,  where 
that  material  is  obtainable  as  a  cheap  by-product. 

Twenty  thousand  pounds  of  magnesium  chloride  is  mixed  with  the 
lime-magnesia  resulting  from  the  calcination  of  3000  Ibs.  of  magnesian 
limestone.  Water  is  added  to  give  a  thick  solution,  and  mechanical 
agitation  is  employed.  The  result  is  the  formation  of  lime  chloride, 
and  magnesia  hydrate.  On  passing  through  a  filter-press  the  magnesia 
hydrate  is  caught  on  the  filter,  while  the  lime  chloride  passes  through 
in  solution.  The  hydrate  is  washed  and  then  burned,  giving  one  ton 
of  magnesia,  The  magnesia  obtained  at  Horde  by  this  process  gave 
the  following  composition: 

Silica  (SiO2) ] 

Alumina  (A12O3) .  .  .- (•      1 .05  per  cent 

Iron  oxide  (Fe2O3) J 

Lime  (CaO) 1.94    "      " 

Magnesia  (MgO) 96.90    "      " 

The  lime-chloride  solution  is  then  treated  for  recovery.  The  mate- 
rial is  carried  to  receptacles  like  those  in  which  blast-furnace  gases 
are  washed,  except  that  revolving  wheels  stir  the  chloride,  making  a 
thorough  mixture  of  the  gases  and  the  liquid.  Two  of  these  recepta- 
cles are  placed  together  back  to  back.  A  valve  which  can  be  reversed 
sends  the  gases  to  either  side  and  thus  keeps  up  a  continuous  working. 
Into  these  receptacles,  together  with  the  lime  chloride,  is  put  a  quantity 
of  the  lime-magnesia  resulting  from  the  calcination  of  magnesian  lime- 
stone. The  blast-furnace  gases  passing  through  precipitate  the  lime 
as  carbonate,  losing  their  carbon  dioxide  in  the  process,  and  are  thus 
rendered  more  combustible.  They  deposit,  besides,  a  considerable 
quantity  of  the  solid  materials  mechanically  carried  by  them  and  are 
thus  cleaned.  '  Magnesium  chloride  is  reformed,  remains  in  solution, 
and  is  drawn  off  and  filtered.  The  entire  process  shows  a  loss  of  5  to 
6  per  cent  of  magnesium  chloride. 

Sea-water  and  Brines  as  Sources  of  Magnesia. 

Sea-water  contains  small  percentages  of  different  magnesian  salts. 
In  the  manufacture  of  table  salt  from  sea-water  or  salt  brines,  these 
magnesian  compounds  are  incidentally  concentrated  so  as  to  be  put  in 
more  available  form. 


SOURCES  AND  PREPARATION  OF  MAGNESIA.  159 

Extraction  of  magnesia  from  sea- water.* — "Magnesia  is  made 
out  of  sea- water,  which  contains  about  4  Ibs.  magnesium  chloride  per 
cubic  yard  of  water,  on  a  large  scale  at  Aignes  Morts,  on  the  Mediter- 
ranean coast  of  France. 

"The  sea- water  is  pumped  into  a  tank  made  of  masonry,  and  at 
the  same  time  milk  of  lime  is  pumped  in,  in  the  proportion  of  1.5  per 
cent  of  lime  for  every  1  per  cent  of  magnesia.  From  this  first  tank 
the  liquid  flows  into  two  other  masonry  tanks,  when  thorough  mixing 
is  effected  mechanically.  It  is  then  filtered  into  shallow  excavations 
about  1000  feet  long  and  16  feet  wide,  in  the  bottom  of  which  is  a  bed 
of  clean  beach-sand.  When  enough  magnesia  has  been  collected  the 
liquid  supply  is  cut  off  and  the  precipitate  is  allowed  to  dry.  If  in 
summer,  it  is  dried  in  the  sun,  taking  twenty  to  thirty  days,  but  in  winter 
artificial  drying  is  necessary."  The  dried  magnesia  is  then  calcined  and 
treated  as  explained  in  discussing  the  burning  of  magnesite  (p.  154), 
and  the  manufacture  of  magnesia  bricks  (pp.  160-161). 

References  on  magnesite,  sources  of  magnesia,  etc. 

Hoffmann,  G.  C.  Magnesite  deposits  in  Quebec,  Canada.  Ann.  Rep.  Canadian 
Geological  Survey,  vol.  13,  Report  R,  pp.  14-19.  1903. 

Vlasto,  S.  J.  The  magnesite  industry  [in  Europe].  Engineering  and  Mining 
Journal,  March  10,  1900. 

.Watts,  W.  L.  [Magnesite  in  Santa  Clara  County,  California.]  llth  Ann. 
Rep.  California  State  Mineralogist,  pp.  374-375.  1893. 

Weiss,  N.     Magnesite  in  Hungary.     Iron  Age,  pp.  20-21.     Jan.  15,  1903. 

Yale,  C.  G.  [Magnesite  deposits  in  California.]  Mineral  Resources  U.  S. 
for  1903,  pp.  1131-1135.  1904. 

Anon.  Magnesite  [in  California].  12th  Ann.'  Rep.  California  State  Mineralo- 
gist, p.  328.  1894. 

Anon.    Magnesite  in  Greece.     U.  S.  Consular  Report,  No.  168,  1900. 

*  Lock,  C.  G.  W.     Economic  Mining,  p.  331. 


CHAPTER  XH. 

MAGNESIA  BRICKS  AND  OXYCHLORIDE  CEMENTS. 

t 

AFTER  magnesia  (MgO)  has  been  obtained  by  any  of  the  methods 
described  in  the  preceding  chapter,  it  is  put  to  use  in  two  quite  different 
ways.  As  the  products  differ  greatly  in  both  composition  and  use 
they  will  here  be  discussed  separately  under  the  headings  of  "Magnesia 
Bricks  "  and  "  Oxychloride  Cements  ". 

Magnesia  Bricks. 

Magnesia  bricks,  which  are  commonly  but  very  erroneously  called 
magnesite  bricks  in  the  trade,  are  largely  used  as  furnace  linings,  etc., 
and  have  also  been  used  to  a  small  extent  as  linings  for  Portland-cement 
kilns. 

Manufacture  of  magnesia  bricks. — In  discussing  the  methods  and 
effects  of  calcining  magnesite  it  was  stated  that  two  different  forms 
of  magnesia  could  be  obtained,  according  to  the  temperature  at 
which  the  calcination  is  carried  on.  If  the  magnesite  be  burned 
at  a  light-red  heat,  the  resulting  magnesia  will  have  a  low  specific 
gravity  (3.00  to  3.07),  will  possess  sufficient  plasticity  to  be  capable 
of  being  molded  into  shapes,  and  will  gradually  absorb  water  and 
carbon  dioxide  from  the  atmosphere,  just  as  quicklime  would  do.  The 
result  of  this  absorption  is  that  this  form  of  magnesia  will  finally  become 
partly  recarbonated. 

If  the  calcination  takes  place  at  a  higher  temperature,  however 
the  resulting  magnesia  will  be  heavy,  with  a  specific  gravity  of  3.61 
to  3.80;  it  will  be  absolutely  devoid  of  plasticity;  and  it  will  not  recar- 
bonate  on  exposure  to  the  atmosphere. 

These  differences  in  the  physical  and  chemical  properties  of  the 
two  forms  of  magnesia  are  taken  advantage  of  in  the  manufacture  of 
magnesia  bricks.  Each  contributes  certain  good  qualities  to  the  brick. 

Magnesia  bricks  are  made  of  a  mixture  of  the  two  forms  of  mag- 
nesia, in  the  proportions  of  four  to  six  parts  heavy  magnesia  to  one 

160 


MAGNESIA  BRICKS  AND  OXYCHLORIDE  CEMENTS. 


161 


part  light  magnesia.  The  dense,  chemically  stable  "  heavy  magnesia  " 
is  thus  the  base  of  the  brick;  the  light  magnesia  is  added  to  give  plas- 
ticity to  the  mixture,  enabling  it  to  be  molded,  and  also  to  harden  on 
exposure  to  the  atmosphere. 

From  10  to  15  per  cent  of  water  is  added  to  this  mixture,  and  the 
resulting  stiff  paste  is  pressed  into  form  in  iron  molds.  The  brick  will 
gradually  harden  on  simple  exposure  to  the  air,  after  which  it  is  usually 
made  still  more  resistant  by  reburning  at  a  low  red  heat.  Bricks  or 
other  objects  made  in  this  manner  may,  if  not  sufficiently  solid  for 
the  use  for  which  they  are  intended,  be  hardened  by  dipping  into  a 
cold  dilute  solution  of  boracic  acid  in  water.  After  this  they  should 
be  dried  and  reburned. 

Composition  of  magnesia  bricks. 

TABLE  66. 
ANALYSES  OF  MAGNESIA  BRICKS. 


1. 

2. 

3. 

4. 

5. 

6. 

Silica  (SiO2)           

0  35 

3  45 

3  10 

3  4 

3  2 

2  16 

Alumina  (A12O3)          

1  30 

JO  98 

0  69 

} 

Iron  oxide  (Fe2O.,)  

6  05 

7  60 

Je.64 

151 

0  3 

JO.  72 

Lime  (CaO)     

2  10 

3  90 

3  76 

2  8 

1  9 

4  20 

Magnesia  (MgO)       

91  52 

83  00 

86  50 

87  8 

93  88 

93  93 

Carbon  dioxide  (CO2)        

0  04 

0  14 

1.  Brick  made  from  Hungarian  magnesite.     Mineral  Industry,  vol.  10,  p.  439. 


Styrian 
Grecian 


Trans.  Am.  Inst.  Min.  Engrs.,  vol.  26,  p.  268. 
Mineral  Industry,  vol.  10,  p.  439. 

Trans.  Am.  Inst.  Min.  Engrs.,  vol.  26,  p.  268. 


Physical  praperties  of  magnesia  bricks. — The  brick  *  whose  analysis 
is  given  in  column  3  of  Table  66  was  made  in  Pittsburg  from  Styrian 
magnesite.  Its  specific  gravity  was  3.44,  equivalent  to  a  weight  of 
160.9  Ibs.  per  cubic  foot.  The  brick  whose  analysis  appears  in  column  6 
of  the  same  table  was  made  from  Grecian  magnesite.  Its  specific  gravity 
was  3.54,  corresponding  to  a  weight  of  170.2  Ibs.  per  cubic  foot. 

Le  Chatelier  tested  two  kinds  of  magnesite  bricks  (Austrain  and 
Grecian)  for  expansion  with  increase  of  temperature,  obtaining  the 
results  quoted  in  Table  67.  The  expansions  given  are  in  millimeters, 
for  a  bar  100  mm.  in  length,  and  are  therefore  equivalent  to  percent- 
ages. 


*  Trans.  Am.  Inst.  Min.  Engrs.,  vol.  26,  p.  268. 


162 


CEMENTS,  LIMES,  AND  PLASTERS. 


TABLE  67. 
EXPANSION  OP  MAGNESITE  BRICKS  ON  HEATING.     (LE  CHATELIER.) 


200°  C. 

400°  C. 

600°  C. 

800°  C. 

Austrian  magnesite  brick       ....        

mm. 

0  21 

mm. 
0   55 

mm. 

0  85 

mm. 
1  10 

Grecian  magnesite  brick         '.  <  * 

»    0  25 

0  52 

0  79 

1   02 

References  on  magnesite  bricks. — The  following  papers  contain  data 
regarding  the  manufacture  and  properties  of  magnesia  bricks. 

Bischof,    C.     On   magnesia   bricks.     Proc.    Inst.    Civil    Engineers,    vol.    112, 

pp.  381-383.     1893. 

Egleston,   T.     Basic  refractory  materials.    Trans.   Amer.   Inst.  Mining  En- 
gineers, vol.  4,  pp.  455-492.     1876. 
Pennock,  J.  D.     Laboratory  note  on  the  heat-conductivity,  expansion,  and 

fusibility  of  firebrick.    Trans.  Amer.  Inst.  Mining  Engineers,  vol.  26, 

pp.  263-269. 
Percy,  J.    Magnesia  crucibles  and  bricks.    Metallurgy,  vol.  1,  pp.  134-137. 

1875. 
Vlasto,  S.   J,     The  magnesite   industry.    Engineering  and  Mining  Journal, 

March  10,  1900. 

Weiss,  N.     Magnesite  in  Hungary.     Iron  Age,  Jan.  15,  1903,  pp,  20-21. 
Anon.     Magnesite  [and  magnesia  brick].     Mineral  Industry,  vol.  10,  pp.  438- 

439.     1902. 

Oxychloride  Cements. 

In  1853  the  chemist  Sorel  discovered  that  zinc  chloride,  when  mixed 
with  zinc  oxide,  united  with  it  to  form  a  very  hard  cement.  Later  it 
was  discovered  that  the  same  held  true  of  a  mixture  of  magnesium 
chloride  and  magnesia.  The  product  in  both  cases  is  the  same — an 
oxychloride  of  zinc  or  magnesium  respectively.  Chlorides  and  oxides 
of  several  other  elements  possess  this  same  property,  but  it  has  been 
utilized  commercially  only  in  the  cases  of  the  zinc  and  magnesium  com- 
pounds. Of  these,  zinc  oxychloride  is  extensively  used  as  a  stopping 
by  dentists.  Magnesium  oxychloride,  called  commonly  Sorel  cement 
or  magnesia  cement,  has  more  important  technical  uses. 

SoreFs  magnesia  cement  is  made  by  mixing  calcined  magnesia  with 
a  solution  of  magnesium  chloride  of  25°  or  30°  Baume.  If  the  magnesia 
has  been  prepared  from  magnesite,  it  usually  contains  a  little  residual 
carbon  dioxide  (C02),  and  though  setting  very  rapidly  and  giving  a 
very  strong  cement,  cracks  are  apt  to  develop  during  setting.  When 


MAGNESIA  BRICKS  AND  OXYCHLORIDE   CEMENTS.  163 

made  from  magnesium  chloride  (see  p.  158)  the  magnesia  is  free  from 
carbon  dioxide,  and  though  it  sets  and  hardens  less  rapidly,  no  cracks 
appear. 

The  commercial  magnesium  chloride  used  in  the  preparation  of 
Sorel  stone,  etc.,  usually  contains  sulphuric  acid.  As  this  acid  and 
its  compounds  spoil  the  appearance  and  the  durability  of  the  stone 
produced,  it  is  eliminated  from  the  magnesium  chloride  by  treatment 
with  barium  hydrate  or  barium  carbonate.  In  practice,*  the  magnesium 
chloride  is  dissolved  in  water  to  form  a  solution  of  20°  to  25°  Eaume, 
and  the  barium  hydrate  or  carbonate  is  added  by  degrees  and  carefully 
stirred  until  the  precipitate  of  barium  sulphate  ceases  to  increase.  The 
amount  of  reagent  required  is  usually  between  6  and  10  per  cent  of 
the  weight  of  the  magnesium  chloride  treated. 

Magnesia  cement  is  used  very  extensively  f  as  a  binder,  in  connection 
with  briquetting,  in  the  manufacture  of  artificial  building-stones,  tiles, 
grindstones,  and  emery-  and  polishing-wheels.  Its  binding  quality  is 
very  considerable,  and  it  is  very  plastic  and  cheap.  A  good  mixture 
for  this  use  consists  of  25  parts  of  magnesium  chloride  (45  per  cent 
solution),  25  parts  magnesia  (93  per  cent  MgO),  and  50  parts  water. 
About  5  Ibs.  of  this  mixture  will  serve  to  cement  95  parts  of  stone, 
emery,  etc.  The  resulting  blocks  are  very  solid  and  harden  thoroughly 
within  a  few  hours. 

Gillmore,  in  1871,  prepared  a  report  on  certain  American  patented 
products  based  upon  Sorel  cements.  As  this  report  is  still  the  only 
complete  discussion  of  the  subject  it  is  reprinted  below,  almost  verbatim. 

"The  several  steps  in  the  process,  beginning  with  the  raw  magne- 
site,  are  briefly  as  follows,  viz. : 

"First.  The  magnesite  is  burnt  in  ordinary  lime-kilns,  at  a  dark 
cherry-red  heat,  for  about  twenty-four  hours.  The  result  is  protoxide 
of  magnesium,  which  is  next  ground  to  fine  powder  between  horizonta' 
millstones,  furnishing  what  .the  Union  Stone  Company  style  ' Union 
cement'. 

"Magnesite  has  been  procured  from  various  localities.  That  from 
Greece,  California,  Maryland,  and  Pennsylvania  contains  about  95 
per  cent  of  carbonate  of  magnesia,  the  residue  being  mostly  insoluble 
silicious  matter.  The  burnt  product  is  perfectly  white.  A  magnesite 
is  procured  in  Canada  which  contains  from  60  to  85  per  cent  of  car- 

*  Journ.  Soc.  Chem.  Industry,  vol   21,  p.  257.     1902. 

t  Schorr,  R.  The  briquetting  of  minerals.  Eng.  and  Mining  Journal,  vol.  74, 
p.  673.  1902. 


164  CEMENTS,  LIMES,  AND  PLASTERS. 

bonate  of  magnesia.  A  variable  percentage  of  iron  in  the  residue  gives 
the  cement  derived  from  this  stone  a  reddish  tint. 

"Second.  For  making  stone,  the  burnt  and  ground  magnesite 
(oxide  of  magnesium)  is  mixed  dry  in  the  proper  proportion  with  the 
material  to  be  united;  that  is,  with  powdered  marble,  quartz,  emery, 
silicious  sand,  soapstone,  or  with  whatever  substance  forms  the  basis 
of  the  stone  to  be  imitated  or  reproduced. 

"The  usual  proportions  a'rei.for  enaery- wheels,  10  to  15  per  cent  of 
oxide  of  magnesium  by  weight;  for  building-blocks,  such  as  sills,  lintels, 
steps,  etc.,  6  to  10  per  cent,  and  for  common  work  for  thick  walls,  less 
than  5  per  cent.  K 

"The  dry  ingredients  are  mixed  together  by  hand  or  in  a  mill.  A 
hollow  cylinder  revolving  slowly  about  its  axis  would  answer  the  pur- 
pose. 

"Third.  After  this  mixing  they  are  moistened  with  chloride  of 
magnesium,  for  which  bittern  water — the  usual  refuse  of  seaside  salt- 
works—is a  cheap  and  suitable  substitute.  The  moistened  material 
is  then  passed  through  a  mill,  which  subjects  it  to  a  kind  of  trituration, 
by  which  each  grain  of  sand  or  other  solid  material  becomes  entirely 
coated  over  with  a  thin  film  of  the  cement,  formed  by  a  combination  of 
the  chloride  with  the  oxide  of  magnesium.  The  bittern  water  is  required 
to  be  of  the  density  of  from  15°  to  30°  Baume.  The  mass  on  emerging 
from  the  mill  should  be  about  as  moist  as  molder's  clay.  The  mixing- 
machine  used  by  the  Union  Stone  Company  is  an  improved  pug-mill 
invented  by  Mr.  Josiah  S.  Elliott.  It  is  represented  as  an  excellent 
mill,  doing  its  work  thoroughly. 

"Fourth.  The  mixture  is  formed  into  blocks  by  ramming  or  tamping 
it  in  strong  molds  of  the  required  form,  made  of  iron,  wood,  or  plaster, 
precisely  as  described  in  paragraph  24,  Report  on  Beton  Agglomere. 
The  block  may  be  taken  out  of  the  mold  at  once  and  nothing  further 
need  be  done  to  it.  The  setting  is  progressive  and  simultaneous  through- 
out the  mass,  as  with  other  hydraulic  cements,  and  requires  from  one 
hour  to  one  day,  depending  somewhat  on  the  chemical  properties  of 
the  solid  ingredients  used,  the  carbonates  as  a  rule  requiring  a  longer 
time  than  the  silicates. 

11  Building-blocks  will  bear  handling,  and  may  be  used  when  three 
or  four  days  old,  although  they  do  not  attain  their  maximum  strength 
and  hardness  for  several  months.  Emery-wheels  are  not  allowed  to  be 
used  in  less  than  four  weeks. 

"This  stone  so  closely  resembles  the  natural  stone,  whether  marble, 
soapstone,  sandstone,  etc.,  from  which  the  solid  ingredients  are  ob- 


MAGNESIA  BRICKS  AND   OXYCHLORIDE  CEMENTS.  165 

tained  by  crushing  and  grinding,  that  it  is  difficult,  without  the  appli- 
cation of  chemical  tests,  to  detect  any  difference  in  either  texture, 
color,  or  general  lithological  appearance. 

"Strength. — In  strength  and  hardness  this  stone  greatly  surpasses 
all  other  known  artificial  stones,  and  is  equaled  by  few,  if  any,  of  the 
natural  stones  that  are  adapted  to  building  purposes.  The  artificial 
marble  takes  a  high  degree  of  polish,  being  in  this  respect  fully  equal  to 
the  best  Italian  varieties. 

"Some  trials  of  2-inch  cubes  at  the  Boston  Navy-yard  gave  the 
following  results,  reduced  to  the  crushing  pressure  upon  one  square  inch: 

No.  1,  crushing  strength  per  square  inch 7,187^  Ibs. 

No.  2,         "  " 11*5621  " 

No.  3,         "  "        "         "   21,562*  " 

No.  4,  " 7,343 J  " 

"  In  none  of  these  samples  did  the  proportion  of  the  oxide  of  mag- 
nesium exceed  15  per  cent  by  weight  of  the  inert  material  cemented 
together.  This  statement  is  derived  from  the  treasurer  of  the  company. 

"  The  principal  business  of  the  Union  Stone  Company  up  to  the  present 
time  has  been  the  manufacture  of  emery-wheels.  The  great  tensile 
strength  of  the  material  may  be  inferred  from  the  fact  that  in  the  proof 
trials  the  wheels  are  made  to  revolve  with  a  velocity  of  from  2  to  3  miles 
per  minute  at  the  circumference.  They  do  not  usually  begin  to  break 
until  a  velocity  of  from  4  to  5  miles  per  minute  is  attained. 

"From  a  number  of  specimens  of  this  stone  furnished  the  writer 
by  the  treasurer  of  the  company,  who  also  gave  their  age  and  com- 
position as  reported  below,  comprising  coarse  and  fine  sandstone  of 
various  shades  of  color,  hones,  white  and  variegated  marble,  emery- 
wheels,  billiard-balls,  concrete  building-blocks,  etc.,  some  small  blocks 
were  prepared  and  subjected  to  crushing  with  the  results  given  in 
Table  68. 

"Durability. — The  proofs  of  the  durability  of  the  Union  stone  rests 
upon  other  evidence  than  that  furnished  by  severe  and  prolonged  climatic 
exposure.  In  Boston,  however,  building-blocks  have  resisted  two  winters, 
and  at  the  present  time  appear  to  be,  and  doubtless  are,  harder  and 
stronger  than  before  they  were  touched  with  frost. 

"Dr.  C.  T.  Jackson,  State  Assayer  of  Massachusetts,  reports  upon 
it  as  follows: 

"'I  find  that  the  frost  test  (saturated  solution  of  sulphate  of  soda) 
has  not  the  power  of  disintegrating  it  in  the  least.  The  trial  was  made 
by  daily  immersions  of  the  stone  in  the  sulphate-of-soda  solution  for  a 
week  and  allowing  the  solution  to  penetrate  the  stone  as  much  as  pos- 


J66 


CEMENTS,  LIMES,  AND  PLASTERS. 


TABLE  68. 
COMPRESSIVE  STRENGTH  OF  SOREL  STONE. 


Character  of  the  Inert 
Materials. 

Proportion  by 
Weight  of 
Oxide  of 
Magnesium. 

Age  of 
Blocks. 

Size  of  Blocks. 

Total 
Crushing 
Strength. 

Crushing 
Strength 
per 
Square 
Inch. 

1    Coral  sand        

Per  Cent. 
12 
12  to  15 

Not  known 
15 
12  to  13 
12 

Not  known 

1  year    f* 
1     " 

2  years 
3      " 

9  months 
2  years 

Not  known 

2"  X2i"Xl$" 
lf"X2"  Xlf" 

lf"X2"  Xl|" 

ii"xii"xii" 

H"x2"  xu" 

lf"X2"  Xli" 
U"Xli"Xl" 

Lbs. 

26,500 
20,000 

54,000 
26,000 
23,000 
16,000 

12,000 

Lbs. 

6,235 
7,272 

19,636 
11,555 
6,133 
4,923 

7,680 

2.  Pulverized  quartz   . 
3.  Washed    flour    of 
emery  (a  piece  of 
hone)             

4.  Fine  marble  
5.  Mill-sweepings  
6.  Marble  and  sand.  .  . 
7.  Marble  with  colored 
veneer  

sible  and  then  to  crystallize.  From  this  test  it  is  evident  that  your 
stone  will  withstand  the  action  of  frost  more  perfectly  than  any  sand- 
stone or  ordinary  building  stone  now  in  use.  I  see  no  reason  why  it 
will  not  stand  as  well  as  granite/ 

"  PL  perfect  resistance  to  the  freezing  and  thawing  of  one  winter  may 
safely  be  accepted  as  conclusive  evidence  of  the  durability  in  the  open 
air  of  an  artificial  stone  of  which  the  matrix  is  any  kind  of  hydraulic 
cement.  At  no  subsequent  period  will  it  be  as  likely  to  fail,  from  freezing 
and  thawing,  as  during  the  first  winter.  A  stone  suitable  for  all  kinds 
of  building  purposes  on  land  might,  however,  fail  under  the  solvent 
action  of  sea-water.  On  this  head  it  can  be  said  that  magnesian  com- 
pounds are  understood  to  resist  the  immersion  in  the  sea  better  than 
the  compounds  of  alumina  or  lime. 

"For  these  reasons  this  new  stone  has,  with  some  exceptions,  been 
limited  in  its  application  to  articles  of  small  bulk  and  great  comparative 
value,  for  which  other  approved  and  less  expensive  artificial  stone  is 
either  not  suitable  or  of  less  practical  value.  Although  for  architectural 
ornaments  of  elaborate  design  it  is  perhaps  less  costly,  even  now,  than 
granite  or  marble,  it  cannot  hope  to  compete  successfully  for  general 
adoption  and  use  by  engineers  and  architects  with  the  beton  agglomere 
and  the  softer  kinds  of  natural  stone  until  the  market  price  of  the  oxide 
of  magnesium  is  greatly  reduced.  For  the  peculiar  purposes  to  which  it 
is  adapted,  it  supplies  what  has  heretofore  been  felt  as  a  great  want, 
and  in  this  field,  which  is  neither  narrow  nor  unvaried,  it  has  no  prominent 
rival. 


MAGNESIA  BRICKS  AND  OXVCHLORIDE  CEMENTS.  167 

"The  following  formula  has  been  found  suitable  for  window-caps, 
sills,  steps,  etc.  The  quantities  specified  will  make  1  cubic  foot  of 
stone. 

100  pounds  of  beach  sand,  cost  $1.00  per  ton  at  the  works $0.05 

10  of  comminuted  marble,  cost  $5.00  per  ton  at  the  works 0.02J 

10       "       of  Union  cement  (oxide  of  magnesium) o  50 

10       "       of  chloride  of  magnesium  in  solution,  20°  Baum6 f  02 

130       ' '       yielding  1  cubic  foot  of  molded  stone $0 . 59 % 

"The  labor,  depending  somewhat  on  the  design  as  regards  the  degree 
and  character  of  its  ornamentation,  will  vary  per  cubic  foot  from  20 
to  25  cents,  making  total  cost  of  1  cubic  foot  of  finished  building-block 
79^  to  84 J  cents.  This  price  may  be  reduced  10  to  15  cents  per  cubic 
foot  by  incorporating  large  pebbles  and  small  cobble-stones  during 
the  process  of  molding. 

"For  foundations  and  other  plain,  massive  walls,  the  proportion 
of  cement  may  be  very  considerably  reduced  and  the  quantity  of  cobble- 
stones increased." 

References  on  oxychloride  cements,  Sorel  stone,  etc. 

Ebel  [Magnesia  cement  concrete  for  use  in  mines].  Zeits.  angew.  Chemie, 
vol.  15,  p.  44.  Abstract  in  Journ.  Soc.  Chem.  Industry,  vol.  21,  p.  175. 
1902. 

Gillmore,  Q.  A.  Practical  treatise  on  Coignet-Beton  and  other  artificial 
stone.  1871. 

Luhmann,  E.  Magnesia  cement.  Chem.  Zeitung,  vol.  25,  Report  345.  Ab- 
stract in  Journ.  Soc.  Chem.  Industry,  vol.  21,  p.  118.  1902. 

Preussner,  L.  Magnesia  cement.  Thonindustrie  Zeitung,  vol.  25,  p.  2115. 
Abstract  in  Journ.  Soc.  Chem.  Industry,  vol.  21,  p.  257.  1902. 

Schorr,  R.  The  briquetting  of  minerals.  Engineering  and  Mining  Journalt 
vol.  74,  p.  673.  Nov.  22,  1902. 


PART  IV.     HYDRAULIC  LIMES,  SELENITIC  LIME, 
AND  GRAPPIE.R  CEMENTS. 


CHAPTER  XIII. 
THE  THEORY  OF  HYDRAULIC  LIMES. 

BEFORE  taking  up  the  manufacture  and  properties  of  the  various 
'Closely  allied  products — hydraulic  limes,  selenitic  limes,  and  grappier 
cements — which  are  to  be  discussed  in  this  part  of  the  volume,  it  seems 
desirable  to  devote  some  space  to  a  consideration  of  the  general  principles 
-on  which  the  manufacture  and  use  of  these  products  are  based. 

The  materials  heretofore  discussed  in  this  volume — the  plasters, 
common  lime,  magnesia,  etc. — have  been  simple  in  both  composition 
and  action.  With  the  hydraulic  limes,  however,  we  take  up  the  first 
member  of  a  great  class  of  very  complex  products.  All  these  products 
possess  hydraulic  properties.  In  composition,  they  further  agree  in 
that  they  all  consist  essentially  of  silica,  alumina,  and  lime,  with  or 
without  magnesia  and  iron  oxide.  This  group  of  complex  cementing 
materials  includes  the  hydraulic  limes,  the  natural  cements,  the  Port- 
land cements,  and  the  puzzolan  cements.  These  four  classes  are  quite 
distinct  commercially,  but  it  is  at  times  difficult  to  draw  the  dividing 
lines  between  the  classes  in  words.  Before  defining  the  class  of 
"hydraulic  limes'7  it  will  therefore  be  well  to  explain  the  principal 
criterion  which  will  be  employed  in  drawing  up  that  definition.  This 
criterion  is  the  " Cementation  Index",  a  more  satisfactory  form  of  the 
older  " hydraulic  index". 

The  "Hydraulic  Index". — In  discussing  the  classification  of  cement- 
ing materials,  in  the  introduction  to  this  volume,  the  statement  is 
made  that  the  power  of  setting  under  water,  possessed  by  the  hydraulic 
limes  and  cements,  is  due  to  the  formation  of  compounds  of  silica,  alu- 
imina,  and  lime  during  the  manufacture  of  the  cementing  materials 

168 


THE  THEORY  OF  HYDRAULIC  LIMES.  169 

in  question.  This  being  the  case,  it  is  a  fair  assumption  *  that  the 
degree  of  hydraulic  activity  and  the  strength  of  any  given  cementing 
material  will  be  related,  in  some  way,  to  the  proportions  in  which  it 
contains  these  ingredients  (silica,  alumina,  lime,  etc.),  and  to  the  man- 
ner in  which  they  are  combined. 

It  is  obvious  that  it  would  be  of  great  value  to  both  manufacturer 
and  engineer  if  we  could  devise  some  method  for  quantitatively  express- 
ing this  relation  between  the  composition  and  the  hydraulic  value  of 
any  given  sample  of  cementing  material.  Several  methods  of  doing 
this  have  been  suggested  and  used  by  various  authorities. 

Of  these  methods  of  expression,  the  one  that  has  come  into  most 
general  use  is  based  upon  the  calculation  of  the  "  hydraulic  index  ". 
The  "  hydraulic  index  ",  as  usually  defined,  is  the  ratio  between  the 
percentage  of  silica  plus  alumina  to  the  percentage  of  lime  (CaO).  A 
hydraulic  lime,  for  example,  such  as  that  from  Metz  (Analysis  No.  2, 
Table  74),  containing  18.47  per  cent  silica,  5.73  per  cent  alumina,  and 
68.19  per  cent  lime  would  therefore  have  for  its  hydraulic  index 

18.47+5.73    24.20 
~~68l9 —  =68T9  (Hydraulic  Index). 

The  "  hydraulic  index  ",  calculated  in  this  manner,  is  then  used 
as  a  basis  for  classifying  cementing  materials  according  to  their  hydraulic 
activity.  The  following  grouping,  which  is  substantially  that  given 
by  Spalding,t  is  an  example  of  this: 

Hydraulic  Index.  Product. 

Less  than  0.10 Common  lime,  quicklime 

0.10  to  0.20 Feebly  hydraulic  limes 

0.20  "  0.40 Eminently  hydraulic  limes 

0.40  "  0.60 Portland  cement  (if  burned  at  high  temperature) 

0.60  "  1.50 Natural  cements 

1.50  "  3.00 Weak  natural  cements 

3.00 Puzzolanas,  etc. 

The  "  hydraulic  index  "  calculated  and  used  in  this  fashion  is 
certainly  better  than  nothing,  but  it  possesses  defects  which  render 
it  valueless  in  dealing  with  certain  classes  of  cements.  These  defects 
arise  chiefly  from  the  facts  that  in  calculating  the  "  hydraulic  index  " 
(1)  no  allowance  is  made  for  the  action  of  either  magnesia  or  iron  oxide, 
and  (2)  the  assumption  is  made  that  silica  and  alumina  are  quanti- 

*  Strictly  speaking,  this  statement  is  based  on  more  than  a  mere  assumption; 
but  as  a  matter  of  convenience  discussion  of  the  reasons  for  it  will  be  deferred 
to  later  chapters. 

fSpalding,  F.  P.     "Hydraulic  Cement",  pp.  8,  31,  38. 


170  CEMEiNTS,  LIMES,  AND  PLASTERS. 

tatively  interchangeable,  i.e.,  that  10  per  cent  of  silica  will  have  exactly 
the  same  effect  as  10  per  cent  of  alumina. 

These  defects  have  led  the  writer  to  abandon  the  use  of  the  "hydraulic 
index  "  and  to  substitute  therefor  the  index  described  in  the  next 
section  as  the  "  Cementation  Index  ". 

The  Cementation  Index. — As  explained  and  defined  below,  the 
Cementation  Index  is  a  natural  outgrowth  from  the  formula  proposed 
by  Newberry  for  proportioning'  Portlatitl-cement  mixtures.  The  index 
now  proposed  differs  from  that  formula  in  assigning  values  for  the 
magnesia  and  iron  oxide  contained  in  the  cement  or  lime,  a  change 
which  is  necessary  in  order  to  adapt  it  for  use  wfth  the  magnesian 
natural  cements  and  the  puzzolan  cements.  The  proposed  index  is: 

(2. 8  x  percentage  silica)  +(1.1  x  percentage  alumina) 

Cementation  Index. ^ +  (.7 xpercentage  iron  oxide) 

(rercentage  lime)+(  1.4  xpercentage  magnesia) 

EXAMPLE. — As  an  example  of  the  details  of  calculating  the  Cementa- 
tion Index,  the  hydraulic  lime  of  Metz,  whose  analysis  is  given  as  No.  2 
of  Table  74,  will  be  used.  The  essential  ingredients  of  this  lime,  as 
given  in  the  quoted  analysis,  are: 

.      Silica  (SiO2) ' 18.47 

Alumina  ( A12O3) 5 . 73 

Iron  oxide  (Fe2O3) -    3.29 

Lime  (CaO) 68 . 19 

Magnesia  (MgO) 2.66 

Substituting  these  values  in  the  formula 

2.8  percentage  silica +  1.1  percentage  alumina 

Cementation  Index=-^- +.7  percentage  iron  oxide 

rercentage  lime +1.4  percentage  magnesia 
we  have 

Cementation  Index =  (2*X18.47)  +(1.1x5.73)  +(7X3.29) 

(68.19) +(1.4X2.66) 
^51.716+6.303  +  2.303 

68.19+3.724 
^60.322 
"71.914 
=  .839. 

As  will  be  seen  later ,_  this  is  a  very  typical  value  for  the  Cementa- 
tion Index  of  a  good  hydraulic  lime. 


THE  THEORY   OF  HYDRAULIC  LIMES.  171 

The  use  of  the  Cementation  Index,  as  here  stated,  involves  certain 
assumptions  as  to  the  constitution  of  hydraulic  cementing  materials. 
These  are,  in  order  of  importance: 

(1)  That  in  hydraulic  limes  and  cements  the  hydraulic  activity  is 
due  to  the   formation   during   manufacture   of  certain   compounds   of 
lime  and  magnesia  with  silica,  alumina,  and  iron. 

(2)  That  the  silica  combines  normally  with  the  lime  in  such  molec- 
ular proportions  as  to  form  the  tricalcic  silicate,  3CaO.SiO2. 

(3)  That  the  alumina  combines  with  the  lime  as  the  dicalcic  alu- 
minate,  2CaO.Al2O3. 

(4)  That  magnesia  is,   molecule  for  'molecule,   equivalent  to  lime 
in  its  action. 

(5)  That  iron  oxide  is,  molecule  for  molecule,  equivalent  to  alumina. 
Of  these  five  assumptions,  the  first  is  simply  a  general  statement 

of  conditions  which  are  recognized  by  everybody  as  probably  existing. 
The  second  assumption,  likewise,  is  generally  accepted,  since  it  agrees 
with  the  views  of  both  Le  Chatelier  and  Newberry.  The  third,  based 
on  Newberry 's  experiments  and  confirmed  by  those  of  Richardson,  is 
practically  accepted  by  all  American  cement  chemists,  though  not  by 
those  who  follow  Le  Chatelier. 

The  fourth  and  fifth  assumptions,  however,  are  open  to  question, 
and  the  writer  realizes  that  serious  objections  may  be  urged  against 
them.  But  he  also  realizes  that  magnesia  and  iron  must  be  accounted 
for  in  some  way,  that  the  assumptions  above  made  are  inherently  prob- 
able, and  that  the  resulting  "  Cementation  Index  "  works  out  very 
well  in  practice.  For  the  present,  therefore,  the  "  Cementation  Index  " 
will  be  accepted  as  a  guide  in  discussing  the  composition  and  the  char- 
acteristics of  the  hydraulic  limes. 

Use  of  the  Cementation  Index  in  classification. — The  Cementation 
Index  will  be  used  in  classifying  the  various  hydraulic  products,  for 
it  gives  information  of  value  concerning  the  properties  of  the  various 
products.  But  it  cannot  be  the'  sole  basis  for  classification,  because 
the  properties  of  a  hydraulic  cementing  material  will  be  later -seen  to 
depend  not  only  on  its  composition,  but  on  the  conditions  of  its  manu- 
facture. A  material  having  a  Cementation  Index  of  1.05  might  be, 
for  example,  a  hydraulic  lime,  a  natural  cement,  or  a  cement  of  the 
Portland  type,  depending  chiefly  on  the  temperature  at  which  the  raw 
material  was  burned.  In  general,  however,  the  possible  variation  is 
by  no  means  so  wide  as  this.  A  material  with  a  Cementation  Index 
of  0.40,  for  example,  could  under  no  possible  temperature  conditions 
yield  anything  but  a  somewhat  weak  hydraulic  lime. 


172  CEMENTS,  LIMES,  AND  PLASTERS. 

In  later  chapters,  when  the  separate  products  are  under  discussion, 
their  respective  Cementation  Indexes  will  be  determined  and  stated. 
At  present  we  are  only  concerned  with  determining  the  limiting  values 
of  this  index  for  the  hydraulic  limes.  As  will  be  seen  from  following 
paragraphs,  these  limits  are  theoretically  very  wide,  but  in  actual  prac- 
tice very  narrow. 

Definition  of  hydraulic  Unties.  — T?he  hydraulic  limes  include  all 
those  cementing  materials  (made  by  burning  siliceous  or  argillaceous 
limestones)  whose  clinker  after  calcination  contains  so  large  a  per- 
centage of  lime  silicate  (with  or  without  lime  alumiaates  and  ferrites) 
as  to  give  hydraulic  properties  to  the  product,  but  which  at  the  same 
time  contains  normally  so  much  free  lime  (CaO)  that  the  mass  of  clinker 
will  slake  on  the  addition  of  water. 

The  commercial  advantage  of  manufacturing  a  material  of  this 
kind  is  that,  while  the  product  has  hydraulic  properties,  yet  its  clinker 
will  slake  and  pulverize  itself  on  the  simple  addition  of  water,  thus  avoid- 
ing the  expensive  mechanical  grinding  required  by  the  clinker  of  natural 
and  Portland  cements. 

The  definition,  therefore,  requires  that  a  material  to  be  called  a 
hydraulic  lime  must  satisfy  two  conditions:  (1)  its  clinker  must  con- 
tain enough  free  lime  to  slake  with  water,  and  (2)  the  resulting  powder 
must  be  capable  of  setting  or  hardening  under  water.  These  two 
requisite  conditions,  in  their  turn,  fix  the  limits  of  lime  that  the  clinker 
may  contain.  The  minimum  amount  of  lime  present  is  obviously 
determined  by  the  consideration  that,  after  burning,  enough  free  lime 
(in  addition  to  that  combined  with  the  silica,  alumina,  and  iron)  must 
be  present  in  the  clinker  to  reduce  the  entire  mass  to  powder  by  the 
force  of  its  own  slaking.  The  maximum  amount  of  lime,  on  the  other 
hand,  is  determined  by  the  commercial  condition  that  no  more  free 
lime  should  be  present  than  is  absolutely  necessary  to  accomplish  this 
pulverization,  for  the  free  lime,  whose  slaking  powders  the  mass,  is  by 
that  same  slaking  made  into  an  inert,  or  at  least  non-hydraulic,  material. 

The  desired  result — the  formation  of  a  clinker  consisting  largely  of 
lime  silicates,  etc.,  but  also  containing  sufficient  free  Ihne  to  slake  readily 
— can  be  attained  in  two  different  ways,  which  yield  products  very 
different  in  quality.  These  two  methods  are: 

(1)  By  the  calcination,  at  a  medium  temperature,  of  a  siliceous  or 
argillaceous  limestone  having  a  Cementation  Index  lying  between  0-30 
and  1.10.  Such  a  limestone  will  carry  so  high  a  percentage  of  calcium 
carbonate  (relative  to  its  content  of  silica,  alumina,  and  iron  oxide) 
as  to  leave,  after  most  of  its  silica,  etc.,  have  been  combined  with  lime, 


THE  THEORY  OF   HYDRAULIC  LIMES.  173 

tfufficient  free  lime  to  slake  the  clinker.  Hydraulic  limes  produced 
in  this  fashion  are  the  typical  hydraulic  limes,  and  the  following  chapters 
will  have  reference  to  such  materials  only.  It  is  possible,  however,  to 
produce  a  hydraulic  lime  by  another  method,  as  above  noted.  This 
second  and  much  less  satisfactory  method  is 

(2)  By  the  calcination,  at  temperatures  too  low  to  permit  perfect 
combination  of  the  silica,  alumina,  and  iron  oxide  with  the  lime,  of  a 
siliceous  or  argillaceous  limestone  (less  rich  in  lime  than  those  employed 
in  the  first  method)  having  a  Cementation  Index  of  1.10  to  1.60  or  over. 
In  other  words,  a  rock  is  used  which  would,  under  proper  conditions  of 
burning,  give  a  good  natural  cement.  If  it  is  burned  at  too  low  a  tem- 
perature to  effect  this,  however,  the  result  will  be  a  hydraulic  lime,  for 
the  clinker  will  consist  partly  of  silicate  and  aluminate  of  lime,  together 
with  notable  amounts  of  free  lime,  free  silica,  and  free  alumina. 
Hydraulic  limes  produced  in  this  way  necessarily  carry  a  very  large 
proportion  of  absolutely  inert  material.  They  are,  in  fact,  simple 
imperfectly  burned  natural  cements  and  will  not  be  discussed  further 
in  this  connection. 

Reverting  to  the  true  hydraulic  limes,  it  has  been  said  above  that 
their  Cementation  Index  may  range  from  0.30  to  1.10;  and  it  will  be 
seen  later  that  commercial  hydraulic  limes  do  occur  with  indexes  a& 
low  as  0.331,  while  others  are  as  high  as  1.06. 

There  is,  however,  considerable  reason  for  dividing  the  true  hydraulic 
limes  into  two  groups,  the  first  or  eminently  hydraulic  limes  containing 
those  products  whose  index  lies  between  0.70  and  1.10;  while  the  second 
group,  or  feebly  hydraulic  limes,  contains  products  whose  Cementation 
Index  ranges  from  0.70  down  as  low  as  0.30.  Commercial  as  well  as- 
theoretical  differences  serve  to  separate  the  two  groups,  and  for  that 
reason  they  will  be  discussed  in  separate  chapters.  Curiously  enough, 
each  of  the  two  classes  has  an  attendant  secondary  product  to  be  con- 
sidered. The  eminently  hydraulic  limes  during  their  calcination  pro- 
duce a  by-product  (grappiers)  which  is  usually  marketed  separately 
as  a  "  grappier  cement".  The  feebly  hydraulic  limes  on  the  other  hand 
are  often  treated  with  sulphuric  acid  m  such  a  way  as  to  develop  new 
properties,  and  are  then  marketed  as  selenitic  limes.  In  further  dis- 
cussion of  the  hydraulic  limes,  therefore,  they  will  be  treated  as  two 
groups  in  two  separate  chapters,  covering  respectively 

Chapter  XIV.     Eminently  Hydraulic  Limes :  Grappier  Cements. 

Chapter  XV.    Feebly  Hydraulic  Limes:  Selenitic  Limes. 


CHAPTER  XIV. 
EMINENTLY  HYDRAULIC  LIMES:    GRAPPIER  CEMENTS. 

THE  hydraulic  limes  are  usually,  compared  to.  Portland  or  good 
natural  cements,  only  feebly  hydraulic.  This  fact,  taken  in  connection 
with  the  abundance  of  materials  suitable  for  the  manufacture  of  natu- 
ral cements,  has  prevented  the  introduction  of  hydraulic-lime  manu- 
facture into  the  United  States,  though  in  Europe  the  industry  is  of 
considerable  importance.  No  hydraulic  lime  is  at  present  made  in 
this  country,  nor  is  there  any  prospect  that  the  industry  will  ever  be 
taken  up  here.  A  considerable  amount  of  hydraulic  lime  and  grappier 
cement  is,  however,  annually  imported.  This  is  brought  about  by 
the  fact  that  these  products,  being  low  in  iron  and  soluble  salts,  are 
light  colored  :and  do  not  stain  masonry.  There  is  thus  a  fair  market 
for  them  for  architectural  rather  than  for  engineering  uses.  A  promi- 
nent brand  of  grappier  cement  much  used  in  the  United  States  as  a 
"  non-staining  cement  "  is  called  Lafarge. 

The  manufacture  and  properties  of  the  hydraulic  limes  and  grappier 
cements  will  be  discussed  briefly.  This  discussion  will  be  practically 
confined  to  the  practice  followed  at  Teil,  France,  where  the  largest 
and  best-known  plants  are  located. 

Composition  of  the  ideal  hydraulic  lime. — The  clinker  of  an  ideal 
hydraulic  lime  should,  as  may  be  deduced  from  the  considerations  set 
forth  in  the  preceding  chapter,  satisfy  two  limiting  conditions.  On 
the  one  hand,  it  must  contain  sufficient  free  lime  to  disintegr  te  the 
entire  mass  of  clinker  by  the  force  of  its  own  slaking.  On  the  other 
hand,  no  more  free  lime  should  be  present  than  is  absolutely  necessary 
to  effect  this  disintegration;  and  no  uncombined  silica  or  alumina 
should  be  present  in  the  clinker.  This  ideal  condition  would  be  arrived 
at,  according  to  Le  Chatelier,*  if  we  could  obtain  a  clinker  containing 
four  equivalents  of  lime  for  one  of  silica.  Three  of  the  four  equiva- 
lents of  lime  would  be  united  with  all  the  silica  to  form  tricalcic  sili- 
cate, while  the  fourth  equivalent  of  lime  would  remain  free,  and  would 

*  Trans.  Am.  Inst.  Min.  Eng.,  vol.  22,  p.  16. 

174 


EMINENTLY  HYDRAULIC  LIMES:  GRAPPIER  CEMENTS.          175 


be  sufficient  to  accomplish  the  disintegration  of  the  entire  mass,  through 
the  force  produced  during  its  own  slaking.  Accepting  this  statement, 
we  can  calculate  the  percentages  of  the  various  constituents  which 
should  be  present  in  an  ideal  hydraulic  lime,  both  before  and  after 
slaking,  and  also  the  composition  of  the  limestone  necessary  to  give, 
in  burning,  this  ideal  product.  The  results  of  such  a  calculation  are 
shown  in  the  following  table. 

TABLE  69. 
COMPOSITION  OF  IDEAL  HYDRAULIC  LIMESTONE  AND  HYDRAULIC  LIME. 


Hydraulic  Lime. 

Hydraulic 

Before  Burning. 

Before 

After 

Slaking. 

Slaking. 

Si02.  . 

13.20 

21.20 

19.08 

CaO  
C02  
H26  

1    86.8        | 
0.00 

78.80 
0.00 
0.00 

70.92 
0.00 
10.00 

100.00 

100.00 

100.00 

Index.  .  .  . 

0.753 

0.753 

0.753 

In  actual  practice,  however,  it  is  found  that  these  theoretical  com- 
positions cannot  be  worked  up  to  advantageously.  If,  for  example,  a 
limestone  of  the  composition  given  -above  (Si(>2  13.2  per  cent,  CaCOs 
86.8  per  cent)  is  burned  under  the  ordinary  conditions  of  hydraulic-lime 
manufacture,  it  is  found  that  all  the  silica  does  not  combine  with  three 
fourths  of  the  lime,  as  is  required  by  the  theory.  What  actually  hap. 
pens  is  that  part  of  the  silica  will  combine  w4th  part  of  the  lime  to 
form  tricalcic  silicate,  thus  leaving  a  certain  amount  of  uncombined 
silica  and  entirely  too  much  uncombined  lime.  Any  increase  in  the 
uncombined  lime  beyond  the  amount  necessary  to  cause  the  clinker  to 
disintegrate  by  its  slaking  lessens  the  hydraulic  value  of  the  product. 

It  is  therefore  necessary,  in  practice,  to  modify  the  ideal  compositions, 
these  modifications  being  in  the  following  directions: 

(a)  Lower  lime  content.  The  limestones  in  actual  use,  as  shown 
by  the  analyses  quoted  in  Tables  70  and  71,  differ  from  the  ideal 
hydraulic  limestone  in  carrying  from  70  to  80  per  cent  of  lime  carbonate 
in  place  of  the  86.8  per  cent  of  theory.  This  lowering  in  the  original 
lime  carbonate  content  of  the  limestones  decreases  the  amount  of  uncom- 
bined lime  in  the  product. 

(6)  Presence  of  alumina  and  iron.  Even  the  best  hydraulic  lime- 
stones in  actual  use  carry  notable  amounts  of  alumina  and  iron  oxide. 


176 


CEMENTS,  LIMES,  AND  PLASTERS. 


These  constituents  act  as  fluxes,,  facilitating  the  combination  of  the 
silica  and  lime.  They  also  combine  themselves  with  lime  to  form 
aluminates  and  ferrites  of  lime.  These  latter  salts  do  not  increase 
the  hydraulic  value  of  the  product,  for  they  become  hydrated  and  inert 
during  the  process  of  slaking,  but  their  formation  disposes  of  some  of 
the  excess  of  free  lime. 

The  effect  of  these  modifications  is  shown  clearly  when  the  Cementa- 
tion Indexes  of  the  ideal  and  the  various'  commercial  products  are  com- 
puted and  compared.  Le  Chatelier's  ideal  lime  has  a  Cementation 
Index  of  0.75,  while  the  actual  limes  whose  analyses  are  given  later 
will  average  about  0.85. 

Analyses  of  a  number  of  commercial  hydraulic  limes  are  given  in 
Table  74,  page  179. 

Raw  materials:  hydraulic  limestones. — The  limestones  actually 
used  in  the  manufacture  of  hydraulic  limes  will  carry  from  70  to  80 
per  cent  of  lime  carbonate.  In  hydraulic  limestones  of  the  best  types, 
such  as  are  used  at  Teil,  France,  the  silica  will  vary  between  13  and  17 
per  cent,  while  the  alumina  and  iron  together  rarely  exceed  3  per  cent. 
Several  analyses  of  hydraulic  limestones  are  given  in  Tables  70  and  71. 

TABLE  70. 
ANALYSES  OF  HYDRAULIC  LIMESTONES,  TEIL,  FRANCE. 


1. 

2 

3. 

4. 

Silica  (SiO2)  «... 

12.40 

13.75 

16  89 

14  30 

Alumina  (A19O.)                         

0  60 

0  65 

0  81 

0  70 

Iron  oxide  (Fe2O3)              

0  50 

trace 

trace 

0  80 

Lime  (CaO)                    

47  49 

47  00 

45  40 

46  50 

Magnesia  (MgO)         

n   d 

n.  d 

n   d 

n   d 

Carbon  dioxide  (CO2)  .•  

37.31 

36.93 

35.67 

36*54 

1.  Alignole  quarry;   average  of  six  analyses  by  Rivot. 

2.  Gaillant  quarry;   average  of  three  analyses  by  Rivot. 

3.  Tinliere  quarry;  analysis  by  Rivot. 

4.  Lafarge  quarry;  average  of  nine  analyses  by  Rivot. 

TABLE  71. 
ANALYSES  OP  HYDRAULIC-LIME  ROCKS,  FRANCE  AND  GERMANY. 


1. 

2. 

3. 

4. 

Silica  (SiO2)                           

17  00 

11  60 

11  03 

11  20 

Alumina  (  A12O3)           

1  00 

'3  60 

3  75 

5  30 

Iron  oxide  (Fe2O3)          

3.0 

5  07 

4  60 

Lime  (CaO) 

44  80 

42  84 

43  02 

35  50 

Magnesia  (MgO) 

0  71 

1  43 

1  34 

5  85 

Carbon  dioxide  (CO2)                           

35  99 

35  23 

35  27 

34  35 

1.  Senonches,  France.     Descotils,  analyst. 

2.  Metz,  Germany.     Berthier,  analyst. 

3.  Hausbergen,  Germany.     Muspratt,  analyst. 

4.  Plassac,  France.     Vicat,  analyst. 


Quoted    by    Zwick,    "Hydraulischer  Kalk    und 
Portland-Cement",  pp.   66,  67. 


EMINENTLY   HYDRAULIC  LIMES:  GRAPPIER  CEMENTS.         177 


TABLE  72. 

ANALYSES  OF  THE  VARIOUS  BEDS  IN  THE  HYDRAULIC  LIMESTONE  QUARRIES  AT 

MALAIN,  FRANCE. 


1. 

2. 

3. 

4. 

5. 

6. 

7. 

8. 

9. 

14.70 
0.60 

45.05 
0.30 

39.35 

Silica  (SiO2)  

7.60 
0.75 

50.05 
0.30 

41.30 

10.15 
0.90 

48.05 
0.30 

40.60 

10.30 
0.65 

48.30 
0.30 

40.45 
0.739 

12.30 
1.00 

46.90 
0.25 

39.55 

15.70 
1.10 

44.75 
0.20 

38.25 

13.80 
0.80 

46.30 
0.25 

38.85 

14.20 
0.85 

45.75 
0.40 

38.80 

14.25 
0.75 

45.35 
0.40 

39.25 

Alumina  (A12O3)  \ 
Iron  oxide  (Fe  O3)              J 

Lime  (CaO) 

Magnesia  (MgO) 

Carbon  dioxide  (CO2).  .  .    1 
Water  J 

Cementation  Index. 

10. 

11. 

12. 

13. 

14. 

15. 

16. 

17. 

18. 

6.40 
0.45 

51.05 
0.45 

41.65 

Silica  (SiO2)           

14.75 
1.05 

45.15 
0.15 

38.90 

16.35 
1.00 

43.85 
0.55 

38.25 
1.05 

16.10 
0.80 

44.20 
0.40 

38.50 

16.80 
0.30 

44.60 
0.40 

37.90 

14.90 
0.80 

45.10 
0.45 

38.75 

14.35 
0.80 

45.55 
0.40 

38.90 

12.45 
0.70 

46.80 
0.45 

39.60 

14.85 
0.75 

45.15 
0.45 

38.80 

Alumina  (A12O3)   \ 

Iron  oxide  (Fe2O3)  J 

Lime  (CaO)  

Magnesia  (MgO)  
Carbon  dioxide  (CO2).  .  .  \ 
Water  J 

Cementation  Index   

Burning. — Hydraulic  lime  is  burned  in  continuous  kilns,  like  common 
lime.  No  difference,  in  fact,  exists  between  the  burning  of  common 
and  of  hydraulic  limes,  so  far  as  the  practical  operations  involved  are 
concerned.  The  temperature  attained  in  burning  is,  however,  higher 
in  hydraulic  lime-kilns  than  in  those  burning  common  lime,  and  the 
fuel  requirements  are  correspondingly  increased.  Beekwith  states, 
for  example,  that  at  Teil  100  tons  of  coal  are  required  to  burn  stone 
equivalent  to  500  tons  of  screened  lime.  This  corresponds  to  a  fuel 
consumption  of  20  per  cent  by  weight  on  the  lime  production. 

The  temperature  and  thoroughness  of  the  burning  are  directly  related 
to  the  Cementation  Index  of  the  lime.  The  higher  the  index  the  less 
care  will  be  necessary  to  avoid  the  presence  of  too  much  free  lime.  A 
hydraulic  lime  of  index  0.75,  for  example,  would  be  much  more  difficult 
to  burn  properly  than  one  whose  index  ran  as  high  as  0.85  or  so.  In 
fact,  as  the  index  approaches  1.00,  the  difficulty  is,  not  to  avoid  free 
lime,  but  to  keep  enough  free  lime  in  the  product  to  enable  it  to  slake 
properly. 

In  Tables  73  and  74  are  given  the  analyses  of  a  number  of  hydraulic 
limes,  after  being  burned  but  before  slaking. 


178 


CEMENTS,  LIMES,  AND  PLASTERS. 


FIG.  27. — Kiln  used  for  burning  hydraulic  lime,  Malain,  France.     (After  Bonnami.) 


EMINENTLY  HYDRAULIC  LIMES:  GRAPPIER  CEMENTS. 


179 


TABLE  73. 
ANALYSES  OF  HYDRAULIC  LIME  BEFORE  SLAKING  (TEIL,  FRANCE). 


1. 

2. 

3. 

4. 

5. 

6. 

7. 

8. 

9. 

Silica  (SiO2) 

20.33 
1.00 

0.82 
77.87 
n.  d. 

.753 

22.39 
1.06 
tr. 
76.55 
n.  d. 

.834 

23.60 
1.28 
tr. 
75.12 
n.  d. 

.898 

22.95 
1.12 
1.28 
74.64 
n.  d. 

.899 

20.57 
1.13 
tr. 
77.76 
0.54 

.749 

21.7 
1.8 
0.6 
74.0 
0.7 

.842 

26  .07 
4.38 
tr. 
68.94 
0.61 

1.115 

26.4 

}3.0 

65.16 
1.04 

1.155 

22.59 

J2.63 
10.84 
65.62 
1.54 

.985 

Alumina  (A12O3) 

Iron  oxide  (Fe2O3)  
Lime  (CaO)    

Magnesia  (MgO)  
Cementation  Index  

1.  Average  of  lime  burned  from  Ahgnole  quarry  rock.  1  Anal  b      Rivot       Quoted   b      Zwick 

3  ..        ....         ..  ..      Tinli>?P        ••         "  "Hydraulischer  Kalk  und  Portland- 

1'          «.        ....         ..  ..       ESSS        ..         ..        j  Cement",  pp.  67,  69. 

5.  Analysis  by  Vicat.     Quoted  by  Beckwith,  "Hydraulic  Lime  of  Teil",  p.  13. 

6.  Quoted  by  Stanger  and  Blount,  Mineral  Industry,  vol.  5,  p.  70. 

7.  Analysis  by  Vicat.     Quoted  by  Beckwith,  "Hydraulic  Lime  of  Teil",  p.  13. 

8.  Analysis  by  Landrin.     Quoted  by  Thorpe,  "Dictionary  Applied  Chemistry",  vol.  1,  p.  483. 

9.  Analysis  by  Michaelis.     Quoted  by  Schoch,  "Mortel-Materialen",  p.  73. 

Two  of  the  above  analyses  of  Teil  lime,  Nos.  7  and  8,  give  exceptionally  high  values  for  the 
Cementation  Index.  The  average  index  of  all  nine  samples  is  0.913;  if  Nos.  7  and  8  be  excluded 
the  average  is  0.85. 

TABLE  74. 
ANALYSES  OF  HYDRAULIC  LIMES,  FRANCE,  GERMANY,  AND  ENGLAND. 


1. 

2. 

3. 

4. 

5. 

e. 

Silica  (SiO2)            

26  77 

18  47 

17  18 

17  75 

23  61 

24  33 

Alumina  (A12O3)      

1.57 

5  73 

5  84 

8  88 

3  89 

3  73 

Iron  oxide  (Fe2O3)  

3  29 

6  32 

6  18 

n  d 

Lime  (CaO)   

70.54 

68.19 

68  56 

56  01 

71  99 

71  94 

Magnesia  (MgO) 

1  12 

2  66 

2  09 

9  28 

0  51 

n  d 

Cementation  Index  

1.06 

.839 

.839 

.925 

.968 

1.00 

1.  Senonches,  France.     Descotils,  analyst. 

2.  Metz,  Germany.     Berthier,  analyst. 

3.  Hausbergen,  Germany.    Muspratt,  analyst. 

4.  Plassac,  France.     Vicat,  analyst. 


Quoted    by    Zwick,     "Hydraulischer    Kalk    und 
Portland-Cement",  pp.  66-67. 


5.  d'Emondeyille,  France.     Vicat,  analyst. 

6.  Lyme  Regis,  England.     Quoted  by  Cummings,  "American  Cements",  p.  35. 

Slaking. — Hydraulic  lime,  after  burning,  is  a  mixture  of  two  distinct 
compounds.  Part  of  the  mass  is  composed  of  lime  silicate,  which  would 
not  slake  if  water  were  poured  on  it,  but  would  form  a  hydraulic  cement 
if  finely  ground.  The  remainder  of  the  hydraulic  lime  consists  simply 
of  quicklime,  which  will  slake  with  water. 

The  result  of  the  mixture  of  the  two  ingredients  is  that  if  water 
be  poured  on  a  lump  of  hydraulic  lime  the  portion  consisting  of  quick- 
lime will  rapidly  take  up  the  water  and  slake.  In  its  slaking  its  expan- 
sion will  break  up  the  entire  mass  into  a  fine  powder.  If  this  operation 
be  done  carefully,  with  just  the  proper  amount  of  water,  the  result  will 
be  a  fine,  dry,  white  powder,  consisting  mostly  of  lime  silicate  with 
about  one  third  to  one  fourth  as  much  of  slaked  lime. 


180  CEMENTS,  LIMES,  AND  PLASTERS. 

In  the  earlier  days  of  hydraulic-lime  manufacture  in  France  (and 
even  at  the  present  day  in  England)  it  was  the  practice  to  put  the 
hydraulic  lime  on  the  market  in  lumps,  just  as  it  is  drawn  from  the 
kiln,  leaving  the  work  of  slaking  it  to  the  purchaser.  At  present,  how- 
ever, the  slaking  in  the  French  works  is  done  at  the  lime-plant.  The 
advantages  of  this  method  of  procedure  are  that  (1)  the  slaking  is  done 
more  uniformly  and  carefully,  so  that  tile  value  and  reputation  of  the 
lime  is  improved,  and  (2)  the  lime  gains  considerably  in  weight  and  bulk 
during  slaking,  so  that  the  cost  of  slaking  is  made  up. 

Slaking  should  be  done  with  as  little  water  as  is '-compatible  with 
thorough  slaking.  The  lime  as  drawn  from  the  kiln  is  therefore  spread 
out  in  thin  layers  and  lightly  sprinkled  with  water.  It  is  then  shoveled 
up  into  heaps  or  into  bins,  where  it  is  allowed  to  remain  for  ten  days 
or  so.  The  slaking  is  completed,  while  the  lime  is  thus  heaped  up,  by 
the  aid  of  the  steam  which  is  generated. 

After  slaking  is  completed,  the  lime  remains  as  a  fine  powder  inter- 
spersed with  lumps  (grappiers)  of  harder  material.  These  lumps  con- 
sist in  part  of  lime  silicate  and  in  part  of  unburned  or  underburned 
limestone.  It  would  be  desirable  if  practicable  to  remove  the  latter 
material,  as  it  is,  of  course,  valueless  as  a  cement.  The  lumps  of  lime 
silicate,  on  the  contrary,  will,  if  finely  ground,  make  a  good  natural 
cement.  This  separation  is,  however,  commercially  impracticable, 
and  therefore  all  the  grappiers  are  treated  together. 

The  lime  after  slaking  is  passed  over  screens  (of  about  50-mesh). 
These  screens  permit  all  the  slaked  lime  to  pass,  but  reject  the  grap- 
piers. The  lime  is  sent  to  the  packers,  while  the  grappiers  are  ground 
finely  under  millstones.  So  far  as  can  be  learned,  a  certain  percentage 
of  ground  grappiers  is  always  added  to  the  lime,  in  order  to  increase 
its  hydraulicity.  As  later  briefly  noted  (p.  185),  the  grappiers  alone 
are  also  sold  as  a  cement. 

The  analyses  by  Durand-Claye,  given  in  Table  75,  are  quoted  in 
Spalding's  "Hydraulic  Cements",  p.  20,  and  serve  to  illustrate  the  com- 
position of  the  various  products. 

In  this  series  analysis  No.  1  is  of  the  lime  which  has  completely 
powdered  during  slaking  and  passed  through  the  first  sieve,  while 
analysis  No.  3  is  of  the  grappiers  rejected  by  this  sieve.  It  will  be 
seen  that  while  the  slaked  lime  has  a  Cementation  Index  of  0.992,  the 
grappiers  are  proportionately  less  rich  in  lime  (CaO),  having  an  index 
of  1.63.  In  order  to  increase  the  hydraulic  properties  of  the  lime  which 
has  passed  the  sieve,  a  certain  proportion  of  ground  grappiers  is  aJdded 
to  it.  This  causes  the  lime  as  marketed  to  have  a  Cementation  Index 


EMINENTLY  HYDRAULIC  LIMES :  GRAPPIER  CEMENTS.         181 


o   g 


g  a  &  s? 
?    I 


182 


CEMENTS,  LIMES,  AND  PLASTERS. 


TABLE  75. 
ANALYSES  OF  KILN  PRODUCTS,  TEIL,  FRANCE. 


1. 

2. 

3. 

4. 

Silica  (SiO2) 

23  05 

23  95 

31  85 

43  90 

Alumina  (A12O3)         .                .... 

Iron  oxide  (i^e2O3)   .  .                 ......... 

j    2.75 

3.10 

4.25 

8.20 

Lime  (CaO)  

65.  ,75 

63  35 

55  60 

45  25 

Magnesia  (MgO)  

1.50 

1   15 

1  20 

0  85 

Water  etc 

6  95 

8  50 

7  10 

2  60 

Cementation  Index 

0  992 

1  08 

1  63 

2  82 

of  1.08,  as  shown  by  analysis  No.  2,  which  is  of  the  Teil  lime  in  its  com- 
mercial form.  During  the  burning  a  small  percentage  of  a  third  compound 
close  in  composition  to  CaO.SiO2  is  formed.  This  product  is  not  used 
in  either  the  hydraulic-lime  or  grappier-cement  industries,  but  is  mixed 
with  slaked  lime  and  used  in  the  manufacture  of  pipe,  tile,  etc.  It  is, 
in  fact,  an  artificial  puzzolana,  as  is  seen  from  its  analysis  (No.  4), 
which  gives  a  Cementation  Index  of  2.82. 

These  analyses  by  Durand-Claye  have  been  used  because  they  form 
a  complete  series.  They  are  not  entirely  representative,  however,  of 
Teil  hydraulic  lime,  as  is  seen  on  comparing  them  with  analyses  No.  2 
and  3  in  Table  76,  below.  These  latter  analyses  give  Cementation 
Indexes  of  0.841  and  0.854  respectively,  which  are  considerably  lower 
than  of  the  corresponding  analyses  of  Table  75. 

TABLE  76. 
ANALYSES  OF  HYDRAULIC  LIMES,  AFTER  SLAKING. 


1. 

2. 

3. 

Silica  (SiO2) 

22  0 

19  05 

18  2 

Alumina  (A12O3)                          .        

2  0 

1  6 

1  2 

Iron  oxide  (Fe2O3)              

2  0 

0  55 

0  8 

Lime  (CaO)         

62.0 

65  10 

60  0 

Magnesia  (MgO)       

1.5 

0  65 

1  32 

Sulphur  trioxide  (SO,) 

0  5 

0  3 

n  d 

Carbon  dioxide  (CO2) 

001 

r  s  00 

Water    

10  0  J 

12.45 

|  n  d 

Cementation  Index  

1  016 

0  841 

o  &r>i 

1 

1.  Typical  hydraulic  lime,  after  slaking.  Le  Chatelier,  Trans.  Am.  Inst.  Min.  Engrs.,  vol.  22, 
p.    16. 

2.  Hydraulic  lime  of  Teil,  after  slaking.  Thorpe,  Diet.  Applied  Chem.,  vol.   1,  p.  474. 

3.  Hydraulic  lime  of  Teil.  after  slaking.  Gillmore,  "Limes,  Cements,  and  Mortars",  p.  125, 

Weight   and   specific   gravity. — Beckwith   states  that   Teil  lime  in 
lumps,   before  slaking,  weighs  36£  Ibs.  per  cubic  foot;    while  slaked 


EMINENTLY  HYDRAULIC  LIMES:  GRAPPIER  CEMENTS.         183 


and  screened  its  weight  averages  about  43  Ibs.  per  cubic  foot.  Accord- 
ing to  Schoch,*  the  hydraulic  limes  average  in  specific  gravity  about 
2.9 

Tensile  and  compressive  strength. — The  results  given  in  Table  77 
are  quoted  by  Schoch  *  as  being  fair  averages  for  hydraulic-lime 
mortars  composed  of  one  part  lime  and  three  parts  sand;  kept  for 
seventy-two  hours  after  molding  in  a  moist  atmosphere  and  the  remain- 
der of  the  time  under  water. 

TABLE  77. 
AVERAGE  STRENGTH  OF  HYDRAULIC  LIMES.     (SCHOCH.) 


Pounds  per  Square  Inch. 

7  Days. 

28  Days. 

1  Year. 

64  Ibs. 
356    " 

100  Ibs. 
683    " 

299  Ibs. 
1920    " 

Compression 

These  results  may  be  compared  with  those  given  in  Tables  78  and  79,. 
which  are  quoted  by  Beckwith  as  the  averages  of  several  series  of  experi- 
ments carried  on  at  Toulon  and  Marseilles  on  hydraulic-lime  mortars- 
composed  of  about  one  part  lime  to  two  parts  of  sand.  These  mortars 
were  made  into  blocks  and  kept  under  salt  water  the  entire  time. 

TABLE  78. 
TENSILE  STRENGTH  OF  TEIL  HYDRAULIC-LIME  MORTAR. 


Time  Immersed. 

Tensil< 

;  Strength 

in  Pounds 

oer  Square 

Inch. 

1. 

2. 

3. 

4. 

5. 

6. 

Average. 

45  days  
90     "    
180     "    

1  year  .  . 

31.71 
85.06 
97.11 
123  43 

40.38 
88.49 
106.22 
111  63 

30.79 
83.78 
89.16 
126.42 

30.83 

77.68 
86.88 
122.15 

'57i59 
86.03 
121.30 

38.42 
83.77 
94.86 
120  .  94 

34.43 
79.39 
93.38 
120  95 

2  years 

141  06 

164  20 

152  63 

Ratio  of  compressive  to  tensile  strength. — When  in  use,  limes  and 
cements  are  usually  subjected  to  direct  compressive  stress  only,  tensile 
strains  being  rarely  applied  in  well-designed  and  well-built  structures. 
In  testing,  however,  a  test  for  tensile  strength  is  much  cheaper  and 
more  readily  applied  than  one  for  compressive  strength.  The  result 
is,  that  though  limes  and  cements  are  almost  entirely  used  in  com- 

*  Schoch,  C.  Die  moderne  Aufbereitung  und  Wertung  der  Mortel-Materialen, 
p.  74. 


184 


CEMENTS,  LIMES,  AND  PLASTERS. 


TABLE  79. 
COMPRESSIVE  STRENGTH  OF  TEIL  HYDRAULIC-LIME  MORTARS. 


Time  Immersed. 

Compressive  Strength  in  Pounds  per  Square  Inch. 

1. 

2. 

3. 

4. 

Average. 

45  days        

219.59 
359.62 
593.98 
612.91 
613.88 

191.75 
362.41 
467.13 
591.84 
577.33 

194.09 
355.20 
451.34 
561.87 
573:92 

205.04 
259.15 
504.24 
588.99 

202.62 
334.10 
504.17 
588.90 
588.38 

90     "       

180     "      

pression,  they  are  usually  tested  in  tension.  For  this  reason  it  is  desir- 
able to  ascertain,  as  definitely  as  possible,  the  ratio  which  exists  between 
the  compressive  and  the  tensile  strength  of  any  type  of  lime  or  cement. 
If  this  ratio  be  once  determined,  a  tensile  test  can  thereafter  be  used  to 
determine  the  compressive  strength  of  the  material. 

In  the  present  case,  the  tensile  and  compressive  tests  given  in 
Tables  77,  78,  and  79  have  been  compared.  The  results  are  sufficiently 
•close  to  indicate  that  the  compressive  strength  of  a  hydraulic-lime 
mortar  mixed  in  the  usual  working  proportions  (1  lime  to  2  or  3  sand) 
will  be  from  five  to  six  times  the  tensile  strength  of  the  same  mixture. 
(The  actual  average  value,  given  by  eight  tests,  for  this  ratio  was  5.38 
to  1.) 

Proportions  for  mortars  and  concretes. — The  following  proportions 
for  making  mortars  and  concretes  with  hydraulic  lime  are  recommended 
by  Beckwith: 

(a)  Mortar  for  use  in  salt  water:  10J  U.  S.  bushels  (590  Ibs.)  of 
Teil  lime  to  1  cubic  yard  of  sand,  equivalent  to  one  scant 
measure  of  lime  to  two  full  measures  of  sand. 
(6)  Mortar  for  use  in  fresh  water:  9  U.  S.  bushels  (506  Ibs.)  of  Teil 
lime  to  1  cubic  yard  of  sand,  equivalent  to  1J  measures  of 
lime  to  3  measures  of  sand. 

(c)  Mortar  for  use  in  air:    7£  U.  S.  bushels  (421  Ibs.)  of  Teil  lime 
to  1  cubic  yard  of  sand,  equivalent  to  1  measure  of  lime  to 
3  measures  of  sand. 
4d)  For  concretes  the  usual  proportions  are: 

(1)  For  use  in  salt  water,  2  measures  mortar  to  3  measures  of 

broken  stone. 

(2)  For  use  in  fresh  water,  1  measure  mortar  to  2  measures  of 

broken  stone. 


EMINENTLY  HYDRAULIC  LIMES:  GRAPPIER  CEMENTS.         185 


Grappier  Cements. 

Grappier  cements  are  made  by  grinding  finely  the  lumps  of  unburned 
and  overburned  material  which  remain  when  a  hydraulic  lime  is  slaked. 
These  lumps,  as  earlier  noted,  consist  partly  of  lime  silicate  and  partly 
of  unburned  limestone.  The  value  of  the  resulting  grappier  cement 
will  depend  on  the  proportions  in  which  these  two  ingredients  occur 
in  the  lumps.  If  lime  silicate  forms  most  of  the  lumps,  the  grappier 
cement  will  be  a  very  satisfactory  material,  approximating  to  Portland 
cement  in  its  properties.  If  most,  or  even  a  large  part,  of  the  lumps 
consist  of  unburned  limestone,  however,  the  grappier  cement  will  be 
practically  worthless. 

Lafarge  cement,  well  known  on  the  American  market  as  a  "non- 
staining"  cement,  is  a  grappier  cement  of  very  satisfactory  composition 
made  at  Teil,  France. 

Composition  of  grappier  cements. 

TABLE  80. 
ANALYSES  OF  GRAPPIER  CEMENTS. 


1. 

2. 

3. 

4. 

5. 

Silica  (SiO2)       

26.5 

31.85 

31.10 

27.38 

24  65 

2.5 

f  4.43 

2.61 

6  55 

1.5 

>4.25 

\2.15 

1  02 

2  60 

Lime  (CaO)     

63.0 

55.60 

58.38 

58.38 

56  30 

1.0 

1.20 

1.09 

0.46 

0  90 

Alkalies  (K  O  Na2O) 

n  d 

n  d 

0  94 

n  d 

n  d 

0.5 

n.  d. 

0.60 

0.43 

0.35 

1     e   n 

f  1.28 

n.  d.  1 

Water  

r  5.0 

7.10 

\n.  d. 

n.  d.  J 

8.65 

Cementation  Index         

1  212 

1  63 

1  560 

1  359 

1  356 

1    Typical  grappier  cement.     Le  Chatelier,  Trans.  Amer.  Inst.  Min,  Engrs.,  vol.  22,  p.  19. 

2.  Teil  grappiers.     Analysis  by  Durand-Claye.     Quoted  by  Spalding,  "  Hydraulic  Cement ",  p.  20. 

3.  Lafarge  cement.     C.  F.  McKenna,  analyst,  1897.     Sales-agents'  circular. 

4.  Lafarge  cement.     Quoted  by  E.  Duryee,  Engineering  News,  vol.  47,  p.  23.     Jan.  9,  1902. 

6.  Malain  grappier  cement.     Quoted  by  Bonnami,  "  Fabrication  et  controle  des  Chaux  Hydrai*. 
liques  ",  p.  54. 

Physical  properties  of  grappier  cements. — The  only  data  available 
on  the  strength,  etc.,  of  grappier  cements  are  those  contained  in  the 
circular  issued  by  the  American  sales-agents  of  the  Lafarge  brand. 
The  tests  were  conducted  in  1897  by  Dr.  C.  F.  McKenna. 

The  Lafarge  cement  gave  the  following  results: 


Specific  gravity,  not  ignited. 

"  "        ignited 

Loss  on  ignition 


2 . 6  Initial  set 4  hours 

2 . 7  Final  set 10  hours 

3 . 83%       Fineness 99 . 8%  through    50-mesh 

"       99. 4%  through  100-    " 


186 


CEMENTS,  LIMES,  AND  PLASTERS. 


TABLE  81. 
TESTS  OP  TENSILE  STRENGTH,  LAFARGE  CEMENT.     (McKENNA.) 


Composition  of  Mortar. 

Tensile  Strength  in  Pounds  per  Square  Inch. 

1 

Week. 

1 
IVJonth. 

3 

Months. 

7 
Months. 

8 
Months. 

1 
Year. 

2 
Years. 

Neat  cement,  22  \%  water.  
Neat  cement,  24%  water 

330 
320 
145 

465 
242 

500 

298 

542 

470 

645 

665 
665 

1  part  cement,  2  parts  sand.  .  .  . 

These  results  have  been  plotted  diagrammatically,   as  shown  in 
Fig.  29. 

TOO 


500 


400 


300 


200 


100 


5  §     §  I 

a   a  £ 

10  i~     co 

FIG.  29.— Tensile  strength  of  Lafarge  (grappier)  cement. 


CHAPTER  XV. 


FEEBLY  HYDRAULIC  LIMES:  SELENITIC  LIMES. 

THE  feebly  hydraulic  limes  have  been  defined  in  Chapter  XIII  as  in- 
cluding those  products  whose  Cementation  Index  ranges  between  0.30 
and  0.70.  This  means  that  in  such  a  product,  no  matter  how  high  the 
burning  temperature,  not  over  70  per  cent  of  its  total  lime  (CaO)  can 
be  in  combination  with  the  silica,  etc.,  while  if  the  Cementation  Index, 
as  shown  by  analysis,  falls  as  low  as  0.30,  only  30  per  cent  of  the  total 
lime  can  be  so  combined,  even  under  the  most  favorable  circumstances. 
As  combination  can  never  be  theoretically  complete,  it  is  safe  to  say 
that  in  the  feebly  hydraulic  limes  only  from  20  to  60  per  cent  of  their 
total  lime  is  combined,  the  remainder  being  left  free  and  capable  of 
slaking.  A  product  containing  so  much  free  lime  and  so  little  in  the 
combined  form  can  obviously  possess  little  hydraulicity  or  strength. 

Limes  of  this  class  would  hardly  merit  description  were  it  not  for 
the  fa"ct  that  they  are  the  usual  type  of  English  hydraulic  limes,  and 
that  they  often  serve  as  a  basis  for  making  a  product — selenitic  lime — 
which  requires  brief  attention. 

TABLE  82. 
ANALYSES  OF  HYDRAULIC-LIME  ROCKS. 


1. 

2. 

3. 

Silica  (SiO  )               

5.00 

4.64 

7.40 

Alumina  (Al  63)       

f  7.08 

2.70 

|    4.23 

10.85 

5.30 

Lime  (CaO)             

48.65 

48.27 

40.82 

Magnesia  (MsrO)                                      

1.86 

4  52 

40.26 

37.92 

37.06 

0.356 

0.443 

0.581 

1.  Holywell,  England.     Muspratt,  analyst. 

2.  Falhagen,  Germany.     Pasch,  analyst. 
3-  Horb,  Wurtemberg.     Knauss,  analyst. 


187 


188 


CEMENTS,  LIMES,  AND  PLASTERS. 

TABLE  83. 
ANALYSES  OF  FEEBLY  HYDRAULIC  LIMES. 


1. 

2. 

3. 

4. 

5. 

Silica  (SiO2)            

7.60 

11.95 

11.00 

16.05 

8.36 

11.60 

4.25 

3.67 

1.92 

I  7  nc 

0.96 

8.52 

3.00 

3.22 

>  7.08 

Lime  (CaO) 

79.09 

65.73 

78.40 

77.29 

81.44 

7.25 

3.93 

1.52 

3.11 

0  439 

0.581 

0.440 

0.621 

0.331 

1.  Falhagen,  Germany.     Pasch,  analyst. 

2.  Horb,  Wlirtemberg.     Knauss,  analyst. 

3.  Fecamp,  France.     Rivot,  analyst. 

4.  Aberthaw,  England.     Quoted  by  Cummings.  "American  Cements",  p.  35. 

5.  Holy  well,  England.     Muspratt,  analyst. 

Tensile  strength. — In  Table  84  are  given  the  results  of  tests,  on  the 
tensile  strength  of  various  English  hydraulic-lime  mortars,  carried 
out  by  Grant  *  about  1880.  These  tests  were  made  on  briquettes  hav- 
ing a  cross-section  of  2J  square  inches ;  but  the  results  given  in  Table  84 
have  been  reduced  so  as  to  give  the  strength  in  pounds  per  square  inch. 


TABLE  84. 
TENSILE  STRENGTH  OF  HYDRAULIC-LIME  MORTARS.     (GRANT.) 


1  Lime: 

3  Sand. 

ILime: 

4  Sand. 

1  Lime  : 

5  Sand. 

1  Lime: 

6  Sand. 

Dry. 

Wat. 

Dry. 

Wet. 

Dry. 

Wet. 

Dry. 

Wet. 

Pounds. 
50 

Pounds. 
68 

Pounds. 
44 

Pounds. 
57 

Pounds. 
30 

Pounds. 
45 

Pounds. 
21 

Pounds* 

28 

48 

95 

49 

59 

32 

47 

23 

27 

Lime  C  

40 

81 

26 

61 

21 

44 

18 

34 

46 

81 

40 

59 

28 

45 

21 

30 

Each  of  the  values  given  in  this  table  represents  the  average  of  the 
results  on  five  specimens  tested.  All  the  tests  were  made  one  year 
after  the  briquettes  were  molded.  The  words  "wet"  and  "dry"  refer 
to  the  fact  that  half  of  the  briquettes  were  kept  in  air  and  the  other 
half  in  water  during  the  entire  year. 


.*  Proc.  Institution  Civil  Engineers,  vol.  62,  p.  165.     1880. 


FEEBLY  HYDRAULIC  LIMES:  SELENITIC  LIMES. 


189- 


The  results  above  tabulated  are  shown  diagrammatically  in  Fig.  30^ 
It  will  be  noted  that  the- "wet"  briquettes  gave  results  exceeding  the 
"dry"  in  an  average  ratio  of  almost  1.6  to  1. 


100  Ibs. 


70 


80  Ibs. 


i 


i 


FIG.  30.— Tensile  strength  of  feebly  hydraulic  limes. 

Compressive  strength. — Tests  on  the  compressive  strength  of  mortars- 
made  *  from  three  English  hydraulic  limes  are  given  in  Table  85.  These- 
tests  were  made  on  6-inch  cubes  kept  in  air  for  one  year  before  testing.. 

*  Proc.  Institution  Civil  Engineers,  vol.  62,  p.  165.     1880. 


190 


CEMENTS,  LIMES,  AND  PLASTERS. 


The  results  have  been  reduced  to  give  the  values  for  compressive  strength 
in  pounds  per  square  inch. 

TABLE  85. 
COMPRESSIVE  STRENGTH  OF  HYDRAULIC-LIME  MORTARS.     (GRANT.) 


Composition 

of  Mortar. 

Kind  of  Lime. 

Lime  A. 

Lime  B. 

Lime  C. 

Average. 

Lime  1,  sand  and 

"     1,     "       " 
«     lf     «       .< 

gravel    6 

Pounds  per 
Square  Inch. 
159 

72 
81 

Pounds  per 
Square  Inch. 

178       » 
172 
179 

Pounds  per 
Square  Inch. 
359 
167 
133 

Pounds  per 
Square  Inch. 
232 
137 
131 

"        8 

"      10 

The  values  given  a,re  the  average  of  ten  specimens  tested. 

Selenitic  Lime:    Scott's  Cement. 

The  cementing  material  known  as  Scott's  cement,  selenitic  cement, 
or  selenitic  lime  consists  essentially  of  lime  (CaO)  plus  a  small  per- 
centage of  sulphur  trioxide  (SOs).  The  lime  used  as  a  basis  for  this 
cement  is  always  a  more  or  less  hydraulic  variety,  while  the  sulphur 
trioxide  may  be  added  to  it  in  the  form  of  either  plaster  of  Paris  or 
sulphuric  acid.  The  resulting  selenitic  lime  or  Scott's  cement  shows  a 
markedly  higher  strength,  both  in  compression  and  tension,  than  the 
lime  from  which  it  was  made. 

Manufacture  of  selenitic  limes. — In  his  earlier  patents  Scott  pro- 
Tided  for  the  manufacture  of  this  product  by  exposing  lime  to  the 
fumes  of  burning  sulphur.  This  was  accomplished  *  "by  reheating 
calcined  lump  lime  in  an  oven  having  a  perforated  floor,  beneath  which 
were  placed  pots  of  burning  sulphur.  The  sulphurous-acid  fumes  from 
the  sulphur  rose  among  the  red-hot  lumps  of  lime,  leading  to  the 
formation  of  calcium  sulphite  (CaSOs),  and  this  in  turn  became  oxidized 
into  calcium  sulphate  (CaSO^.  The  amount  of  sulphurous  acid  thus 
absorbed  by  the  whole  bulk  of  the  lime  was  small,  rarely  exceeding  from 
2  to  3  per  cent,  and  of  course  only  the  exterior  surfaces  of  the  lumps 
became  coated  with  the  sulphur  compound;  but  when  the  cement  was 
ground,  to  prepare  it  for  use,  the  sulphate  of  lime  became  evenly  dis- 
tributed throughout  the  mass. 

In  course  of  time  General  Scott  found  that  he  could  obtain  the  same 
results,  either  by  adding  sulphuric  acid  to  the  water  used  in  preparing 

*  Redgrave,  G.  R.     Calcareous  cements,  p.  176.     1895. 


FEEBLY  HYDRAULIC   LIMES:  SELENITIC  LIMES. 


191 


the  mortar  or  by  the  addition  of  powdered  gypsum  or  plaster  of  Paris 
to  the  ground  lime.  It  mattered  little  in  what  form  the  sulphuric  acid 
was  conveyed  to  the  lime,  and  many  soluble  sulphates  were  found  to 
answer  quite  as  well  as  the  sulphate  of  lime.  Ultimately  Scott  specified 
the  manufacture  of  a  cement,  which  he  named  ' selenitic  cement',  by 
the  addition  of  5  per  cent  of  ground  plaster  of  Paris  to  calcined  hydraulic 
lime,  which  was  then  ground  to  an  impalpable  powder  and  placed  in 
sacks  or  casks  for  use". 

The  hydraulic  lime  used  in  the  manufacture  of  selenitic  lime  is  appar- 
ently always  one  of  the  feebly  hydraulic  varieties  such  as  are  discussed 
earlier  in  the  present  chapter. 

Tensile  strength  of  selenitic  limes. — The  following  table  shows  the 
results  of  tests  *  by  Grant  about  1880  on  various  selenitic  limes.  For 
purposes  of  comparison  tests  are  also  given  on  two  of  the  limes  before 
the  addition  of  sulphate.  The  tests  were  made  on  briquettes  having  a 
sectional  area  of  2J  square  inches ;  but  in  the  table  below  the  results  given 
are  reduced  to  pounds  per  square  inch. 

TABLE  86. 
TENSILE  STRENGTH  OF  SELENITIC  LIMES.     (GRANT.) 


1  Lime: 
3  Sand. 

1  Lime: 
4  Sand. 

1  Lime: 
5  Sand. 

1  Lime: 
6  Sand. 

Dry. 

Wet. 

Dry. 

Wet. 

Dry. 

Wet. 

Dry. 

Wet. 

A.    Gray  lime,  not  selenitic.  .  .  . 

50 
128 
48 
79 
123 
91 
128 

68 
141 
95 
131 
148 
151 
204 

44 
65 
49 
63 
80 
59 
83 

57 
139 
59 
99 
129 
102 
147 

30 
55 

32 

44 
72 
33 
71 

45 
87 
47 
72 
83 
77 
123 

21 

40 
23 
52 

58 
29 

28 
65 
27 
80 
74 
66 
76 

A'.      "        "      selenitic  

B.    Lias  lime,  not  selenitic  

B'      "       "      selenitic 

C.     Selenitic  lime 

D.          "          "      Rugby 

E.          '  «           '  '      Aberthaw  

Each  of  the  above  results  represents  the  average  of  the  tests  of  five 
specimens.  The  tests  were  made  one  year  after  the  briquettes  were 
molded.  The  words  "wet"  and  "dry"  refer  to  the  fact  that  some 
of  the  briquettes  were  kept  in  air  and  others  in  water  during  the  entire 
year.  These  results  as  to  tensile  strength  are  shown  diagrammaticaily 
in  Fig.  31. 


*  Proc.  Institution  Civil  Engineers,  vol.  62,  p.  165.     1880. 


192 


CEMENTS,  LIMES,  AND  PLASTERS. 


Compressive  strength  of  selenitic  limes. — A  number  of  selenitic 
limes  were  tested  for  compressive  strength  by  Grant,  the  results  being 
given  in  Table  87. 


420 


{100 


50 


•  1 


FIG.  31. — Tensile  strength  of  plain  hydraulic  and  selenitic  limes. 

TABLE  87. 
COMPRESSIVE  STRENGTH  OF  SELENITIC  LIMES.     (GRANT.) 


1  Lime: 
6  Sand. 

1  Lime: 
8  Sand. 

1  Lime: 
10  Sand. 

A     Gray  lime  not  selenitic 

159 

72 

81 

A'.      "        "      selenitic             

289 

119 

127 

B.    Lias  lime,  not  selenitic     

178 

172 

179 

B'.     "       "     selenitic  

268 

305 

159 

C.     Selenitic  lime  

414 

239 

210 

D.          "  .        "      Rugby.  . 

577 

533 

329 

E           "           "      Aberthaw 

530 

339 

239 

FEEBLY  HYDRAULIC  LIMES:  SELENITIC  LIMES. 


193 


The  samples  discussed  in  the  above  table  were  made  up  into  6-inch 
cubes  and  kept  in  air  one  year  before  testing.  The  results  in  the  table 
have  been  reduced  to  pounds  per  square  inch. 


300  Ibs. 


200  Ibs. 


100  Ibs. 


1 
I 

FIG.  32. — Compressive  strength  of  plain  hydraulic  and  selenitic  limes. 

The  gain  in  strength  due  to  this  process  of  selenitizing  is  obvious, 
but  it  must  be  recollected  that  it  gives  satisfactory  results  only  when 
employed  on  feebly  hydraulic  limes.  With  common  non-hydraulic 
limes,  and  with  the  better  grades  of  hydraulic  limes,  the  results  are  not 
commensurate  with  the  extra  expense.  For  American  use,  therefore, 
Scott's  process  has  little  to  commend  it,  for  our  good  natural  cements 
would  leave  little  field  for  such  a  product  as  selenitic  lime» 


PART  V.     NATURAL  CEMENTS. 

I* 

CHAPTER  XVI. 
DEFINITION  AND  RELATIONS  OF  NATURAL  CEMENTS. 

BEFORE  taking  up  a  detailed  description  of  the  materials,  man- 
ufacture, and  properties  of  natural  cements  it  will  be  useful  to 
make  some  brief  general  statements  concerning  the  group.  In  the 
present  chapter,  therefore,  an  attempt  will  be  made  to  discuss  the 
natural  cements  as  a  class,  laying  emphasis  upon  the  points  of  resem- 
blance of  the  various  brands  and  disregarding  for  a  time  their  many 
points  of  difference. 

The  difficulties  which  are  encountered  in  such  an  attempt  are  greater 
than  the  reader,  at  first  sight,  may  imagine;  for  few  engineers  realize 
what  a  heterogeneous  collection  of  products  is  included  under  the  well- 
known  name  of  "  natural  cement  ".  The  cause  of  this  lack  of  knowl- 
edge is  not  far  to  seek.  Natural  cements  are  too  low  in  value  to  be 
shipped,  under  ordinary  circumstances,  far  from  their  point  of  pro- 
duction. The  natural  cement  made  at  any  given  locality  has  usually, 
therefore,  a  well-defined  market  area  within  which  it  is  well  known 
and  subject  to  little  competition.  The  engineer  practicing  within 
such  an  area  naturally  forms  his  idea  of  natural  cements  in  general 
from  what  he  knows  of  the  brands  encountered  in  his  work,  and  as  all 
the  brands  from  one  cement-producing  locality  are  apt  to  'resemble 
one  another  quite  closely,  he  is  likely  to  conclude  that  natural  cements 
are  quite  a  homogeneous  class,  with  many  points  of  resemblance  and 
few  of  difference.  The  truth  is,  on  the  contrary,  that  there  may  be 
far  greater  differences  in  strength,  rate  of  set,  chemical  composition, 
etc.,  between  the  natural  cements  made  in  two  different  localities 
than  between  any  given  brand  of  natural  cement  and  a  Portland  cement. 
This  will  be  brought  out  clearly  in  a  later  chapter,  where  the  compo- 

194 


0 100 


UNITED 

SHOWING  LOCATION  OF 
NATURAL  CEMENT  PLANTS 


FIG.  33. 


[To  face  p.  194. 


DEFINITION  AND  RELATIONS  OF  NATURAL  CEMENTS.         195 

sition  and  properties  of  the  various  natural  cements  will  be  discussed 
in  considerable  detail. 

In  the  present  volume  the  term  "  natural  cements  "  will  be  used  to 
include  all  those  cements  which  are  produced  by  burning,  without  pre- 
vious mixing  or  grinding,  a  naturally  impure  limestone  rock,  i.e.,  a 
clayey  or  argillaceous  limestone.  As  so  used  the  term  will  include 
the  class  of  doubtful  products  commonly  known  as  "  natural  Portland 
cements  ",  a  class  which  is  quite  largely  manufactured  in  Belgium 
and  France.  The  reasons  for  including  these  "  natural  Portlands  " 
with  the  natural  cements  instead  of  with  the  true  Portlands  are  stated 
in  detail  in  a  later  section  of  this  volume. 

The  definition  of  natural  cements  giver*  on  a  previous  page  can 
be  restated  here  to  advantage. 

Definition. — Natural  cements  are  produced  by  burning  a  natural 
clayey  limestone  containing  15  to  40  per  cent  of  silica,  alumina,  and 
iron  oxide  without  preliminary  mixing  and  grinding.  This  burning 
takes  place  at  a  temperature  that  is  usually  little,  if  any,  above  that 
of  an  ordinary  lime-kiln.  During  the  burning  the  carbon  dioxide  of 
the  limestone  is  almost  entirely  driven  off,  and  the  lime  combines  with 
the  -silica,  alumina,  and  iron  oxide,  forming  a  mass  containing  silicates, 
aluminates,  and  ferrites  of  lime.  In  case  the  original  limestone  con- 
tained any  magnesium  carbonate  the  burned  rock  will  contain  a  corre- 
sponding amount  of  magnesian  compounds. 

After  burning,  the  burned  mass  will  not  slake  if  water  be  poured 
on  it.  It  is  necessary,  therefore,  to  grind  it  quite  fine,  after  which, 
if  the  resulting  powder  (natural  cement)  be  mixed  with  water,  it  will 
harden  rapidly.  This  hardening,  or  setting,  will  take  place  either  in 
air  or  under  water. 

Relations  of  natural  cements  to  others. — Natural  cements  differ 
from  ordinary  limes  in  two  very  noticeable  ways.  These  are: 

(1)  The  burned  mass  does  not  slake  when  water  is  poured  on  it. 

(2)  After  grinding,  natural-cement  powder    has  hydraulic    proper- 
ties, i.e.,  if  properly  prepared  it  will  set  under  water. 

Natural  cements  are  quite  closely  related  to  both  hydraulic  limes, 
on  the  one  hand,  and  Portland  cement,  on  the  other,  agreeing  with 
both  in  the  possession  of  hydraulic  properties.  They  differ  from 
hydraulic  limes,  however,  in  that  the  burned  natural-cement  rock  will 
not  slake  when  water  is  poured  on  it. 

The  natural  cements  differ  from  Portland  cements  in  the  following 
important  particulars: 

(1)  Natural  cements  are  not  made  by  burning  carefully  prepared 


196  CEMENTS,  LIMES,  AND  PLASTERS. 

and  finely  ground  artificial  mixtures,  but  by  burning  masses  of  natural 
rock. 

(2)  Natural  cements,  after  burning  and  grinding,  are  usually  yellow 
to  brown  in  color  and  light  in  weight,  their  specific  gravity  being  about 
2.7  to  3.10,  while  Portland   cement  is  commonly  blue  to  gray  in  color 
and  heavier,  its  specific  gravity  ranging  from  3.0  to  3.2. 

(3)  Natural   cements   are   always  biuned   at   a  lower  temperature 
than  Portland,  and  commonly  at  a  much  lower  temperature,  the  mass 
of  rock  in  the  kiln  rarely  being  heated  high  enough  to  even  approach 
the  fusing-  or  clinkering-point.  i. 

(4)  In  use  natural  cements  set  more  rapidly  than  Portland  cement, 
but  do  not  attain  such  a  high  ultimate  strength. 

(5)  In  composition,   while   Portland  cement  is  a  definite  product 
whose  percentages  of  lime,  silica,  alumina,  and  iron  oxide  vary  only 
between  narrow  limits,  various  brands  of  natural  cements  will  show  very 
great  differences  in  composition;    while  even  the  same  brand,  analyzed 
at  different  times,  will  show  considerable  differences  in  composition, 
due  to  variations  in  the  natural  limestones  used. 

Cementation  Index. — In  discussing  the  hydraulic  limes  (Chapter 
XIII)  attention  was  called  to  the  desirability  of  devising  some  method  of 
general  applicability  for  comparing  the  hydraulic  activity  of  various 
cementing  materials.  The  defects  of  the  old  "  hydraulic  index "  were 
pointed  out,  and  a  new  and  more  satisfactory  index — the  Cementation 
Index — was  suggested  as  a  substitute.  The  value  of  this  innovation  will 
appear  in  the  present  section,  for  in  dealing  with  the  natural  cements 
such  great  variations  in  composition  are  found  that  it  is  absolutely 
necessary  to  have  some  means  of  comparing  such  different  products. 

The  Cementation  Index  of  any  limestone  or  cement  is  found  by 
applying  the  following  formula: 

(2.8  X percentage  silica)  + 
( 1 .1 X  percentage  alumina)  4- 

Cementation  Index  -,= (. 7 X percentage  iron  oxide) ^^ 

(Percentage  lime) +(1. 4  X  percentage  magnesia) 

When  this  formula  is  applied  to  an  unburned  limestone  it  must  be 
recollected  that  the  percentages  used  in  the  divisor  are  those  of  lime 
(CaO)  and  magnesia  (MgO)  respectively,  not  those  of  lime  carbonate 
(CaCO3)  and  magnesium  carbonate  (MgCO3). 

Example  of  calculation. — The  methods  of  calculating  the  Cementa- 
tion Index  of  any  product  may  be  shown  by  an  example,  the  Utica  natural 
cement  whose  analysis  appears  as  No.  1,  Table  110,  p.  253,  being  selected 


"DEFINITION  AND  RELATIONS  OF  NATURAL  CEMENTS.      197 

for  this  purpose.    The  five  essential  ingredients  of  that  cement,  as  shown 
by  the  analysis,  are: 

Silica  (SiO2) 19.89 

Alumina  (A12O3) 11  -61 

Iron  oxide  (Fe2O3) 1 .35 

Lime  (CaO) 29.51 

Magnesia  (MgO) 20.38 

These  values  are  substituted  in  the  following  formula: 

(2.8  X percentage  silica)  + 
(1.1  X  percentage  alumina)  + 

_  .       T    ,  (. 7 X percentage  iron  oxide) 

Cementation  Index  =-^ —  — ..      .  ,  ..,  .  — r-r 

(Percentage  lime)  +  ( 1 .4  X percentage  magnesia) 

=  (2.8X19.89)  +(1.1X11.61)  +  (.7X1.35) 

(29.51)  +  (1.4X20.38) 
^55.692  +  12.771+0.945 

29.51+28.532 
^69.408 
"  58.042 
=  1.19. 

As  will  be  later  seen,  this  value  is  fairly  characteristic  for  many  natural 
cements. 

Basal  assumptions. — It  has  previously  been  stated  (pp.  170,  171) 
that  the  applicability  of  the  Cementation  Index  depends  upon  the  fact 
that  it  is  the  exact  equivalent  in  percentages  of  a  formula  which  involves 
the  following  assumptions: 

(1)  That  the  hydraulic  activity  of  any  material  depends  on  the 
formation  of  certain  compounds  of  lime  and  magnesia  with  silica,  alumina, 
and  iron  oxide. 

(2)  That  in  a  hydraulic  cement,  lime  combines  with  silica  in  such 
proportions  as  to  form  the  tricalcic  silicate  (  =  3CaO.Si02);    while  it 
combines  with  alumina  in  such  proportions  as  to  form  the  dicalcic 
aluminate  (2CaO.Si02). 

(3)  That  in  a  lightly  burned  natural  cement  at  least  magnesia  may 
be  regarded  as  molecularly  interchangeable  with  lime,  though  of  course 
the  differences  in  their  combining  weights -must  be  allowed  for  when 
the  calculation  is  based  on  percentages. 

(4)  That  iron  oxide  may,  in  similar  fashion,  be  regarded  as  molec- 
ularly interchangeable  with  alumina. 

Of  these  assumptions,  the  third  and  fourth  may  be  questioned  by 
other  investigators,  but  it  will  be  seen  later  that  the  hydraulicity  of 


198  CEMEXT3,  LIMES,  AND  PLASTERS. 

certain  well-known  products  cannot  be  explained  satisfactorily  without 
taking  account  of  the  magnesia  and  iron  oxide  they  contain. 

Use  of  the  Cementation  Index.  —  If  the  assumptions  on  which  the 
Cementation  Index  is  founded  are  well  based,  it  is  evident  that  the 
hydraulic  properties — or,  rather,  the  hydraulic  possibilities — of  a  prod- 
uct are  indicated  by  its  index.  A  product  whose  index  falls  below 
1.00  must  necessarily  contain  free  limtf  or  free  magnesia,  whatever  the 
temperature  at  which  it  is  burned,  and  such  a  product  should  therefore 
be  strictly  classed  with  the  hydraulic  limes,  which  require  slaking  before 
use.  It  will  be  seen  later,  however,  that  if  a  product  Contains  much  mag- 
nesia (say  20  per  cent  MgO  or  over)  its  Cementation  Index  may  fall  below 
1.00  without  demonstrable  defects  in  the  cement.  This  point  is  taken 
up  on  later  pages  in  discussing  the  actual  composition  of  various 
natural  cements.  A  product  with  an  index  exceeding  1.00  can  be  burned 
so  as  to  give  complete  combination  of  all  its  lime  and  magnesia,  leaving 
none  free.  As  the  index  increases,  the  temperature  necessary  to  attain 
such  complete  combination  decreases,  but  the  hydraulic  activity  of  the 
product  also  decreases,  until  an  index  exceeding  2.00  indicates  a  very 
lightly  burned,  but  also  very  feeble,  cement. 

Cementation  Index  of  natural  cements. — The  term  " natural  cement " 
as  used  in  this  volume  will  cover  a  very  large  class  of  cementing  prod- 
ucts. In  the  United  States  the  name  has  become  fairly  well  fixed 
in  use,  so  that  there  need  be  little  misunderstanding  concerning  the 
limits  of  the  groups.  In  English  and  European  practice,  however, 
the  term  "  natural  cement  "  has  never  come  into  extensive  use.  It 
may  therefore  be  necessary  to  state  that,  as  above  defined,  it  includes 
the  lightly  burned  but  often  high-limed  cements  known  to  the  Euro- 
pean trade  as  "  Roman  cements  ",  "  quick-setting  cements  ",  etc.,  as 
well  as  the  so-called  "natural  Portlands  ". 

The  differences  in  composition  between  the  various  cements  included 
in  this  heterogeneous  class  naturally  give  rise  to  corresponding  differ- 
ences in  their  cementation  index.  It  may  be  said  for  the  group  taken 
as  a  whole  that  the  Cementation  Index  of  natural  cements  varies 
between  the  limits  of  1.00  and  2.00,  falling  below  1.00  only  in  the  case 
of  certain  highly  magnesian  cements,  and  that  most  of  the  natural 
cements  will  fall  between  the  narrower  limits  of  about  1.15  to  1.60. 

This  variation  of  the  Cementation  Index  may  be  used  as  a  con- 
venient basis  for  subdividing  the  "natural  cements  "  into  smaller  groups 
of  more  homogeneous  character. 

A.  Cements  with  an  index  between  1.00  and  1.15.  These  products 
when  burned  at  sufficiently  high  temperature  are  rather  slow- 


DEFINITION  AND  RELATIONS  OF  NATURAL  CEMENTS.         199 

setting  and  high  in  tensile  strength,  including  the  "  natural 
Portlands  "  and  allied  products.  If  not  burned  high  enough, 
however,  cements  of  such  low  index  will  necessarily  contain 
large  amounts  of  free  lime  and  magnesia. 

B.  Cements  with  an  index  between  1.15  and  1.60.    These  include 

most  American  natural  cements.  As  the  index  is  higher  than 
in  Class  A,  it  is  not  necessary  to  burn  these  products  at  so 
high  a  temperature.  Practically  all  of  the  European  "Roman" 
cements  will  also  fall  in  this  subgroup. 

C.  Cements  with  an  index  exceeding  1.60.    These  include  the  rela- 

tively low-limed  natural  cements,  which  carry  so  much  clayey 
material  that  only  a  light  burning  is  required  in  order  to  com- 
bine all  their  lime  and  magnesia.  As  the  index  rises  above 
2.00,  the  products  become  feebler  in  hydraulic  properties, 
until  at  about  3.00  they  can  be  considered  only  as  artificial 
pozzuolauas. 


CHAPTER  JXVII. 
RAW  MATERIAL:    NATURAL-CEMENT  ROCK. 

Composition  of  natural-cement  rock. — The  raw  rnaterial  utilized  for 
natural-cement  manufacture  is  invariably  a  clayey  limestone  carrying 
from  13  to  35  per  cent  of  clayey  material,  of  which  10  to  22  per  cent  or 
so  is  silica,  while  alumina  and  iron  oxide  together  may  vary  from  4  to 
16  per  cent.  It  is  the  presence  of  these  clayey  materials  which  give 
the  resulting  cement  its  hydraulic  properties.  Stress  is  often  care- 
lessly or  ignorantly  laid  on  the  fact  that  many  of  our  best-known 
natural  cements  carry  large  percentages  of  magnesia,  but  it  should  at 
this  date  be  realized  that  magnesia  (in  natural  cements  at  least)  may  be 
regarded  as  being  almost  exactly  interchangeable  with  lime,  so  far  as 
the  hydraulic  properties  of  the  product  are  concerned.  The  presence 
-of  magnesium  carbonate  in  a  natural-cement  rock  is  then  merely 
incidental,  while  the  silica,  alumina,  and  iron  oxide  are  essential.  The 
25  per  cent  or  so  of  magnesium  carbonate  which  occurs  in  the  cement 
rock  of  the  Rosendale  district,  New  York,  could  be  replaced  by  an 
equivalent  amount  of  lime  carbonate,  and  the  burnt  stone  would  still 
give  a  hydraulic  product.  If,  however,  the  clayey  portion  (silica, 
alumina,  and  iron  oxide)  of  the  Rosendale  rock  could  be  removed 
leaving  only  the  magnesium  and  lime  carbonates,  the  rock  would  lose 
all  of  its  hydraulic  properties  and  would  yield  on  burning  simply  a 
magnesian  lime. 

This  point  has  been  emphasized  because  many  writers  on  the  sub- 
ject have  either  explicitly  stated  or  implied  that  it  is  the  magnesium 
carbonate  of  the  Rosendale,  Akron,  Louisville,  Utica,  and  Milwaukee 
rocks  that -causes  them  to  yield  a  natural  cement  on  burning.  Even 
a  casual  consideration  of  the  subject  should  have  recalled  to  mind 
the  fact  that  the  Cumberland  and  Lehigh  natural-cement  rocks  are 
practically  free  from  magnesium  carbonate. 

A  limestone  containing  sufficient  argillaceous  matter  to  make  a 
good  natural  cement  can  generally  be  recognized  by  the  characteristic 
-clayey  odor  given  forth  when  breathed  on. 

200 


RAW   MATERIAL:  NATURAL-CEMENT  ROCK.  201 

In  determining  in  advance  of  actual  calcination  whether  or  not 
a  given  rock  will  make  a  good  natural  cement  the  Cementation  Index 
will  prove  of  service.  This  can  be  calculated,  as  explained  on  page  196, 
from  the  analysis  of  the  rock.  If  the  value  of  the  Cementation  Index 
is  over  2.00,  the  rock  will  make  only  a  very  weak  sort  of  cement,  not 
worth  putting  on  the  market  as  a  new  product  in  face  "of  competition 
from  older  and  stronger  brands.  If,  on  the  other  hand,  the  Cementa- 
tion Index  is  less  than  1.00,  the  rock  is  in  most  cases  unavailable,  for 
after  burning  it  will  contain  too  much  free  lime  and  free  magnesia  to 
furnish  a  safe  cement.  As  noted  earlier,  however,  a  rock  whose  index 
falls  between  0.80  and  1.00  can  be  made  into  an  apparently  safe  cement 
if  it  contains  20  per  cent  or  more  of  magnesia,  by  burning  at  a  very  high 
temperature.  If  the  Cementation  Index  falls  between  1.00  and  2.00  it 
<;an  be  assumed  that  a  natural  cement  of  good  quality  can  be  made 
from  the  rock  under  proper  conditions  of  burning,  etc.  Within  these 
limits  the  properties  of  the  cement  will  vary  with  the  index.  A  rock 
with  an  index  of  1.00  to  1.10,  for  example,  will  require  burning  at  high 
temperature,  especially  if  much  lime  be  present  (i.e.,  over  50  per  cent 
CaO).  As  the  index  rises,  the  temperature  necessary  for  burning  de- 
creases. 

American  Natural-cement  Rocks. 

In  the  following  pages  analyses  of  the  rocks  used  at  almost  all  of 
the  natural-cement  plants  of  the  United  States  will  be  given.  Notes 
on  the  physical  character,  geology,  and  other  features  of  these  rocks 
will  also  be  presented. 

Clayey  limestones  of  the  composition  required  for  natural-cement 
manufacture  are  very  'widely  distributed,  both  geologically  and 
geographically,  in  the  United  States.  There  is  hardly  a  State,  in  fact, 
in  which  natural  cement  of  more  or  less  value  has  not  been  made  at 
one  time  or  another.  In  order,  however,  that  a  natural-cement  industry 
can  become  well  established  in  any  given  locality,  certain  things  are 
requisite  in  addition  to-  the  occurrence  of  a  good  natural-cement  rock. 

The  rock  must  not  only  be  of  the  right  composition  to  make  a  good, 
sound,  and  strong  cement,  but  it  must  be  fairly  steady  in  composition, 
and  the  beds  must  be  located  favorably  for  cheap  extraction  of  the 
rock,  either  by  quarrying  or  by  mining.  Fuel  must  also  be  obtainable 
at  reasonable  rates.  A  good  local  market  and  cheap  transportation 
to  outside  points  are  necessities. 

Of  the  many  localities  in  the  United  States  at  which  deposits  of 
good  natural-cement  rock  occur,  so  few  possess  the  commercial  advan- 


202  CEMENTS,  LIMES,  AND  PLASTERS. 

tages  mentioned  above  that  the  important  natural-cement-producing 
districts  are  correspondingly  few.  According  to  the  United  States 
Geological  Survey  Report  for  1903  there  were  65  natural-cement  plants 
then  in  operation.  Of  these  20  were  in  New  York  State,  15  in  the 
Louisville  district  of  Indiana  and  Kentucky,  7  in  the  Lehigh  district 
of  Pennsylvania,  4  in  Maryland,  3  in  the  Utica  district  of  Illinois,  2  each 
in  Georgia,  Kansas,  Minnesota,  Ohio^  Texas,  Virginia,  and  Wisconsin, 
and  1  each  in  North  Dakota  and  West  Virginia.  This  suffices  to  show 
the  extent  to  which  the  American  natural-cement  industry  has  become 
concentrated  in  certain  favorable  localities.  ^ 

Georgia. — Two  natural-cement  plants  are  located  in  northwest 
Georgia,  but  they  use  cement  rocks  from  two  different  geological  forma- 
tions, and  their  raw  materials  and  products  differ  widely  in  composition. 

The  plant  of  the  Chickamauga  Cement  Company  is  located  at  Ross- 
ville,  Ga.,  a  few  miles  south  of  Chattanooga.  The  raw  material  used 
is  a  thin-bedded  slaty  limestone  of  Chickamauga  (Ordovician)  age, 
which  is  'here  exposed  over  a  considerable  area.  In  geologic  age,  as 
well  as  in  chemical  composition,  this  rock  is  quite  similar  to  the  cement 
rock  of  the  Lehigh  district  of  Pennsylvania,  but  the  Georgia  deposit 
is  not  so  thick  as  in  that  region.  These  shaly  limestones  outcrop  at 
many  points  in  northwest  Georgia  and  northern  Alabama,  but  so  far 
have  been  utilized  for  natural  cement  only  at  the  Rossville  plant. 

The  second  plant,  that  of  the  Howard  Hydraulic  Cement  Company, 
is  working  on  limestones  of  quite  different  character. 

The  Conasauga  formation  of  the  Cambrian  is  described  by  Dr.  C.  W. 
Hayes  as  being  "  normally  composed — at  the  base  of  thin  limestones 
interbedded  with  shales,  then  of  yellowish  or  greenish  clay  shales,  and 
at  the  top  of  calcareous  shales,  grading  into  blue  seamy  limestones". 

The  Western  and  Atlantic  Railroad,  now  operated  under  lease  by 
the  Nashville,  Chattanooga  and  St.  Louis  System,  crosses  the  outcrop 
of  these  rocks  from  above  Adairsville  to  within  a  mile  of  Kingston. 
At  one  point  near  the  southern  end  of  this  belt  limestone  obtained 
from  beds  lying  near  the  top  of  the  Conasauga -formation  has  long  been 
utilized  in  the  manufacture  of  natural  cement  at  the  plant  of  the  Howard 
Hydraulic  Cement  Company,  at  Cement,  Bartow  County,  Ga.,  about 
two  miles  north  of  Kingston. 

In  the  low  ridge  east  of  the  railroad  at  Cement  station  a  section  of 
these  Conasauga  limestones  has  been  measured  by  Spencer.* 


*  The  Paleozoic  group  of  Georgia,  p.  100. 


RAW  MATERIAL:  NATURAL-CEMENT  ROCK.  203 

The  series  shown,  from  the  top  down,  was  as  follows: 

Feet. 
"Blue  limestone 8 

Slaty  limestone  (cement  rock) 4 

Blue  limestone 6 

*  Argillaceous  limestone 2 

*  Siliceous  limestone  (hydraulic) 4 

*  Siliceous  limestone  (cement  rock) 7 

Fine  black  limestone 12 

Earthy  limestone 3 

Shales 

When  the  plant  was  visited  by  the  writer,  in  the  fall  of  1902,  the 
three  beds  marked  with  asterisks  (*)  were  being  worked  for  natural 
cement.  Spencer  quotes  the  following  analyses,  made  by  W.  J.  Land: 

(1)  (2) 

Silica  (SiO2) 22. 10         10.00 

Alumina  (A12O3) 5.45  6.10 

Iron  oxide  (Fe2O3) 1 .80  2.00 

Lime  (CaO) 24.36  30.80 

Magnesia  (MgO) 12.38  12.42 

Carbon  dioxide  (CO2).. 32.76  37.88 

Organic  matter 0.15  0 . 50 

•      Water 1.00  0.30 

Cementation  Index 1 . 69          0 . 749 

Of  these  analyses,  No.  1  probably  represents  the  composition  of 
the  7-foot  bed  of  cement  rock  noted  in  Spencer's  section,  while  No.  2 
is  probably  from  the  4-foot  bed  of  hydraulic  limestone  immediately 
overlying  this.  As  these  beds  are  both  worked  for  cement,  the  index 
of  the  product  lies  between  those  of  the  two  rocks. 

Illinois. — Three  natural-cement  plants  operated  by  two  companies 
are  now  working  in  Illinois,  all  of  them  being  located  near  Utica,  La 
Salle  County.  The  rock  used  is  a  limestone  belonging  to  the  so-called 
"  Lower  Magnesian  "  group  of  early  Western  geologists.  It  is  of 
Ordovician  age  and  underlies  the  St.  Peter's  sandstone. 

The  section  exposed  in  the  neighborhood  of  the  Utica  cement-plants 
is  as  follows  from  the  top  downward: 

Thickness. 
Cement  rock 7  feet 

Limestone 16-22    " 

Cement  rock 6    " 

Sandstone 2-4    " 

Cement  rock 5    " 

• 

Of  the  three  cement-rock  beds  shown  in  this  section,  the  upper- 
most bed  gives  a  very  quick-setting  cement,  while  the  two  lower  beds 
furnish  products  of  much  slower  set. 


204 


CEMENTS,  LIMES,  AND  PLASTERS. 


TABLE  88. 
ANALYSES  OF  NATURAL-CEMENT  ROCK,  UTICA,  ILLINOIS. 


1. 

2. 

3. 

4. 

5. 

Silica  (SiO2)            

12.22 

17.01 

1 

f  14.15 

Alumina  (A12O3)     i  . 

9.39 

3.35 

>  21.00 

21.12 

1    6.37 

Iron  oxide  (Fe2O3)  .  . 

3.90' 

2.39 

2.00 

1.12 

2.35 

Lime  (CaO)                                  .    . 

24  40 

32  85 

24  36 

23.66 

26  32 

Magnesia  (MgO)             

10  43 

8  45 

14.31 

15.22 

12.10 

Alkalies  (K2O,Na2O)    

n.  d. 

n  d 

0.18 

n.  d. 

0.18* 

Sulphur  trioxide  (SO3)  

n.  d. 

1.81 

n.  d. 

n.  d. 

1.81 

/  34.00 

35.35 

34.70 

Water  

}  38  .  48 

34.12 

1    3.00 

1.07 

2.03 

Cementation  Index 

1  21 

1  19 

1.11 

*  Far  too  low:    true  value  is  probably  over  4  per  cent. 

1.  F.  W.  Clarke,  analyst.     Sample  collected  by  E.  C.  Eckel. 

2.  C.  Richardson,  analyst.     Brickbuilder,  vol.  6,  p.   151.     July,  1897. 

3.  Blaney  &  Mariner,  analysts.     "Geology  of  Illinois",  vol.   1,  p.  151. 

4.  Blaney,  analyst.     Trans.  Am.  Inst.  Min.  Engrs.,  vol.  13,  p.  180. 

5.  Average  of  preceding  four  analyses. 

Indiana-Kentucky. — The  plants  of  the  "  Louisville  district  "  are 
mostly  located  in  Indiana,  though  one  or  two  mills  are  in  operation 
on  the  Kentucky  side  of  the  Ohio  River.  The  rock  is  a  fine-grained 
clayey  limestone  of  Devonian  age.  In  color  it  varies  from  light  drab  to 
dark  or  bluish  drab  when  fresh,  weathering  to  a  dull  buff  on  long  ex- 
posure. The  cement-bed  varies  from  10  to  16  feet  in  thickness  in  the 
different  quarries.  As  shown  by  the  calculated  values  of  the  Cementa- 
tion Index,  the  rock  varies  greatly  in  composition. 

TABLE  89. 
ANALYSES  OP  NATURAL-CEMENT  ROCK,  LOUISVILLE  DISTRICT,  IND.-KY. 


1. 

2. 

3. 

4. 

5. 

6. 

Silica  (SiO2)              .    .  . 

9  69 

9  80 

13  65 

15  21 

18  33 

13  36 

Alumina  (A1^O3)     

2  77 

2  03 

3  46 

4  07 

4  98 

3  46 

Iron  oxide  (Fe2O3)   

1.95 

1.40 

1.45 

1  44 

1  67 

1  58 

Lime  (CaO)     

29.09 

29.40 

34.55 

33  99 

30  41 

31  49 

Magnesia  (MgO) 

15  69 

16  70 

7  97 

7  57 

8  04 

11  19 

Carbon  dioxide  (CO2).  .  . 
Cementation  Index  

40.14 
0.618 

41.49 

35.92 

35.03 

32.76 
1  39 

37.07 

Analyses  1-5  inclusive  were  made  by  W.  A.  Noyes.      Quoted   by  Siebenthal,  25th  Ann.  Rep. 
Indiana  Dept.  Geology  and  Natural  Resources,  pp.  380-386. 

1.  Rock  used  for  "Crown"  brand,  Hausdale  mill,  New  Albany  Cement  Company. 

2.  "Fern  Leaf"  brand,  Ohio  yalley  mill,  Ohio  Valley  Cement  Company. 

3.  "Diamond"  brand,  Falls  City  mill,  Union  Cement  and  Lime  Co. 

4.  "Star  "  -brand,  Speed  mill,  Louisville  Cement  Company. 

5.  '*  'Black  Diamond",  Black  Diamond  mill,  Union  Cement  and  Lime  Co. 


RAW  MATERIAL:  NATURAL-CEMENT  ROCK. 


205. 


Kansas. — The  natural-cement  district  of  Kansas  is  located  around 
Fort  Scott,  where  a  44-foot  bed  of  natural-cement  rock  outcrops.  The 
rock  is  a  dark-colored,  fine-grained,  compact  limestone  of  Carboniferous 
age.  It  extends  for  a  considerable  distance  throughout  the  State,  but 
as  yet  has  been  worked  for  natural  cement  only  in  the  immediate  vicinity 
of  Fort  Scott. 

TABLE  90. 
ANALYSES  OF  NATURAL-CEMENT  ROCK,  FORT  SCOTT,  KANSAS. 


1. 

2. 

3. 

4. 

Silica  (SiO?)   

15  21 

17  26 

21  80 

18  09 

4.56 

2  05 

3  70 

3  44 

Iron  oxide  (Fe  Oo) 

n  d 

5  45 

3  10 

4  27 

36.52 

34.45 

35.00 

35  32 

Masjnesia  (MffO)           

5  07 

5  28 

3  50 

4  62 

Carbon  dioxide  (CO2)   

34  27 

32  87 

33  00 

33  38 

Cementation  Index  

1  68 

1.  Smith,  Mineral   Industry,  vol.    1,  p.   49. 

2.  Brown,   "Cement   Directory",  2d  ed.,  p.  276. 

3.  Richardson,  Brickbuilder,  vol.  6,  p.  151.     July,  1897. 

4.  Average  of  preceding  analyses. 

Maryland. — The  natural-cement  industry  of  Maryland  has  been 
carried  on  in  three  separate  areas.  One  of  these  areas — including  the 
old  plants  at  Antietam  and  Shepherdstown — will  be  described  later 
under  the  heading  of  West  Virginia-Maryland.  The  other  two  areas 
include  respectively  the  plants  at  Cumberland  and  Potomac  in  Alle- 
gany  County,  and  that  at  Round  Top  or  Hancock  in  Washington 
County.  In  both  of  these  areas  the  limestones  used  are  of  the  same 
geologic  age,  and  approximately  of  the  same  composition,  so  that  they 
will  here  be  described  together.  Analyses  are  given  in  Table  90. 

In  geologic  age  the  natural-cement  rock  of  the  Cumberland-Han- 
cock district  corresponds  closely  to  that  used  in  the  various  New  York 
districts,  being  assigned  by  geologists  to  the  Salina  group  of  the  Silurian. 
It  is  a  shaly  limestone,  varying  in  color  from  dark  bluish  gray  to  dull 
black.  In  the  Cumberland  area  it  is  exposed  in  four  beds  of  sufficient 
thickness  to  be  worked,  these  cement-beds  being  separated  by  shales 
and  limestones.  The  separate  beds  vary  from  6  to  17  feet  in  thickness. 

Minnesota. — Two  natural-cement  plants  are  in  operation  in  Minnesota. 
One  of  them  is  located  at  Mankato,  Blue  Earth  County,  and  uses  a 
limestone  of  the  Lower  Magnesian  (Ordovician)  series.  The  analyses 
(Table  91)  of  the  raw  material  used  at  this  plant  have  been  published. 


206 


CEMENTS,  LIMES,  AND  PLASTERS. 


TABLE  91. 
ANALYSES  OP  NATURAL-CEMENT  ROCKS,  CUMBERLAND  AND  HANCOCK,  MARYLAND. 


1. 

2. 

3. 

4. 

5. 

Silica  (SiO2)  

19.81 

24.74 

] 

f  28.72 

22.07 

7.35 

16.74 

>  27.1 

\12.28 

12.12 

Iron  oxide  (Fc2Oo)     ....... 

2  -.41 

6^0 

1.5 

5.22 

3.36 

Lime  (CaO)             

35.76 

23141 

36.40 

25.54 

30.28 

2.18 

4.09 

2.52 

1.10 

2.47 

Alkalies  (Na2O,K2O)    

n.  d. 

6.18 

0.3 

n.  d. 

* 

n.  d. 

2.22 

n.  d. 

1.53 

* 

Carbon  dioxide  (CO2)  

/22.90 

31.38 

Water  

i  31  .  74 

\    n.  d. 

n.  d. 

>  24  .  40 

27.60 

Cementation  Index  

1  68 

3.15 

1.62 

3.60 

2.29 

*  Data  insufficient  for  averaging. 

1.  Hancock,  Md.     C.   Richardson,  analyst.     Brickbuilder,  vol.   6,  p.   151.   .July,   1897. 

2.  Cumberland,    Md.     E.    C.    Boynton,    analyst.     Quoted    by   Gillmore,    "Limes,   Cements,   and 

Mortars",   p.    125. 

3.  Hancock,   Md.     C.   Huse,   analyst.     Quoted  by   Gillmore,   "Limes,   Cements,   and  Mortars", 

p.   125. 

4.  Cumberland,  Md.     C.  Richardson,  analyst.     Brickbuilder,  vol.  6,  p.  151.     July,  1897. 

5.  Average  of  preceding  four  analyses. 

TABLE  92. 
ANALYSES  OF  NATURAL-CEMENT  ROCK,  MANKATO,  MINN. 


1. 

2. 

3. 

4. 

5. 

6. 

Silica  (SiO?)  

16.00 

12.14 

10.10 

16.80 

8.90 

11.80 

Alumina  (A12O3)     

5  85 

4  62 

2  78 

8.76 

3  30 

3  46 

Iron  oxide  (Fe2O3)  

2  73 

1.84 

1.34 

tr. 

1  02 

tr. 

Lime  (CaO)  

22.40 

22.66 

25.96 

22.20 

24  85 

24.64 

Magnesia  (MgO)  

14.99 

16.84 

14.91 

11.99 

18.49 

16.61 

Alkalies  (K2O  Na2O)      .  .    . 

0  76 

3  52 

3  50 

4  75 

1  53 

2  59 

Sulphur  trioxide  (SO3)  

n  d 

0  13 

0  26 

0  22 

0  18 

0  22 

Carbon  dioxide  (CO2)  

34  11 

39  07 

41  29 

35  90 

41  80 

40  85 

Cementation  Index  

1  22 

0  88 

0  69 

1  45 

0  58 

0  77 

1.  C.   F.   Sidener,  analyst,      llth  Ann.  Rept.   Minn.   Geol.   Surv.,  p.   179. 
2-6.  Clifford  Richardson,  analyst.     Cement  Directory,  p.  206. 

The  second  plant  is  said  to  be  located  at  Austin,  Mower  Co.    If  this 
location  be  correct,  the  limestone  used  is  probably  of  Devonian 

ANALYSIS  OF  NATURAL-CEMENT  ROCK,  AUSTIN,  MINN. 

Silica  (Si02).... l 

Alumina  (A12O3) J      D'^ 

Iron  oxide  (Fe2O3) 2 . 09 

Lime  (CaO) 27.55 

Magnesia  (MgO) 13 .80 

Sulphur  trioxide  (SO3) 0 .06 

Carbon  dioxide  (CO2) .  36.84 


RAW  MATERIAL:  NATURAL-CEMENT  ROCK. 


207 


New  York. — In  the  State  of  New  York  natural  cement  is  now  manu- 
factured in  four  distinct  localities.  These  are  in  order  of  importance: 
(1)  the  Rosendale  district  in  Ulster  County,  (2)  the  Akron-Buffalo  dis- 
trict in  Erie  County,  (3)  the  Fayetteville-Manlius  district,  mostly  in 
Onondaga  County,  and  (4)  at  Howe's  Cave  in  Schoharie  County. 

The  clayey  limestones  used  in  these  four  districts  occur  in  three 
different  but  closely  related  geological  formations,  all  in  the  Upper 
Silurian  group.  The  sequence  and  relation  of  these  formations,  from 
the  top  downwards,  is  shown  in  the  following  table. 


Formation. 

Ulster  County. 

Schoharie 
County. 

Onondaga 
County. 

Erie  County. 

Manlius  limestone 
(cement  rock). 

' 

Worked  for 
cement  at 
Manlius,  etc. 

Absent. 

Rondout  limestone 
(cement  rock). 

Upper  cement- 
bed    of    the 
Rosendale 
district. 

Worked      for 
cement      at 
Howe's 
Cave. 

Absent. 

Cobleskill  limestone 
(not  used  for  ce- 
ment). 

Bertie  limestone 
(cement  rock). 

Lower  cement- 
bed    of    the 
Rosendale 
district. 

Present  in  On- 
o  n  d  a  g  a 
County  but 
rarely    used 
for  cement. 

Worked  for 
cement  at 
Akron  and 
Buffalo. 

For  convenience  these  districts  will  be  described  not  in  the  order 
of  their  relative  importance  but  in  geographic  order,  from  east  to  west. 

The  Rosendale  district  lies  entirely  in  Ulster  County,  the  principal 
cement-rock  quarries  being  located  at  East  Kingston,  Rondout,  Rosen- 
dale,  Binnewater,  Lawrenceville,  and  High  Falls.  Two  distinct  beds 
are  worked  at  most  of  these  points,  differing  in  chemical  composition 
as  well  as  in  geological  age.  Darton  states  *  that  at  Rosendale  the 
lower  bed,  or  dark  cement  rock,  averages  about  21  feet  in  thickness, 
and  the  upper,  or  light  cement  rock,  about  11  feet,  the  two  cement- 
beds  being  here  separated  by  14  or  15  feet  of  worthless  limestone.  The 
lower  bed  lies  directly  on  the  Clinton  quartzite,  the  even  upper  surface 

*  13th  Ann.  Rept.  N.  Y.  State  Geologist,  vol.  1,  1894,  p.  334. 


208 


CEMENTS,  LIMES,  AND  PLASTERS. 


of  which  affords  an  admirable  floor  for  the  galleries.  For  about  18 
inches  at  the  bottom  the  dark  cement  rock  is  too  sandy  for  use.  With 
this  exception  and  a  few  small  layers  of  chert  it  is  all  available.  At 
Whiteport  the  upper  bed  is  12  feet  thick  and  the  lower  18  feet,  while 
they  are  separated  by  17  to  20  feet  of  limestone. 

.    TABLE  9.3. 

f» 

ANALYSES  OF  NATURAL-CEMENT  Rock,  ROSENDALE  DISTRICT,  N.  Y. 


1. 

2. 

3. 

4. 

5. 

6. 

7. 

8. 

18.52 
6.34 
2.63 
25.31 
12.13 
n.  d. 
0.90 
33.31 
n.  d. 

1.43 

Silica  (SiO2) 

10.90 
3.40 
2.28 
29.57 
14.04 
n.  d. 
0.61 
37.90 
n.  d. 

15.37 
9.13 
2.25 
25.50 
12.35 
n.  d. 
n.  d. 
34.20 
1.20 

18.11 
4.64 
3.00 
24.30 
14.26 
n.  d. 
tr. 
34.01 
n.  d. 

18.76 
8.34 
1.85 
25.96 
11.07 
n.  d. 
1.35 
32.00 
n.  d. 

21.32 
7.39 
1.71 
23.75 
11.07 
n.  d. 
1.90 
30.74 
n.  d. 

'"21.41 
}  10.  09  I 

25.80 
10.09 
n.  d. 
0.66 

J30.93J 

23.80 
4.17 
4.71 
22.27 
12.09 
n.  d. 
0.90 
31.00 
n.  d. 

Alumina  (A12O3)       

Iron  oxide  (Fe2O3)     

Lime  (CaO)       

Magnesia  (MgO) 

Alkalies  (K2O,Na.,O)  
Sulphur  trioxide  (SO3)        .  ~ 

Carbon  dioxide  (CO2)  

Water    

Cementation  Index 

1.  Lawrenceville.     J.  O.  Hargrove,  analyst.     Letter  to  writer,  Oct.  4,  1900. 

2.  Rondout.     L.  C.  Beck,  analyst.     "Mineralogy  of  N.  Y.",  p.  78. 

3.  Lawrenceville.     J.  O.  Hargrove,  analyst.     Letter  to  writer,  Oct.  4,  1900. 

6.  "  Rosendale  district.     C.  Richardson,    analyst.      Brickbuilder,    vol.    6,  p.   151. 
July,  1897. 

7.  Lawrenceville.     J    O.  Hargrove,  analyst.     Letter  to  writer,  Oct.  4,  1900. 

8.  Average  of  preceding  seven  analyses. 

Northward  and  northwestward  from  the  Rosendale-Rondout  dis- 
trict no  natural-cement  plants  are  to  be  found  until  Schoharie  County 
is  reached.  Here,  at  Howe's  Cave,  a  single  plant  has  long  been  engaged 
in  the  manufacture  of  cement  from  a  7-foot  bed  of  rock. 

TABLE  94. 
ANALYSES  OF  NATURAL-CEMENT  ROCK,  SCHOHARIE  COUNTY,  N.  Y. 


1. 

2. 

3. 

Silica  (SiO2)     .-,  

12  89 

9  92 

1 

Alumina  (A12O3)                              .                .    . 

}    -,         -.r    f 

n   d 

>  11.50 

Iron  oxide  (Fe2O3)           

J11.15J 

n   d 

1  50 

Lime  (CaO)       

30  90 

38  26 

31  75 

Magnesia  (MgO)     .  .  .  .  0  «  

9  38 

9  00 

14.91 

Carbon  dioxide  (CO2)  

34.60 

39.96 

40.34 

Cementation  Index.  

1  07 

1.  Bottom  of  cement-bed,  Howe's  Cave. 

Geologist,  p.  69. 

2.  Top  of  cement-bed,  Howe's  Cave.      C.  O.  Schaeffer,  analyst. 

69. 


C.  O.  Schaeffer,  analyst.     18th  Ann.  Rept.  N.  Y.  State 
18th  Ann.  Rept.  N.  Y.  State 


Geologist,  p. 
3.  Howe's  Cave.     L.  C.  Beck,  analyst.     "Mineralogy  of  New  York",  p.  79. 


RAW  MATERIAL:  NATURAL-CEMENT  ROCK. 


209 


The  cement  industry  in  central  New  York  is  at  present  practically 
confined  to  Onondaga  County,  though  as  a  matter  of  historical  interest 
it  may  be  noted  that  the  first  natural  cement  made  in  the  United  States 
was  manufactured  in  1818  in  Madison  County. 

The  natural-cement  rock  of  this  central  district  occurs  in  two  beds 
which  are  usually  separated  by  1  to  4  feet  of  blue  limestone.  The 
upper  cement-bed  is  a  little  over  4  feet  thick  at  the  eastern  border  of 
Onondaga  County,  becoming  thinner  to  the  westward  until  it  pinches 
out  entirely  in  the  the  Split  Rock  quarries,  but  reappearing  again  at 
Marcellus  Falls,  where  it  is  almost  3  feet  thick  and  showing  a  thick- 
ness of  slightly  over  4  feet  at  Skaneateles  Falls.  At  this  last  point 
it  is  separated  from  the  lower  cement-bed  only  by  a  shaly  parting  a 
few  inches  thick,  so  that  the  two  are  worked  together  as  practically 
one  bed  9J  feet  thick.  The  lower  bed  is  less  variable  in  thickness, 
ranging  from  4  to  a  trifle  over  5  feet. 

The  entire  cement  series  is  overlaid  by  purer  limestones,  but  the 
cement-rock  quarries  are  usually  located  at  points  where  these  over- 
lying limestones  are  thin  and  can  be  readily  stripped. 


TABLE  95. 

ANALYSES  OF  NATURAL-CEMENT  ROCK,  CENTRAL  NEW  YORK. 


1. 

2. 

3. 

4. 

5. 

6. 

Silica  (SiO2)  

10  97 

10  95 

\ 

f  8  95 

11  76 

10  66 

Alumina  (A10O3)  

4.46 

5.32 

>  13.50 

\4.90 

2  73 

4  35 

Iron  oxide  (Fe2O3)  

1.54 

1.30 

1.25 

1.75 

1.50 

1  47 

Lime  (CaO) 

27  51 

30  92 

25  24 

27  35 

25  00 

27  20 

Magnesia  (MgO) 

16  90 

13  64 

18  80 

16  70 

17  83 

16  77 

Carbon  dioxide  (CO2) 

37  94 

38  31 

39  80 

38  65 

39  33 

38  81 

Water  

n.  d. 

n.  d. 

1.41 

1.70 

1  50 

1  53 

Cementation  Index  

0.71 

1.  Upper  cement-bed,  E.  B.  Alvord  quarry,  Jamesville,  Onondaga  County.     Bull.  44  N.  Y.  State 

Mus.,  p.  806. 

2.  Lower  cement- bed,  E.  B.  Alvord, quarry ,  Jamesville,  Onondaga  County.     Bull.  44  N.  Y.  State 

Mus.,  p.  806. 

3.  One  and  one  half  miles  west  of  Manlius,  Onondaga  County.     L.  C.  Beck,  analyst.     "Mineralogy 

of  New  York",  p.  81. 

4.  One  and   one  half  miles   southwest  of  Chittenango,  Madison   County.     L.  C.   Beck,  analyst. 

"Mineralogy  of  New  York",  p.  80. 

5.  Chittenango,  Madison  County.     Seybert,  analyst.     Trans.  Am.  Philos.  Soc.,  vol.  2,  n.  a.,  p.  229. 

6.  Average  of  preceding  five  analyses. 

In  Erie  County  natural-cement  plants  have  long  been  established 
at  Akron  and  Buffalo.  The  bed  of  cement  rock  used  varies  in  thick- 
ness from  5  to  8  feet.  "  It  is  a  firm,  fine-grained  compact  rock  of  a 
blue-gray  color,  weathering  to  a  yellowish  white.  The  Buffalo  plant 


210 


CEMENTS,  LIMES,  AND  PLASTERS. 


works  its  cement  rock  by  quarrying  methods,  stripping  off  the  over-, 
lying  limestones;  but  the  plants  at  Akron  all  obtain  their  raw  mate> 
rial  by  mining. 

TABLE  96. 
ANALYSES  OF  NATURAL-CEMENT  ROCKS,  AKRON-BUFFALO  DISTRICT,  NEW  YORK. 


y  . 

f*  l. 

2. 

3. 

4. 

Silica  (SiO2)  

9  03 

10  68 

33  80* 

9  85 

Alumina/  (  Al2Oo) 

2  25 

\      .    .,  f 

3  96 

3  10 

Iron  oxide  (Fe2O3) 

0  85 

}    4-61»i 

0  88 

0  87 

Lime  (CaO)     ....          

26  84 

25  65 

19  93 

26  25 

Magnesia  (MgO)       

18  37 

17  93 

9  17 

18  15 

Alkalies  (K2O,Na2O)  

0  85 

n  d 

n   d 

Sulphur  trioxide  (SO3)  

n  d 

n  d 

0  50 

Carbon  dioxide  (CO2)  

40  33 

Water      

0  98 

}  25  .  90 

Cementation  Index  

0  610 

*  Called  "silica,  clay,  and  insoluble  silicates". 

1.  G.  Steiger,  analyst.     Bulletin  168,  U.  S.  Geol.  Survey. 

2.  Lathbury  and  Spackman,  analysts. 

3.  E.   Boynton,   analyst.     Gillmore,  "Limes,  Cements,  and  Mortars",  p.   125. 

4.  Average  of  analyses  1  and  2. 

I  am  informed  by  Mr.  Uriah  Cummings,  of  the  Cummings  Cement  Co., 
Akron,  N.  Y.,  that  none  of  the  analyses  given  in  Table  96  are  really  repre- 
sentative of  the  Akron  natural-cement  rock.  The  analyses  are  presented, 
therefore,  subject  to  this  criticism. 

North  Dakota. — The  single  natural-cement  plant  operating  in  this 
state  is  located  about  ten  miles  east  of  Milton,  Cavalier  County.  The 
rock  used  is  a  soft,  chalky  limestone  of  Cretaceous  age  and  outcrops 
in  a  bluff  several  hundred  feet  high.  At  present,  however,  only  a 
10-foot  bed  is  being  worked,  by  mining.  (See  Table  97.) 

Ohio. — Small  natural-cement  plants  have  been  established  at  vari- 
ous points  in  Ohio,  those  at  Defiance  and  New  Lisbon  being  worthy 
of  some  notice.  The  Defiance  plant  used  a  black  calcareous  shale 
of  Devonian  age.  If  published  analyses  be  Correct  (see  Nos.  1  and  2 
in  Table  98)  this  rock  is  by  far  the  most  argillaceous  material  used 
anywhere  for  this  purpose. 

Pennsylvania. — A  fairly  large  production  of  natural  cement  has 
always  been  maintained  in  the  Lehigh  district  of  eastern  Pennsylvania, 
though  at  present  natural-cement  manufacture  there  is  merely  inci- 
dental to  the  great  Portland-cement  industry  of  the  district. 

The  analyses  given  in  Table  99  purport  to  be  representative  of  the 
rock  used  at  various  Lehigh  district  natural-cement  plants.  It  is  hardly 


RAW  MATERIAL:  NATURAL-CEMENT  ROCK. 


211 


TABLE  97. 
ANALYSES  OF  NATURAL-CEMENT  ROCK,  NORTH  DAKOTA. 


l. 

2. 

3. 

4. 

5. 

Silica  (SiO2)       

14  00 

16  60 

13  10 

16  20 

16  54 

Alumina  (A12O3)  

Iron  oxide  (Fe2O3)  

>    6.70 

7.10 

7.60 

7.56 

8.20 

Lime  (CaO) 

37  60 

35  50 

37  80 

35  10 

35  20 

Sulphur  trioxide  (SO3)  

0.58 

0.60 

n.  d. 

n.  d 

n.  d. 

Sulphur  (S) 

1  45 

1  38 

n  d 

n  d 

n  d 

Cementation  Index  

1  24 

6. 

7. 

8. 

9. 

10. 

Silica  (SiO2) 

14  90 

15  24 

19.20 

17  36 

16  00 

Alumina  (A12O3)           

Iron  oxide  (Fe2O3)        

\    8.28 

7.26 

8.90 

8.78 

7.50 

Lime  (CaO)     

36.90 

36.70 

32.60 

34.90 

35.60 

Sulphur  trioxide  (SO3)  

n.  d. 

0.40 

n.  d. 

n.  d. 

0.67 

Sulphur  (S) 

n  d 

1  99 

n  d 

n  d 

1  61 

Cementation  Index   

1.92 

TABLE  98. 
ANALYSES  OF  NATURAL-CEMENT  ROCKS,  OHIO. 


1. 

2. 

3. 

4. 

5. 

Silica  (SiO2)           

39.95 

42.0 

16.41 

30.60 

15  65 

Alumina  (A12O3)  

I  20  .  22  < 

7.0 

5.44 

6.8 

Iron  oxide  (Fe9Oq) 

7  1 

3  38 

\  13.00  | 

2  5 

Lime  (CaO) 

10  06 

9  91 

26  05 

22  74 

38  64 

Magnesia  (MgO)                   .  .  . 

2  92 

5.81 

12  55 

7  23 

1  62 

Carbon  dioxide  (CO2)  
Water  and  organic       

124.03J 

14.18 
14.0  . 

34.32 
n.  d. 

25.81 
n.  d. 

32.14 
n.  d. 

Cementation  Index 

1  25 

1.  Defiance.     J.  E.  Whitfield,  analyst.     Bull.  U.  S.  Geol.  Survey  No.  55,  p.  80. 

2.  Defiance.     R.   C.   Kedzie,  analyst.     Cement  Directory. 

3.  Bellaire.     N.  W.  Lord,  analyst.     Repts.  Ohio  Geol.  Surv.,  vol.  6,  p.  673. 

4.  Warnock.     Wormley,  analyst.     Rept.  Ohio  Geol.  Surv.,  1870,  p.  451. 

5.  New  Lisbon.     N.  W.  Lord,  analyst.     Rept.  Ohio  Geol.  Surv.,  vol.  6,  p.  673. 

necessary  to  say  that  Nos.  1  and  3  are  absolutely  unfit  for  such  use. 
No.  2,  on  the  other  hand,  is  quite  satisfactory.  I  regret  that  these 
very  untrustworthy  analyses  are,  at  present,  the  only  ones  available. 
Texas. — The  second  analysis  on  p.  212  has  been  published  *  as  repre- 
senting the  average  of  the  material  used  in  making  natural  cement  by  a 

*  22d  Ann.  Rept.  U.  S.  Geol.  Survey,  pt.  3,  p.  737. 


212 


CEMENTS,  LIMES,  AND   PLASTERS. 


TABLE  99. 
ANALYSES  OF  NATURAL-CEMENT  ROCK,  LEHIGH  DISTRICT,  PA. 


1. 

2. 

3. 

4. 

Silica  (SiO2) 

11  62 

18  34 

27  77 

19  24 

Alumina  (A12O3)     

Iron  oxide  (F  e2O3)  ^  

j    6.25 

7.49 

14.29 

9.34 

Lime  (CaO)  '.  :'.  

44  20 

37  60 

29  94 

37  25 

Magnesia  (MgO) 

•  1  27 

1  38 

1  55 

1  40 

Carbon  dioxide  (CO2) 

36  11 

31  06  \ 

Wd,ter    

n  d 

3  94  J 

26.30 

32.47 

Cementation  Index  

0  843 

1  49*- 

2  87 

1.  Siegfried,  Pa.     Mineral  Industry,  vol.  1,  p.  49. 

2.  Coplay,  Pa.     Mineral  Industry,  vol.  1,  p.  49. 

3.  Lehigh  district.     Quoted  by  C.  Richardson.     Brickbuilder,  vol.  6,  p.  151.     July,  1897. 

4.  Average  of  preceding  three  analyses. 

Texas  natural-cement  plant.  It  is  obvious  that,  if  this  statement  be 
correct,  the  product  obtained  by  burning  a  rock  of  such  composition 
cannot  be  a  natural  cement  in  any  proper  use  of  the  term.  It  would, 
in  fact,  be  merely  a  very  weak  hydraulic  lime. 


5.77 

2  M 


ANALYSIS  OF  NATURAL-CEMENT  ROCK,  TEXAS. 
Silica  (Si02)  ..................................... 

Alumina  (A12O3)  ................................. 

Iron  oxide  (Fe2(X)  ........................  '  ....... 

Lime  (CaO)  .....  .-  ................................   50.45 

Magnesia  (MgO)  .................................     0  .28 

Virginia.  —  For  many  years  natural  cement  has  been  burned  near 
Balcony  Falls,  Rockbridge  County,  Va.  The  rock  used  is  a  clayey 
magnesian  limestone  of  Cambrian  age,  closely  related  geologically  and 
technologically  to  that  described  below  as  being  used  in  West  Virginia. 

TABLE  100. 
ANALYSES  OF  NATURAL-CEMENT  ROCK,  VIRGINIA. 


1. 

2. 

3. 

Silica  (SiO2)                   

17  38 

17  21 

17  30 

Alumina  (A12O3)          

tr 

6  18 

Iron  oxide  (Fe2O3)          

}      7-80    { 

1  62 

1  62 

Lime  (CaO)                 

34  23 

24  85 

29  54 

Magnesia  (MgO)           

9  51 

16  58 

13  05 

Carbon  dioxide  (CO2)   

30.40 

37  95 

34  17 

Cementation  Index  

1  18 

1.  Balcony  Falls.     E.  C.  Boynton,  analyst.     Gillmore,  "Limes,  Cements,  and  Mortars",  p.  125 

2.  Balcony  Falls.     C.  L.  Allen,  analyst.     "The  Virginias",  vol.  3,  p.  88. 

3.  Average  of  preceding  two  analyses. 


RAW  MATERIAL:  NATURAL-CEMENT  ROCK. 


213 


West  Virginia-Maryland.  —  A  wide  belt  of  magnesian  limestones  of 
Cambrian  age  crosses  Maryland  into  the  eastern  part  of  West  Virginia. 
Several  small  natural-cement  plants  have  been  established  in  this  district 
at  various  times,  particularly  near  Antietam,  Md.,  and  Shepherdstown, 
W.  Ya. 


ANALYSIS  OF  NATURAL-CEMENT  ROCK,  ANTIETAM 


Silica  (Si02) 

Alumina  (A12O3) 

Iron  oxide  (Fe2O3).  . . . 

Lime  (CaO) 

Magnesia  (MgO) 

Alkalies  (K2O,Na2O).  . 
Sulphur  trioxide  (SO3). 
Carbon  dioxide  (CO2). . 
Water.  . 


MD. 
(i) 
15.97 


23.  72 
15.6 

n.  d. 

0.71 

34  82 


Cementation  Incfex 1 . 14 

(1).  Antietam,  Md.     C.  Richardson,  analyst.     Brickbuilder,  vol.  6,  p.  151. 

Wisconsin. — Two  plants  in  Wisconsin  are  engaged  in  the  manufacture 
of  natural  cement  from  a  clayey  magnesian  limestone  of  Devonian  age. 
These  plants  are  located  north  of  Milwaukee,  near  the  lake.  The  cement- 
rock  deposit  is  very  thick,  compared  to  most  natural-cement  proposi- 
tions, a  quarry  face  22  feet  high  being  worked  by  the  Milwaukee  Cement 
Company. 

TABLE  101. 
ANALYSES  OP  NATURAL-CEMENT  ROCKS,  MILWAUKEE  DISTRICT,  Wis. 


1. 

2. 

3. 

4. 

5. 

Silica  (SiO  ) 

17  00 

17  56 

17  56 

16  99 

17  28 

Alumina  (A12O.>) 

4  25 

1  41 

1  40 

5  00 

3  02 

Iron  oxide  (Fe2O3)  

1.25 

3.03 

2.24 

1.79 

2.21 

Lime  (CaO)             

24.Q.4 

25.50 

27  14 

23.15 

25.11 

Magnesia  (MgO)           

11.90 

15  45 

13  89 

16.60 

14.46 

Carbon  dioxide  (CO2)  

32.46 

37.05 

36.45 

36.47 

n.  d. 

1.18 

1.  Mineral  Industry,  vol.  6,  p.  95. 

2.  Trans.  Am.  Inst.  Min.  Engrs.,  vol.  8,  p.  507. 

3.  "         "       "         "          "          "    ••   *«    •• 

4.  "         »       "         "          "          "    "   "    " 

5.  Average  of  preceding  four  analyses. 


214  CEMENTS,  LIMES,  AND  PLASTERS. 

European  Natural-cement  Rocks. 

As  noted  later,  the  European  natural-cement  industry  dates  back 
to  1796,  in  which  year  the  manufacture  of  natural  cement  was  com- 
menced simultaneously  in  France  and  England.  At  present  the  indus- 
try is  established  in  practically  everv^  country  of  Europe,  though  it 
is  of  course  subject  to  severe  competition  from  Portland  cement  on 
the  one  hand  and  the  better  class  of  hydraulic  limes  on  the  other.  Euro- 
pean natural  cements  form  two  fairly  distinct  classes,  which  are  there 
called  respectively  "natural  Portlands  "  and  "  Roman  cements  ": 

(1)  The  natural  Portlands,  which  are  described  on  pages  215-217  in 
detail,  are  natural  cements  of  low  cementation  index  (1.05  to  1.15  usu- 
ally), low  in  magnesia,   and  burned  at  fairly  high  temperatures.     In 
consequence  of  the  combination  of  their  low  index  and  relatively  high 
burning,   these  products  approach  true  Portland  cements  in  analysis 
and   physical   properties,    though    they   necessarily   vary   considerably 
from  time  to  time  according  to  the  rock  from  which  they  are  made. 
The  best  of  these  products  will  pass  low-grade  Portland  tests,  and  were 
formerly  largely  exported  to  this  country,  where  they  were  unloaded 
on  the  architects  and  engineers  who  specified  "  foreign  Portland  cement  ". 
The  poorer  "  natural   Portlands  "   are   often   adulterated  with  slag  or 
unburned  limestone,   in  order  to  make  their  bulk  composition  agree 
on  analysis  with  that  of  true  Portlands. 

While  the  "  natural  Portlands  "  are  often  useful  products,  there 
seems  to  be  no  reason  for  classing  them  with  the  true  Portlands,  for 
the  term  Portland  is  now  understood  to  imply  that  a  very  careful  and 
finely  ground  artificial  mixture  has  been  made  before  burning. 

(2)  The  Roman  cements  form  the  second  class  of  European  natural 
cements.     They  are  usually   cements  of  moderately  high  index   (1.20 
to  1.60),  and  are  also  usually  but  not  invariably  low  in  magnesia.     They 
correspond  therefore  quite  closely,  so.  far  as  index  is  concerned,  to  the 
best  of  the  American  natural  cements.     In  American  practice,  how- 
ever, low-magnesia  natural  cements  are  quite  rare,  as  can  be  seen  by 
referring  to  the  tables  of  analyses  on  pages  253  to  260,  while  in  Europe 
high-magnesia  cements  are  very  scarce. 

It  may  be  of  interest  to  call  attention  here  to  the  fact  that  Quick- 
setting  artificial  cements  of  high  index  (1.20  to  1.60),  and  very  lightly 
burned,  have  been  made  at  several  points  in  Europe.  These  products 
would  correspond  in  every  way  with  our  natural  cements,  except  in  that 
they  are  made  from  artificial  mixtures  and  are  therefore  more  expensive 


RAW  MATERIAL:  NATURAL-CEMENT  ROCK.  215 

to  make.  Wherever  a  good  natural-cement  rock  is  obtainable,  therefore, 
these  "artificial-natural"  cements  are  driven  out  of  the  market. 

Natural-cement  materials  of  Belgium.  — "  Natural  Portland  ". 
cement,  as  well  as  Roman  cement,  is  extensively  manufactured  in  cer- 
tain parts  of  Belgium. 

The  following  analysis  is  representative  of  the  composition  of  the 
rock  from  which  these  "  natural  Portlands  "  are  made: 

Silica  (SiO2) 15.75 

Alumina  (A12O3) 3.95 

Iron  oxide  (Fe2O3) 1 .00 

Lime  (CaO) 43. 10 

Magnesia  (MgO) . . .       0.49 

Sulphur  trioxide  (SO3) 0 . 50 

Carbon  dioxide  (CO2) 1  __ 

Water /  d< 

Cementation  Index 1 . 12 

It  will  be  seen  that  if  rock  of  the  composition  represented  by  the 
above  analysis  could  be  steadily  obtained  it  would  certainly  be  an 
excellent  natural  mixture  for  a  Portland  cement.  In  composition  it 
is  admirable,  while  its  index  is  about  that  of  the  average  commercial 
Portland.  In  practice,  however,  the  variations  in  composition  of  the 
rocks  from  various  parts  of  the  quarry  are  sufficient  to  prevent  the 
product  from  being  sufficiently  uniform  to  be  considered  a  Portland 
cement  in  our  modern  use  of  that  term.  This  will  be  seen  on  referring 
to  the  analyses  of  these  Belgian  products  given  on  page  261. 

A  report*  on  the  Belgian  cement  industry  states: 

"The  most  important  center  for  the  manufacture  of  natural  and 
artificial  Portland  cement  in  Belgium  is  the  calcareous  district  of  Tournai, 
in  the  consular  district  of  Brussels.  Some  of  the  quarries  in  this  district 
date  back  several  centuries,  when  they  were  principally  worked  for 
building  stone  and  for  the  manufacture  of  hydraulic  lime.  The  cal- 
careous stone  of  these  quarries,  which  originated  the  now  extensive 
and  important  industry  of  cement-manufacture,  extends  for  many 
miles  in  length  in  apparently  inexhaustible  quantity.  Ordinary  lime, 
best  hydraulic  lime,  slow-setting  cement  (Portland),  and  quick-setting 
cement  (Roman)  are  especial  products  of  these  immense  quarries. 

"  Natural  Portland  cement  is  obtained  from  calcareous  stone,  which 
is  carefully  analyzed  and  dosed,  calcined  in  coke-heated  kilns,  and,  after 
burning,  finely  pulverized.  Before  burning,  the  stone  presents  a  fine, 

*  Roosevelt,  R.  W.     Manufacture  of  Portland  cement  in  Belgium, 


216  CEMENTS,  LIMES,  AND  PLASTERS. 

close  grain  and  is  of  a  peculiar  pasty  appearance.  Prior  to  calcina- 
tion the  stone  is  carefully  analyzed,  to  ascertain  the  exact  quantity 
of  lime,  as  well  as  other  chemical  properties,  it  may  contain.  The 
stone  loses  about  one  third  of  its  weight  during  the  process  of  burning, 
which  also  changes  it  to  a  brown  tinge.  When  withdrawn  from  the 
kiln  the  cement  is  put  under  sherds  to  thoroughly  cool  before  being 
ground.  After  grinding  arid  before  Hbeing  barreled  it  is  put  into  pits 
.and  left  undisturbed  for  two  months. 

"  Natural  Portland  cement  was  first  manufactured  in  Belgium  in 
1882«  The  following  are  the  principal  works  now  engaged  in  this  enter- 
prise: Compagnie  Generate  des  Ciments  Portland  de  1'Escaut,  Dumon 
et  Cie,  and  Goblet,  Delward  et  Cie,  Tournai;  Societe  Anonyme  de  Chercg, 
Chercg;  L'  Union  Fraternelle,  La  Franco-Beige,  and  Dutoit  &  Tell  freres, 
Calonne;  Lemain  &  Fleury,  Lampe  et  Cie,  and  Societe  Anonyme  du  Can- 
aan, Antoing;  Vve  Alex.  Dapsens  and  Duquesne  et  Cie,  Vaulx;  Laurent 
Delvigne  &  fils,  Gaurany;  the  United  Ghent- Antwerp  Portland  Cement 
Works,  Ghent.  With  few  exceptions,  these  establishments  have  formed 
a  syndicate,  under  the  name  of  '  Mutualite  Commerciale  des  Ciments 
Beiges',  with  headquarters  at  Tournai.  The  society  sells  about 
1,200,000  barrels  of  cement  annually.  The  syndicate  has  adopted 
as  a  trade-mark  the  figure  of  a  hammer.  Any  firm,  however,  of  the 
syndicate  having  a  trade-mark  is  privileged  to  use  it.  For  instance, 
those  firms  having  the  well-known  '  rhinoceros  ',  '  trowel ',  l  sword  ', 
etc.,  use  them  in  conjunction  with  the  syndicate  trade-mark.  Inde- 
pendently of  the  trade-marks  of  the  manufacturers,  important  buyers 
of  the  Mutualite  who  have  labels  enjoying  a  certain  reputation  are 
permitted  to  affix  them  on  the  barrels.  It  is  stated  that  the  principal 
object  of  this  arrangement  by  the  Belgian  manufacturers  is  to  warn 
and  protect  purchasers  against  persons  who  purchase  Roman  cement 
for  export  without  mark  or  label  and  unknown  and  unauthorized  by 
the  manufacturers  have  Portland- cement  labels  affixed  to  the  barrels 
at  port  of  shipment.  The  Mutualite  has  sent  circulars  to  interested 
parties  in  the  United  States  informing  them  of  the  measures  adopted 
to  prevent  this  fraud.  Hereafter  all  barrels  containing  cement  manu- 
factured, shipped,  or  sold  by  this  syndicate  will  be  fire-marked  as  fol- 
lows: First  quality,  inside  and  outside  of  barrel,  'Portland  Warranted 
M.  C.  B.';  second  quality,  inside  only,  '  Deuxieme  quality';  third 
quality,  inside  only,  '  Ciment  Romain  '. 

"  Roman  cement  is  also  manufactured  in  the  Tournai  district.  It 
is  much  cheaper  than  Portland  cement,  the  selling  price  being  about 
50  per  cent  less  than  the  Portland.  It  is  much  employed  in  Belgium, 


RAW  MATERIAL:  NATURAL-CEMENT  ROCK. 


217 


replacing,  advantageously,  a  good  hydraulic  lime.  Manufacturers, 
however,  will  not  guarantee  it,  as  it  is  made  of  refuse  stone  not  suit- 
able for  the  manufacture  of  Portland  cement.  It  has  a  natural  light- 
yellow  color.  Cinders  are  very  often  added,  changing  it  to  a  grayish 
<jolor  resembling  Portland  cement,  and  also  increasing  its  resistance  in 
a  slight  degree.  This  is  the  product  which  is  purchased  by  unscrupu- 
lous exporters  and  sold  by  them  marked  as  Portland  cement.  This 
fact  is  significant  and  should  attract  the  attention  of  builders,  to  avoid 
disasters  such  as  the  unexpected  collapse  of  buildings,  where  first-class 
cement  has  been  supposed  to  have  been  employed  ". 

Fig.  34  shows  the  results  of  a  series  of  tests  of  American  Portlands, 
American  natural  cements,  and  Belgian  "natural  Portlands".  These 
results  may  be  accepted  as  quite  representative  of  the  various  types  of 
•cements  tested,  and  show  clearly  that  the  so-called  "natural  Portlands" 
have  little  in  common  with  true  or  artificial  Portlands. 

Natural-cement  materials  of  England. — The  materials  used  by 
Parker,  the  first  manufacturer  of  English  natural  cements,  were  septaria 
— i.e.,  nodules  of  clayey  lime  carbonate.  These  occur  in  certain  forma- 
tions in  the  south  of  England,  and  are  still  used  in  the  English  natural- 
cement  industry.  The  supply  is  obtained  along  the  coasts,  where  the 
nodules  have  been  washed  out  of  the  beds  which  contain  them. 

TABLE  102 
ANALYSE  OF  NATURAL-CEMENT  ROCKS,  ENGLAND. 


1. 

2. 

3. 

4. 

5. 

Silica  (SiO2) 

]           r 

18  0 

17  20 

)( 

21    Qft 

Alumina  (A12O3) 

h  32  00  j 

6  6 

6  8 

33  00  \ 

3  50 

Iron  oxide  (Fe2O3) 

3  7 

12  8 

8  20 

Lime  (CaO)   

35  28 

39  64 

29  34 

33  88 

32  37 

Magnesia  (MgO)     

2  00 

0  10 

3  33 

2  71 

2  71 

Alkalies  (K2O,Na2O)  

0  80 

n  d 

1  00 

0  80 

1  10 

•Carbon  dioxide  

29  92 

29  46 

26  73 

29  61 

28  42 

Water  

n  d 

1  30 

2  80 

n  d 

1  80 

1.  Sheppey  septaria.  Redgrave,  "Calcareous  Cements",  p.  49. 

2.  Sheppey  septaria.  Berthier,  analyst.     Burnell,  "Limes,  Cements,  Mortars,  etc.",  p.  80. 

3.  Sheppey  septaria.  Knauss,  analyst.     Zwick,  "Hydraulischer   Kalk  und  Portland-Cemente", 

p.  69. 

4.  Harwich  seotaria.  Redgrave,  "Calcareous  Cements",  p.  49. 

5.  Harwich  septaria.  Knauss,  analyst.     Zwick,  "Hydraulischer  Kalk  und  Portland-Cemente", 

p.  69 


218 


CEMENTS,  LIMES,  AND  PLASTERS. 


Age  of  briquettes 
FIG.  34  —Tensile  strength  of  various  classes  of  cement.      (Philadelphia  tests,  1897.) 


RAW  MATERIAL:  NATURAL-CEMENT  ROCK. 


219 


Excavation  of  the  Rock.* 

In  excavating  a  natural-cement  rock  the  preferable  method  of  working, 
so  far  as  cheapness  is  concerned,  is  quarrying.  But  so  many  of  the 
natural-cement  beds  now  worked  are  thin  (from  4  to  8  feet  in  total 
thickness)  or  occur  in  such  steeply  inclined  positions,  that  a  surprisingly 
large  percentage  of  the  raw  material  is  obtained  by  mining.  In  the 
Rosendale  district  of  New  York,  for  example,  mining  is  the  common 
mode  of  extracting  the  rock;  and  the  same  is  true  of  the  plants  in  the 


**  *r   * 


FIG.  35. — Loading  cars,  Speed  quarry,  Speeds,  Ind. 

Akron  district,  New  York,  of  those  in  Maryland,  North  Dakota,  Illinois 
and  Kansas,  of  the  Howard  plant  in  Georgia,  and  of  many  of  the  Louis- 
ville district  plants.  The  plants  of  the  Milwaukee  district,  the  Rossville 


*  Further  details  concerning  quarrying  costs    and  methods  will  be  found  on 
pages  367-381. 


220 


CEMENTS,  LIMES,  AND  PLASTERS. 


plant  in  Georgia,  a  number  of  those  in  the  Louisville  district,  and  several 
others  work  open  quarries. 

This  difference  in  general  practice,  taken  in  connection  with  differ- 
ences in  labor  costs,  etc.,  causes  a  wide  variation  between  different 
plants  in  the  total  cost  of  raw  material  delivered  at  the  kilns. 

Open  quarries  can  be  readily  worked  at  costs  of  from  20  to  35  cents 
per  ton  of  rock.  In  most  cases  the  Question  of  handling  stripping 
economically  is  more  important  than  the  costs  of  actual  quarrying. 
At  one  of  the  Louisville  district  plants,  where  hoists  are  used  in  the 
quarry  (Fig.  35)  for  loading  the  cars,  the  stripping  is  removed  by  scrapers 
whose  power  is  derived  from  these  hoists. 

In  an  area  such  as  the  Rosendale  district,  where  practically  all  the 
cement  rock  is  won  by  mining,  costs  will  naturally  be  higher  than  where 
open  quarries  are  operated.  At  one  of  the  largest  mills  the  rock  can 
be  delivered  on  top  of  the  kilns  for  a  trifle  under  50  cents  per  ton.  I 
am  informed  that  at  another  large  mill,  rock  was  mined  for  a  series  of 
years  at  a  cost  of  about  35  cents  per  ton. 


FIG.  36. — Crusher  for  raw  rock  at  Speed  mill,  Speeds,  Ind. 

Summing  up  these  considerations,  it  is  probably  within  safe  limits 
to  say  that  the  cost  per  ton  of  rock  may  vary  from  about  20  cents  in 
a  well-managed  quarry  to  perhaps  60  cents  or  even  more  in  a  mine. 


RAW  MATERIAL:  NATURAL-CEMENT  ROCK.  221 

As  the  rock  wil)  lose  from  25  to  40  per  cent  of  weight  during  the  process 
of  burning  (averaging  about  33  J  per  cent),  the  cost  per  ton  of  burned 
rock  will  vary  from  30  to  90  cents.  Reducing  this  to  terms  of  barrels 
of  cement,  the  cost  of  raw  material  per  barrel  of  finished  cement  may 
range  from  4  to  13  cents. 

After  the  raw  material  has  been  excavated,  no  preliminary  treat- 
ment is  strictly  necessary  before  sending  it  to  the  kilns.  It  is  advisable, 
however,  to  feed  the  kilns  with  lumps  of  approximately  equal  size, 
because  if  the  charge  consists  of  a  mixture  of  large  and  small  masses 
of  rock  the  latter  will  be  overburned  before  the  former  are  properly 
calcined.  In  most  plants  this  rough  sizing  is  accomplished  by  sledging, 
the  larger  pieces  at  the  quarry.  A  few  plants,  however,  use  crushers, 
one  installation  being  illustrated  in  Fig.  36. 

References  on  natural-cement  rock. — The  natural-cement  rocks  of 
the  various  states  are  described  more  fully  in  the  reports  and  papers- 
listed  below.  For  convenience  these  have  been  arranged  by  States  in 
alphabetical  order. 

UNITED  STATES  in  general.  Eckel,  E.  C.  Cement  materials  and  cement 
industry  of  the  United  States.  Bulletin  243,  U.  S.  Geolog- 
ical Survey.  1905. 

Gillmore,  Q.  A.     Limes,  Cements,  and  Mortars. 
Richardson    C.     Limes,  hydraulic  cement,  mortar,  and  con- 
crete.    Brickbuilder,  vol.  6,  pp.  151-153,  175-179,  202-204, 
228-229.     1897. 

CALIFORNIA.  Grimsley,  G.  P.  The  Portland-cement  industry  in  California. 
Engineering  and  Mining  Journal,  July  20,  1901. 

CONNECTICUT.  Lowrey,  T.  Water  cement  of  Southington,  Conn.  Amer. 
Journal  of  Science,  vol.  13,  pp.  382-383.  1828. 

FLORIDA.  Cummings,  U.     Natural-cement  rock  in  Florida.     20th  Ann. 

Rep.  U.  S.  Geol. 'Survey,  pt.  6,  pp.  549-550.     1899. 

GEORGIA.  Cummings,  U.     Natural-cement  rock  at  Rossville,  Ga.     21st 

Ann.  Rep.  U.  S.  Geol.  Survey,  pt.  6,  pp.  410-411.     1901. 
Spencer,    J.  W.     The    Paleozoic    group  of    Georgia.     Report 
Georgia  Geol.  Survey. 

ILLINOIS.  Freeman,  H.  C.     The  hydraulic-cement  works  of  the  Utica 

Cement  Co.,  La  Salle,  111.     Trans.  Amer.  Institute  Mining; 
Engrs.,  vol.  13,  pp.  172-181.     1885. 

INDIANA-KENTUCKY.  Siebenthal,  C.  E.  The  Silver  Creek  hydraulic  limestone 
of  southeastern  Indiana.  25th  Ann.  Rep.  Indiana  Dept. 
Geology,  pp.  331-389.  1901. 

KANSAS.  Haworth,  E.     Hydraulic  cement  in  Kansas.     Mineral  Resources- 

of  Kansas  for  1897,  pp.  66-69.     1898. 


222 


CEMENTS,  LIMES,  AND  PLASTERS. 


MARYLAND.  O'Harra,  C.  C.  Cement  industry  in  Allegany  County.  Report 
on  Allegany  County,  Maryland.  Geol.  Survey,  pp.  185- 
186.  1900. 

MINNESOTA.  Upham,  C.  Report  on  Blue  Earth  County.  Final  Reports 
Minn.  Geol.  Survey,  vol.  1,  pp.  415-437. 

NEW  YORK.        Bishop,  I.  P.    The  structural  and  economic  geology  of  Erie 
County,  N.  Y.      15th  Ann.  Rep.  New  York  State  Geolo- 
gist, vol.  1,  "pp.' 305-382.     1897. 
Geddes,    G.    Survey   of    Onondaga   County,    N.    Y.    Trans. 

N.  Y.  Agric.  Soc.  for  1859,  pp.  219-352.     1859. 
Luther,  D.  D.     The  economic  geology  ofc  Onondaga  County, 
N.  Y.     15th  Ann.  Rep.  New  York  State  Geologist,  vol.  1, 
pp.  241-303.     1897. 

Pohlman,  J.  Cement  rock  and  gypsum  deposits  in  Buffalo. 
Trans,  Amer.  Inst.  Mining  Engrs.,  vol.  17,  pp.  250-253. 
1889. 

Hies,  H.  Lime  and  cement  industries  of  New  York.  Bulletin 
44  N.  Y.  State  Museum,  pp.  640-848.  1903. 

OHIO.  Bleininger,  A.  V.     Manufacture  of  hydraulic  cements.     Bul- 

letin 3,  Ohio  Geol.  Survey,  1904. 

Lord,  N.  W.  Natural  and  artificial  cements  of  Ohio.  Reports 
Ohio  Geological  Survey,  vol.  6,  pp.  671-695.  1888. 

VIRGINIA.  Anon.     James     River     Cement     Company,    Va.      Engineer 

(London),  Sept.  29,  1899. 

WASHINGTON.  Armstrong,  L.  K.  Portland  and  natural  cements  of  the 
Pacific  Northwest.  Mining,  vol.  9,  pp.  134-141.  1-902. 


CHAPTER  XVIII. 
MANUFACTURE  OF  NATURAL  CEMENTS. 

THE  manufacture  of  natural  cement  is,  compared  to  that  of  Portland 
cement,  a  very  simple  proposition  from  a  mechanical  point  of  view. 
Only  two  general  processes  are  involved — burning  and  grinding.  In 
the  present  chapter  these  processes  will  be  taken  up  separately,  after 
which  a  brief  statement  will  be  given  as  to  costs  of  manufacture. 

Burning  Practice  and  Theory. 

Before  taking  up  such  practical  questions  as  types  of  kiln  used, 
kinds  of  fuel,  relation  of  fuel  consumption  to  output,  etc.,  it  seems  ad- 
visable to  discuss  briefly  certain  more  theoretical  aspects  of  the  process 
of  burning.  On  examination,  however,  it  will  be  found  that  even  these 
apparently  theoretical  phases  of  the  subject  have  a  distinct  practical 
bearing. 

Chemical  changes  during  burning.  —The  rock  as  it  is  charged  into 
the  kiln  is  a  clayey  limestone,  consisting  essentially  of  lime  carbonate 
and  more  or  less  magnesium  carbonate,  with  clayey  matter  (silica, 
alumina,  and  iron  oxide).  In  addition  to  these  essential  ingredients 
it  will  usually  contain  a  few  per  cent  each  of  alkalies  (soda  and  potash), 
sulphur  or  sulphur  trioxide,  and  water.  During  calcination  certain 
chemical  changes  take  place  in  about  the  following  order. 

Any  mechanically  held  water  is  driven  off  before  the  rock  has  reached 
a  temperature  of  much  over  100°  C.  (212°  F.).  At  about  400°  C  mag- 
nesium carbonate  begins  to  be  dissociated,  its  carbon  dioxide  being 
driven  off  and  the  magnesia  remaining  in  its  caustic  and  active  form. 
When  mixed  with  lime  carbonate,  as  in  natural-cement  rock,  it  is  probable 
that  this  dissociation  does  not  take  place  much  below  700°  C.  When 
the  rock  reaches  750°  to  800°  C.  its  lime  carbonate  is  dissociated  in  like 
manner.  At  a  somewhat  higher  temperature  its  clay  is  decomposed 
and  combination  between  the  alumina  and  iron  oxide  and  the  lime  and 
magnesia  commences.  This  is  aided  by  the  presence  of  alkalies,  which 
here  act  as  fluxes. 

223 


224  CEMENTS,  LIMES,  AND  PLASTERS. 

It  is  probable  that  some  natural  cements  are  burned  at  tempera- 
tures not  exceeding  900°  C.;  in  which  case  their  strength  depends  largely 
on  the  formation  of  aluminates  and  ferrites.  When,  as  in  most  cases, 
the  temperature  is  carried  to  1100°-1300°  C.,  the  silica  is  attacked  and 
lime  and  magnesia  silicates  are  formed. 

Relation  of  composition  to  degree  of  burning. — It  may  be  set  down 
as  a  general  principle  that:  -'  .  ^ 

The  lower  the  Cementation  Index  the  higher  the  temperature  that  must 
be  reached  to  secure  thorough  combination. 

A  cement  with  an  index  of  2.00,  for  example,  can  be  burned  at  a 
temperature  little,  if  any,  above  that  of  an  ordinary  lime-kiln  (900°  C.), 
while  a  cement  whose  index  falls  below  1.10  will  require  a  temperature 
almost  equal  to  that  (2300°  F.)  attained  in  a  Portland-cement  kiln. 

There  are  therefore  distinct  economic  advantages,  so  far  as  fuel  con- 
sumption is  concerned,  in  making  a  cement  with  a  high  Cementation 
Index.  It  must,  however,  be  recollected  that  if  the  burning  is  properly 
done,  a  cement  of  low  index  will  be  stronger  than  one  of  high  index. 

By  far  the  most  satisfactory  proposition  to  handle,  from  the  manu- 
facturer's point  of  view,  is  a  product  whose  index  falls  between  1.20 
and  1.60.  Such  a  rock,  if  properly  burned,  will  give  a  cement  strong 
enough  to  compare  favorably  with  the  best  American  or  foreign  naturals, 
while,  on  the  other  -hand,  there  is  no  particular  danger  of  making  an 
unsound  product.  With  an  index  between  these  limits  the  burning 
temperature  may  vary  considerably,  one  way  or  the  other,  without  any 
danger  of  leaving  too  much  free  lime  or  magnesia  in  the  clinker.  With  a 
cement  whose  index  falls  below  1.10  this  i3  not  true,  for  the  margin  of 
safety  is  so  narrow  that  the  temperature  must  be  kept  up  to  its  highest 
point  under  penalty  of  producing  unsound  cement. 

Losses  in  burning,  etc. — If  all  the  rock  fed  to  the  kiln  were  perfectly 
burned,  the  loss  in  burning  would  correspond  directly  to  the  percentage 
of  carbon  dioxide  (C02)  plus  water  present  in  the  raw  rock.  On  this 
basis  one  ton  (2000  Ibs.)  of  rock  would  produce  the  number  of  barrels 
(280  Ibs.)  of  cement  given  in  Table  102. 

In  actual  practice,  however,  a  very  large  additional  percentage  must 
be  deducted  for  losses  by  everburning  or  underburning.  Bad  weather 
and  bad  management  may  carry  this  loss  from  clinkering  or  under- 
burning  to  a  point  where  one  third  of  the  product  of  the  kiln  is  spoiled. 
Iihproved  kilns  may  reduce  the  loss  from  these  causes  to  about  10 
per  cent,  and  anything  between  these  limits  (10  per  cent  and  33J  per 
cent)  may  be  expected  at  a  natural-cement  plant.  Under  average  con- 
ditions I  should  say  that  25  per  cent  would  be  a  safe  allowance. 


MANUFACTURE  OF  NATURAL  CEMENTS. 


225 


CO2+  water. 

Clinker. 

Cement. 

Per  Cent. 

Pounds. 

Barrels. 

25 

1500 

5.36 

26 

1480 

5.28 

27 

1460 

5.21 

28 

1440 

5.14 

29 

1420 

5.07 

30 

1400 

5.00 

31 

1380 

4.93 

32 

1360 

'  4.85 

33 

1340 

4.78 

34 

1320 

4.71 

35 

1300 

4.64 

36 

1280 

4.57 

37 

1260 

4.50 

38 

1240 

4.43 

39 

1220 

4.36 

40 

1200 

4.28 

Types  of  kiln  used. — With  but  few  exceptions  the  kilns  used  in  the 
American  natural-cement  industry  are  of  the  vertical  continuous  mixed- 
feed  type.*  That  is  to  say,  the  rock  and  fuel  are  fed  to  the  kiln  either 
mixed  together  or  in  alternate  layers.  Kilns  of  the  separate-feed  type, 
in  which  the  fuel  does  not  come  in  contact  with  the  rock  but  is  burned 
in  a  separate  furnace,  are  rarely  used  in  the  cement  industry.  In  the 
lime  industry  separate-feed  kilns  are  rapidly  supplanting  the  mixed- 
feed  kilns,  but  the  reasons  for  using  them  in  burning  \ime  do  not  hold 
in  burning  cement.  The  principal  advantage  of  the  separate-feed  kiln 
is  that  it  gives  a  clean  white  product  unmixed  with  fuel  ashes.  This 
is,  of  course,  a  distinct  advantage  to  a  lime  manufacturer,  but  it  would 
be  of  little  importance  in  the  cement  industry.  On  the  other  hand, 
the  mixed-feed  kilns  are  apparently  more  economical  of  fuel  than  the 
others. 

The  attention  of  American  natural-cement  manufacturers  might  be 
profitably  turned  to  consideration  of  some  of  the  improved  types  of 
continuous  kilns.  The  Aalborg  kiln,  for  example,  described  on  pages 
101-103,  is  used  in  hydraulic-lime  manufacture  in  Europe,  and  gives 
remarkably  good  results  as  to  fuel  consumption  and  quality  of  product. 

The  Campbell  kiln  is  not,  properly  speaking,  a  new  type  of  kiln,  but 
rather  a  kiln  containing  a  new  type  of  "pot".  In  the  ordinary  lime 

*  On  pp.  99  to  108  will  be  found  descriptions  of  the  various  types  of  kilns 
used  in  the  lime  industry.  These  descriptions  may  be  referred  to  as  being  of  in- 
terest in  the  present  connection. 


226 


CEMENTS,  LIMES,  AND  PLASTERS, 


or  natural-cement  kiln  the  pot  or  lower  portion  of  the  kiln  is  an  inverted 
oval  in  shape,  with  one  or  more  draw-chutes  or  doors  at  the  side.  This 
results  in  a  certain  amount  of  concentration  of  the  heat,  as  the  draft 
is  localized  near  the  base  of  the  kiln  owing  to  the  effects  of  the  draw- 
openings.  The  Campbell  kiln-pot,  instead  of  being  an  inverted  egg- 
shaped  mass  of  solid  masonry,  is  an  open  grating  in  the  form  of  an  in- 

f»  20' 

20' 


\\ 


< 8'6—  »--» 


FIG.  37. — Sections  of  kilns  used  in  natural-cement  plants.       (After  Gillmore.) 

verted  cone.  In  Figs.  38  and  39  the  construction  details  of  the  kiln 
are  clearly  shown.  It  will  be  seen  in  the  front  elevation  that  an  open 
space  is  left  all  around  the  pot,  between  the  grating  and  the  supporting 
walls  of  the  kiln,  so  that  the  drawer  has  free  access  to  all  parts  of  the 
grating  in  case  of  choking  or  other  difficulty.  The  openings  in  the  grating 
distribute  the  air-supply  so  that  the  draft  is  uniform  throughout  the 
kiln. 

It  is  stated  *  that  the  cost  of  reconstructing  the  iron-cased  kilns  of 
the  Milwaukee  Cement  Company  on  the  Campbell  pattern  was  about 
$250  per  kiln.  For  a  stone  kiln  the  cost  of  reconstruction  would  be 
somewhat  higher.  A  new  Campbell  kiln,  however,  would  cost  some- 
what less  than  a  new  kiln  of  ordinary  pattern,  for  the  iron  "pot"  will 
displace  more  than  its  equivalent  value  of  brick  and  labor. 

The  Campbell  kilns  in  use  at  the  plant  of  the  Milwaukee  Cement 
Company  hold  a  charge  equivalent  to  about  400  barrels  (265  Ibs.  each) 
of  cement.  This  is  drawn  at  the  rate  of  125  to  130  barrels  per  day, 


*  Engineering  News,  Dec.  23,  1897. 


MANUFACTURE  OF  NATURAL  CEMENTS. 


227 


FRONT  ELEVATION  SECTION 

FIG.  38.— Elevation  and  section  of  the  Campbell  kiln. 


g    S3 


-92" 


TOP  RING 


DOOR  FRAME 


PLAN 


FIG.  39. — Plan  and  details  of  the  Campbell  kiln. 


228 


CEMENTS,  LIMES,  AND  PLASTERS. 


all  the  drawing  for  the  day  being  done  in  ten  hours.  Nut  and  slack 
coal,  mixed,  are  used  for  fuel.  The  fuel  consumption  amounts  to  about 
30  Ibs.  per  barrel  of  cement,  equivalent  to  11.3  per  cent  on  the  weight 
of  the  cement  produced. 

At  the  Pembina  plant  in  North  Dakota  a  kiln  40  feet  high  and  10  feet 
in  external  diameter  is  used.  The  shell  is  of  J-inch  No.  14  boiler  iron. 
The  klin  space  is  broadest  at  the  top,  /narrows  about  6  feet  down  to  a 


FIG.  40.— Kilns  of  the  Lawrence  plant,  Siegfried,  Pa. 

throat  about  6  feet  in  diameter,  below  which  it  again  enlarges,  reaching 
almost  to  the  kiln-shell  at  15  feet  above  the  base.  Below  this  it  is  again 
somewhat  contracted  to  the  drawing  level.  The  kiln  space  is  lined  with 
8-inch  fire-brick  and  the  space  between  these  brick  and  the  kiln-shell 
is  filled  with  ashes.  This  kiln  produces  about  50  barrels  of  265  Ibs. 
each  per  day,  with  a  fuel  consumption  of  one  ton  of  Youghiogheny  slack'. 
Lignite  slack,  mixed  half  and  half  with  Youghiogheny  slack,  has  been  used 


MANUFACTURE  OF  NATURAL ;'  CEMENTS. 


229 


at  times,  and  apparently  gives  almost  as  good  results  as  the  bituminous 
slack  alone.  About  10  per  cent  of  the  total  product  is  underburnt,  or 
clinkered.  This  record  is  about  equivalent  to  £  fuel  consumption  of 
40  Ibs.  per  barrel,  or  15.1  per  cent,  on  the  weight  of  cement  produced. 
This  is  rather  high  fuel  consumption  for  natural  cement,  but,  on  the 
other  hand,  the  product  is  of  peculiarly  high  grade,  passing  most  Portland 
standards. 

The  natural-cement  kilns  at  one  of  the  prominent  Lehigh  district 
plants  are  about  30  feet  in  height  and  of  circular  cross-section.  In- 
ternally they  are  almost  exactly  cylindrical,  being  10  feet  in  diameter 
at  the  top  and  9J  feet  in  diameter  at  the  base.  The  cement  rock  and 


FIG.  41. — Kilns  and  coal-conveyor  of  the  Speed  plant,  Speeds,  Ind. 

fuel  are  fed  in  alternate  layers,  the  fuel  being  anthracite  coal  broken 
to  about  J-inch  size.  From  35  to  50  Ibs.  of  coal  are  required  to  burn 
one  barrel  (300  Ibs.)  of  cement,  corresponding  to  a  fuel  consumption  of 
11.6  to  16.7  per  cent  of  the  weight  of  cement  produced. 

Two  styles  of  kiln  are  in  use  in  the  Louisville  district.  The  older 
and  smaller  kilns  are  36  feet  in  height,  8  feet  in  diameter  at  the  top, 
enlarging  to  12  feet  at  a  point  24  feet  above  the  base  and  again  con- 
tracting to  4  feet  at  the  base.  These  are  drawn  from  a  chute  by  use 
of  a  swinging  gate  or  apron.  Coal  and  rock  are  charged  in  alternate 


230 


CEMENTS,  LIMES,  AND   PLASTERS. 


layers.  About  a  week  suffices  for  the  passage  through  the  kiln  of  any 
particular  mass  of  material.  These  small  kilns  produce  about  100  to 
125  barrels  (265  Ibs.  each)  of  cement  per  day. 

The  larger  kilns  are  54  feet  from  extreme  base  to  top.  Viewed 
from  the  outside  they  appear  to  be  cylinders  54  feet  high  and  16  feet 
in  diameter.  Their  interior  space,  however,  is  10  feet  in  diameter  at 
the  top,  enlarging  to  12  feet  at  a  poinUlS  feet  above  the  base.  Below 
this  level,  though  the  interior  walls  still  slope  outward,  the  space  is 
really  contracted  by  the  occurrence  of  a  conical  mass  of  brickwork  in 
the  center  of  the  kiln.  This  cone  throws  the  downcom^ng  clinker  toward 
the  draw-gates  at  the  sides.  A  9-inch  lining  of  fire-brick  is  set  around 
the  kiln  space  proper.  This  is  followed  by  9  inches  of  common  brick, 
and  the  space  between  the  common-brick  lining  and  the  exterior  kiln 
shell  (which  is  |-inch  iron)  is  filled  with  clay.  A  kiln  of  this  size  and 
type  will  produce  150  barrels  of  cement  per  day. 


FIG.  42. — Kilns  and  kiln-housing,  Speed  plant,  Speeds,  Ind. 

The  coal  used  in  these  kilns  is  bituminous  nut  and  slack  mixed  from 
Pittsburg  or  Jellico.  About  25.6  Ibs.  of  coal  are  required  to  burn  a 
barrel  of  cement  (265  Ibs.),  equivalent  to  a  fuel  consumption  of  about 
9.5  per  cent  on  weight  of  cement  produced. 


MANUFACTURE  OF  NATURAL  CEMENTS.          231 

In  the  Rosendale  district  cylindrical  kilns  are  used.  These  vary 
from  8  to  12  feet  in  diameter  and  from  20  to  36  feet  in  height.  A  kiln 
fed  with  one  half  ton  of  anthracite,  pea  size,  will  give  75  to  80  bar- 
rels of  cement  per  day.  This  is  equivalent  to  a  fuel  consumption  of 
about  7  per  cent  on  the  weight  of  cement  produced.  From  one  fifth 
to  one  third  of  the  total  produce  of  the  kiln  may  be  overburned  clinker 
or  underburned  rock.  This  item,  however,  depends  largely  upon  the 
skill  of  the  burners,  though  it  is  also  affected  by  uncontrollable  factros, 
such  as  temperature,  weather  conditions,  force,  and  direction  of  the 
wind,  etc. 

The  kilns  in  use  in  the  Utica  district  in  Illinois  are  elliptical  in  cross- 
section  (plan),  with  vertical  walls.  The  largest  kilns  of  this  type  are 
30  feet  in  their  longest  inside  diameter  and  12  feet  wide.  Their  total 
height  with  foundation  is  50  feet,  giving  a  clear  height  of  45  feet  from 
bottom  of  draw-hole  to  top  of  kiln.  These  kilns  turn  out  400  barrels 
(265  Ibs.  each)  of  cement  per  day,  taking  18  to  20  Ibs.  of  coal  per  barrel 
of  cement.  This  corresponds  to  a  fuel  consumption  of  only  6.8  to  7.5 
per  cent. 

The  second  size  of  Utica  kilns  is  20  feet  by  9  feet  in  its  inside  diam- 
eters. The  smallest  size  is,  like  the  others,  elliptical,  with  inside  diam- 
eters of  14  and  7  feet,  respectively,  and  a  height  of  32  feet  from  top 
of  bridge  wall  to  top  of  kiln.  These  kilns  turn  out  300  to  375  barrels 
per  day. 

All  the  diameters  quoted  above  are  internal  measurements.  The 
kiln-shell  proper  is  of  J-inch  sheet  iron.  This  is  lined,  successively,  with 
an  18-inch  layer  of  ashes,  18  inches  of  stone  or  common  brick,  and 
9  inches  of  fire-brick. 

The  kilns  in  the  central  New  York  district  are  described  *  as  egg- 
shaped,  10  feet  in  diameter  at  the  top,  12  feet  at  the  middle,  and  3J 
feet  at  the  bottom,  with  a  height  of  28  to  42  feet.  "There  are  usually 
several  kilns  built  together  in  an  embankment  of  very  heavy  masonry, 
so  constructed  against  a  hillside  that  the  raw  material  can  be  conven- 
iently conveyed  there  from  the  quarry  and  the  burned  cement  easily 
removed  from  the  bottom  of  the  kiln."  The  kilns  are  built  of  lime- 
stone and  lined  either  with  sandstone  or  fire-brick.  "When  a  kiln 
is  ready  to  be  filled  a  cord  of  dry,  hard,  4-foot  wood  is  put  into  the  bot- 
tom and  covered  4  inches  deep  with  coarse  anthracite  coal,  then  a 
layer  1  foot  thick  of  cement  rock,  succeeded  by  another  layer  of  coal 

*  Luther,  D.  D.     The  Economic  Geology  of  Onondaga  County,  New  York. 
15th  Ann.  Rept.  N.  Y.  State  Geologist,  vol.  1,'pp.  241-303.     1897. 


232  CEMENTS,  LIMES,  AND  PLASTERS. 

partly  coarse  and  partly  fine.  This  is  repeated  till  the  kiln  is  filled 
to  the  top,  which  required  about  10  tons  of  coal  and  15  cords  of  stone, 
equal  to  1500  bushels  of  cement.  Then  the  fire  is  started  at  the  bottom 
and  gradually  works  its  way  upward  until  the  whole  mass  is  glowing 
with  heat.  After  two  or  three  days  the  gate  or  door  in  the  bottom  is 
opened  and  through  it  the  burned  cement  rock  is  drawn  to  the  amount 
of  250  to  300  bushels  per  day,  fresh  ,-eoal  and  rock  being  constantly 
added  to  keep  the  kiln  full  to  the  top.  One  cord  of  cement  rock  makes 
100  bushels  of  cement." 

Bles  states  that  two  types  of  kilns  are  in  use  at  the  Cummings 
plant  at  Akron,  Erie  County,  N.  Y.  Of  seventeen  kilns  in  use  there 
at  the  time  of  his  visit,  eight  were  of  rectangular  cross-section,  9  by  22 
feet  in  area,  with  a  height  of  34  feet.  The  remaining  nine  were  cir- 
cular in  cross-section,  with  a  diameter  of  9  feet  and  a  height  of  34 
feet. 

Two  types  of  kilns  are  in  use  in  the  Fort  Scott  district,  Kansas.  The 
more  common  type  is  cylindrical,  10  to  12  feet  in  diameter  and  30  to  40 
feet  in  total  height.  The  lower  10  feet  or  so  is  of  stone,  on  which  is  set 
the  kiln  proper.  This  is  constructed  of  ^-inch  sheet  iron,  lined  with 
successive  layers  of  coal  ashes,  clay,  common  brick  and  fire-brick.  These 
kilns  are  drawn  daily,  and  yield  60  to  75  barrels  of  cement  each  per 
day.  The  fuel  used  is  slack  coal,  either  Arkansas  semi-bituminous  from 
Poteau  or  Huntingdon  or  a  very  sulphurous  local  coal  which  under- 
lies the  cement  rock  at  Fort  Scott.  The  coal  is  fed  with  the  rock,  and 
is  used  at  the  rate  of  30  to  35  Ibs.  per  barrel  of  cement,  equal  to  a  fuel 
consumption  of  11.3  to  13.2  per  cent  on  the  weight  of  cement  produced. 
At  a  three-kiln  plant  the  burning  is  managed  by  five  men — two  feeding 
and  three  drawing  the  kilns. 

At  one  of  the  Fort  Scott  plants  four  flame-kilns  are  also  in  use.  Those 
have  separate  fireplaces,  so  that  the  fuel  and  cement  do  not  come  into 
contact.  Lump  coal  must  be  used  for  these  kilns,  and  they  are  said 
to  be  more  expensive,  both  in  labor  and  fuel,  than  the  type  above 
described. 

The  kilns  at  the  plant  of  the  Howard  Cement  Company,  in  Georgia, 
are  of  the  familiar  dome  type  commonly  used  in  lime  and  natural- 
cement  burning,  and  are  six  in  number.  Four  are  jacketed  with  steel 
and  lined  with  fire-brick,  the  space  between  the  jacket  and  the  lining 
being  filled  with  clay.  The  two  remaining  kilns  differ  from  these  only 
in  the  fact  that  in  place  of  the  steel  jacket  their  exterior  surfaces  are 
laid  up  with  rock.  These  rock-jacketed  kilns  are  said  to  be  somewhat 
more  satisfactory  than  those  of  the  steel- jacketed  type. 


MANUFACTURE  OF  NATURAL  CEMENTS. 


233 


All  the  kilns  are  25  feet  in  height  and  have  an  output  of  60  barrels 
of  cement  each.  The  kilns  are  charged  to  the  top  with  fuel  and  cement 
rock,  in  the  proportion  of  about  300  Ibs.  of  fuel  to  2500  Ibs.  of  rock. 
The  fuel  used  is  coal,  the  sizes  being  nut,  pea,  and  slack  in  about  equal 
amounts.  Seven  or  eight  days  are  required,  on  the  average,  to  "turn 
a  kiln",  including  charging,  burning,  and  drawing.  This  corresponds 
to  a  fuel  consumption  of  about  18  per  cent  on  the  weight  of  cement 
produced.  In  explanation  of  this  high  fuel  accqunt,  the  reader  is 


FIG.  43. — Kilns  and  loading-tracks,  Fort  Scott,  Kan. 

referred  to  the  discussion  on  page  224,  where  it  is  shown  that  the  amount 
of  fuel  used  necessarily  increases  with  the  percentage  of  lime  and  mag- 
nesia. A  high-limed  cement — and  the  Howard  cement  is  exception- 
ally high  in  lime — therefore  requires  a  very  high  fuel  consumption. 

Fuel  consumption. — The  fuel  consumption  in  natural-cement  plants 
is  extremely  variable,  as  is  shown  by  the  results  tabulated  below.  The 
variation  is  caused  in  some  parts  by  differences  in  kiln  management 
and  character  of  fuel,  but  more  largely  to  differences  in  the  composi- 
tion of  the  cement.  The  cements  of  lowest  index  demand  calcination 
at  high  temperatures,  while  those  of  high  index  may  be  burned  at  very 
low  temperature. 


234 


CEMENTS,  LIMES,  AND  PLASTERS 


TABLE    103. 
FUEL  CONSUMPTION  IN  AMERICAN  NATURAL-CEMENT  PLANT& 


Mill. 

Kind  of  Fuel. 

Pounds  Fuel 
per  100  Lbs. 
Cement. 

A 
B 

Bituminous  nut  and  slajck  
Coke              '  

9.5 
10.0-16.7 

o 

Bituminous  nut  and  slack  

11.3 

Bituminous  slack 

11  3-13.2 

Anthracite  nut                           .  . 

11.6-16.7 

F 

Bituminous  slack               

151-1 

G 

Anthracite  nut               

17.8 

H 
I 

Bituminous  nut,  pea,  and  slack  .  . 
Anthracite  pea  

18.0 
7.0 

j 

6.6 

Anthracite  pea  and  slack  ...... 

22.0 

Hard  and  soft  clinker. — When  a  natural-cement  kiln  is  drawn,  part 
of  the  product  will  consist  of  hard,  clinkered  material,  part  of  softer, 
porous,  moderately  burned  stuff,  and  part  of  cores  and  masses  of  prac- 
tically unburned  rock.  The  relative  proportions  in  which  these  three 
grades  are  present  will  be  determined  by  the  type  of  kiln  and  the 
care  with  which  the  burning  has  been  conducted.  The  differences  in 
burning  are  of  course  due  to  some  extent  to  the  fact  that  the  masses 
of  rock  fed  into  the  kiln  differed  among  themselves  in  composition;  but 
they  are  mostly  due  to  the  different  extent  to  which  the  masses  have 
been  exposed  to  the  heat  of  the  fuel. 

The  facts  above  stated  are  obvious  enough,  and  the  matter  might 
be  passed  over  without  further  notice  if  it  were  not  the  case  that  with 
some  rocks  the  clinkered  product  will  give  the  best  cement,  while  wi£h 
other  rocks  the  medium-burned  part  of  the  product  is  the  best.  This 
fact  certainly  requires  both  consideration  and  explanation. 

The  facts  themselves  are  beyond  question.  In  the  Rosendale  dis- 
trict, for  example,  from  10  to  20  per  cent  of  the  output  of  the  kiln  is 
clinkered  material.  This  clinker  is  thrown  away,  for  experiments 
have  shown  that  it  does  not  give  a  cement  nearly  as  good  as  the  mod- 
erately burned  product.  In  the  Akron-Buffalo  district,  on  the  other 
hand,  the  hard,  clinkered  parts  of  the  product  are  carefully  separated 
and  ground;  for  experience  has  shown  that  these  clinkers  give  a  much 
stronger  cement  than  the  softer,  more  porous  masses.  These  separate 
facts  have  been  noted  by  many  writers,  but  no  explanation  has  been 
offered. 


MANUFACTURE  OF  NATURAL  CEMENTS.         235 

The  following  seems  to  explain  the  difference  in  practice  satisfac- 
torily. It  has  been  noted  above  that  the  lower  the  Cementation 
Index  the  higher  the  temperature  necessary  to  secure  perfect  combina- 
tion of  the  lime  and  clay.  The  Rosendale  rock,  where  the  Cementa- 
tion Index  averages  around  1.50,  will  therefore  be  properly  burned 
at  a  much  lower  temerature  than  the  Akron  rock,  where  the  index  falls 
below  1.10.  But  a  low  temperature  means  low  fuel  costs,  and  so  there 
is  not  the  temptation  to  economize  on  fuel  in  burning  a  rock  of  high 
index  that  there  is  in  burning  one  of  low  index.  When  rocks  of  high 
index  are  burned,  therefore,  the  temperature  and  the  fuel  supply  will 
often  be  allowed  to  exceed  their  proper  amount,  resulting  in  the  pro- 
duction of  clinkered  material  which  has  been  burned  higher  than  was 
necessary  and  is  therefore  inferior.  But  in  burning  a  rock  of  low  index, 
it  will  be  necessary  to  almost  clinker  the  material  before  perfect  com- 
bination is  secured.  Because  of  the  natural  tendency  to  economize 
on  fuel,  the  temperature  will  usually  be  carried  a  little  lower  than  is 
necessary.  The  result  is  that  in  burning  rocks  of  low  index  the 
clinkered  material  is  correctly  burned  and  gives  the  best  cement,  while 
the  softer  masses  are  really  underburned  and  therefore  inferior. 

The  respective  values  of  the  hard  and  soft  parts  of  the  product 
will  therefore  depend  on  the  Cementation  Index.  The  following  seems 
a  fairly  satisfactory  statement  of  the  case. 

(a)  When  burning  a  product  having  an  index  lower  than  1.10,  the 
clinkered  portions  will  furnish  the  best  cement.  If  separated  and 
ground  to  proper  fineness,  they  will  give  a  cement  approximating  to 
Portland  in  its  physical  properties. 

(6)  When  burning  a  product  where  the  index  is  between  1.10  and 
1.25,  the  clinkered  portions  and  the  softer  masses  will  probably  be -of 
almost  equal  value. 

(c)  When  burning  a  product  where  the  index  is  above  1.25,  the 
clinkered  portions  may  be  rejected  as  worthless;  and  when  the  index 
rises  above  1.60,  even  some  of  the  softer  masses  may  be  overburned, 
unless  the  temperature  be  kept  sufficiently  low. 

Seasoning  and  slaking. — It  is  obvious  that  in  burning  a  natural 
rock  in  a  kiln  whose  temperature  cannot  be  controlled  closely,  there 
are  opportunities  for  great  differences  between  the  degree  of  burning 
which  the  rock  should  have  received  and  the  degree  which  it  actually 
does  receive.  When  the  Cementation  Index  of  the  product  is  very 
high — over  1.60  for  example — even  a  light  burning  will  suffice  to  decar- 
bonate all  of  the  limestone  and  to  secure  combination  of  the  lime  with 
the  clayey  matter.  This  is  especially  true  if  the  silica  is  comparatively 


236  CEMENTS,  LIMES,  AND  PLASTERS. 

low  and  the  alumina  and  iron  oxide  high.  A  rock  of  this  general 
type  can  therefore  vary  quite  widely  in  composition  and  degree  of  burn- 
ing without  running  any  risk  of  turning  out  an  unsound  product. 

As  the  percentages  of  lime  and  magnesia  rise,  however,  the  prob- 
lem becomes  more  difficult,  and  when  the  index  falls  below  1.20  a  com- 
paratively slight  variation  in  the  composition  of  the  rock  or  in  the 
degree  to  which  it  is  burned"  is  apt  to*  give  a  product  containing  too 
much  free  lime  for  safety. 

When  this  condition — the  presence  of  free  lime  or  magnesia  in  the 
product — occurs  frequently,  the  manufacturer  has  three  options.  He 
may  (1)  burn  at  a  higher  temperature,  (2)  look  for  a  lower-lime  rock, 
or  (3)  slake  the  free  lime  in  some  way.  The  first  choice  would  usually 
be  the  best,  but  in  nine  cases  out  of  ten  the  manufacturer  will  take 
the  third,  as  being  apparently  the  cheapest. 

Free  lime  in  a  natural  cement  may  be  neutralized  either  by  aerating 
the  ground  cement  or  by  sprinkling  or  steaming  the  unground  clinker. 
When  aeration  is  practiced,  the  ground  cement  must  be  exposed  to 
the  air  as  freely  as  possible.  This  implies  that  it  should  be  spread 
out,  rather  than  placed  in  deep  bins,  and  consequently  requires  con- 
siderable floor-space  and  manual  labor.  Steaming  or  sprinkling  the 
unground  clinker  requires  less  space  and  labor,  but  care  must  be  taken 
that  excess  of  steam  or  water  is  not  allowed  to  reach  the  cement.  The 
ideal  aimed  at  is  to  supply  sufficient  moisture  to  slake  the  free  lime, 
but  to  leave  the  aluminates  and  silicates  untouched.  Simple  storage 
of  the  clinker,  with  free  access  to  the  air,  will  often  accomplish  this 
result.  An  incidental  benefit  to  the  manufacturer  which  comes  from 
slaking  the  clinker  (either  by  steaming,  sprinkling,  or  storage)  lies  in 
the  fact  that  the  lime  in  slaking  helps  to  disintegrate  the  clinker  and 
thus  reduce  the  cost  of  grinding. 

Grinding  the  Clinker. 

When  natural  cement  was  first  manufactured  in  this  country,  the 
millstones  used  at  flour-mills  were  the  only  available  fine  grinders. 
Grinding  practice  at  natural-cement  plants  was  therefore  soon  estab- 
lished in  a  form  which  has  persisted  at  many  plants  to  the  present 
day.  Even  now  a  few  small  plants,  I  believe,  grind  natural  cement 
and  flour  in  the  same  building  at  different  times  of  the  year. 

Until  quite  recently,  grinding  practice  was  almost  uniform.  The 
burned  rock  was  sledged  if  necessary,  fed  through  a  cracker  or  other 
comparatively  coarse  reducer,  and  finished  on  millstones  of  one  type 


MANUFACTURE  OF  NATURAL  CEMENTS, 


237 


or  another.  Within  the  past  few  years  modern  grinding  machinery 
has  been  introduced  at  a  few  plants  and  has  given  such  satisfactory 
results  that  no  natural-cement  manufacturer  can  afford  to  disregard 
the  innovations. 

The  gain  •  in  strength  due  to  increased  fineness  of  grinding  is  well 
shown  by  the  following  data,  for  which  I  am  indebted  to  the  Western 
Cement  Company,  of  Louisville,  Ky.  A  year  or  two  ago  this  com- 
pany replaced  millstones  in  one  of  its  best  plants  by  tube  mills,  and 
increased  the  fineness  from  about.  76  per  cent  through  a  100-mesh  sieve 
to  about  90  per  cent  through  100-mesh.  With  mortar  briquettes, 
1  cement  and  2  sand,  this  gave  the  following  results: 


Fineness 
through 
100-mesh. 

7  Days. 

28  Days. 

76  per  cent 
90    "      " 

63  Ibs. 
128  " 

124  Ibs. 
188    " 

Actual  mill  equipments. — The  variations  in  practice  which  now 
exist  can  best  be  understood  by  reference  to  the  following  data  on  the 
actual  equipments  of  a  number  of  the  best  American  mills: 


Mill 

1. 

a. 

I 

6. 

2 

c. 

2 

Mill 

2. 

a. 

5 

b. 

16- 

Mill 

3. 

a. 

1 

b. 

1 

c. 

1 

Mill 

4. 

a. 

1 

b. 

1 

Mill 

5. 

a. 

St 

b. 

Cu 

c. 

10- 

d. 

10- 

Mill 

6. 

a. 

Po 

b. 

Es 

Mill 

7. 

a. 

1 

b. 

2 

c. 

1 

Mill 

8. 

a. 

1 

b. 

1 

Mill 

9. 

a. 

St< 

b. 

Gr 

1  Gates  crusher 

2  Lindhard  kominuters. 
2  Davidsen  tube  mills. . 
5  McEntee  crackers.  .  .  . 

16-run  Esopus  millstones 

1  coarse  pot  crusher 

1  fine  pot  crusher 

1  Williams  mill.  . 

1  Williams  mill 1 

1  16-foot  Bonnot  tube  mill —  J 
Sturtevant  crushers. 
Cummings  grinders. 
10-run  millstones,  iron  plates. 
10-run  Esopus  millstones. 
Pot  crushers. 
Esopus  millstones. 

1  Gates  crusher -j 

2  dry-pans J- 

1  Davidsen  tube  mill J 

1  pot  crusher \ 

1  Williams  mill J 

Stedman  disintegrators. 
Griffin  mills. 


1500  bbls.  per  day. 

}  1600  bbls.  per  day. 

200  bbls.  per  day 
(run  only  about 
one  third  time). 

100  bbls.  per  day. 


800  bbls.  per  day. 
500  bbls.  per  day. 


238  CEMENTS,  LIMES,  AND   PLASTERS. 

Types  of  grinding  machinery  employed. — In  Chapter  XXXV,  where 
the  crushing  and  grinding  machinery  used  in  Portland-cement  plants  is 
described  in  detail,  a  classification  of  these  machines  is  introduced  as 
a  guide  to  the  descriptions  of  individual  machines.  As  all  but  one 
of  the  groups  there  distinguished  are  represented  by  ©ne  or  more 
machines  used  in  natural-cement  mills,  the  same  grouping  will  be  used 
in  the  present  chapter.  It  is  as  follows: 

Class  1.  JAW  CRUSHERS;   material  crushed  between  two  jaws  which  approach 

and  recede f  . .  BLAKE  CRUSHER. 

Class  2.  CONE  GRINDERS;  material  crushed  by  revolution  of  a  toothed  cone  or 

spindle  within  a  toothed  cup GATES  CRUSHER,  CRACKERS. 

Class  3.  ROLLS;    material   crushed  between  two  or  more  plain,   fluted,  or 

toothed  cylinders  revolving  in  opposite  directions. 
Class  4.  MILLSTONES;   material  crushed  between  two  flat  or  grooved  discs,  one 

of  which  revolves. 

MILLSTONES,  BUHRS,  STURTEVANT  EMERY  MILL,  CUMMINGS  MILL. 
Class  5.  EDGE-RUNNERS;  material  crushed  in  a  pan  under  a  cylindrical  turning 

on  a  horizontal  axis  and  gyrating  about  a  vertical  axis. 

EDGE-RUNNERS,  DRY-PANS. 
Class  6.  CENTRIFUGAL  GRINDERS;    material  crushed  between  rollers  and  an 

annular  die,  against  which  the  rollers  are  pressed  by  centrifugal 

force. 

HUNTINGDON  MILL,  GRIFFIN  MILL,  NAROD  MILL,  CLARK  PULVERIZER. 
Class  7<,  BALL  GRINDERS;   material  crushed  by  balls  or  pebbles  rolling  freely 

in  a  revolving  horizontal  cylinder. 

KOMINUTER,   BALL  MILL,  TUBE  MILL. 

Class  8.  IMPACT  PULVERIZERS;   material  crushed  by  a  blow  in  space  delivered 
by  revolving  hammers,  bars,  cups,  or  cages. 

WILLIAMS  MILL,  RAYMOND  PULVERIZER,  STURTEVANT  DISINTE- 
GRATOR, CYCLONE  PULVERIZER. 

Jaw  crushers. — So  far  as  known  to  the  writer  no  jaw  crushers  of 
the  Blake  type  are  at  present  used  in  natural-cement  plants.  At  one 
plant,  and  possibly  at  others,  the  Sturtevant  roll- jaw  crusher  is  in  use 
as  a  preliminary  reducer  on  clinker. 

Cone  grinders. — Though  the  heavier  crushers  of  this  class,  such  as 
the  Gates  crushers,  are  used  at  but  few  natural-cement  plants,  the  group 
includes  a  series  of  machines  which  have  always  been  held  in  favor  as 
preliminary  reducers  on  natural-cement  clinker — the  so-called  " crackers". 

The  "crackers"  so   extensively  used  in  the  natural-cement  indus- 


MANUFACTURE  OF  NATURAL  CEMENTS.  239 

try,  of  which  the  McEntee  cracker  of  the  Rosendale  district  may  be 

taken   as   typical,   differ  but   little   in   design. 

They   consist,    as   shown   in   Fig.    44,    of   two 

concentric  cone-shaped  castings,  both  provided 

on   their   adjacent    surfaces   with   a   series    of 

grooves    and  flanges.      Gillmore    states  *  that 

the   elements   of   the   lower   portions   of  both 

cones  make  a  smaller  angle  with  the  common 

axis  than  the  elements  of  the  upper  portions, 

with  a  view  to  lessen  the  strain  and  the  effects 

of  sudden  shocks  on  the  machinery  by  secur- 
ing a  more  gradual  reduction  of  the  stone  to 

the  required  size.     These  lower  portions,  being 

subject  to  very  rapid  wearing,  are  made  of  FlG  44._s7^tions  of 
chilled  iron,  and  are  moreover  cast  in  separate  cracker  used  in  grinding 

pieces,  in  order  that  they  may  be  replaced  by  ^J^f*6**'  (After 
new  ones  as  occasion  requires.  The  greatest 

diameter  of  the  core  at  the  top,  including  the  flanges,  is  9  inches,  at 
the  bottom  5i  to  6  inches,  and  its  height  is  15  or  16  inches.  The 
diameter  of  the  shell,  measured  within  the  largest  flanges,  is  14  to  15 
inches  at  the  top  and  a  trifle  greater  than  that  of  the  core  at  the  bot- 
tom, while  its  height  is  16J  to  18  inches.  One  cracker  of  this  size, 
working  with  a  velocity  of  80  to  85  revolutions  per  minute,  is  sufficient 
for  a  mill  grinding  250  to  300  barrels  per  day.  It  is  customary  to  pro- 
vide one  cracker  for  every  two  run  of  millstones.  In  the  data  given 
on  page  237  it  will  be  noted  that  each  of  the  heavier  McEntee  crackers 
now  in  use  is  expected  to  supply  three  run  of  millstones. 

Rolls. — Rolls  are  not  used  in  any  American  natural-cement  plant. 
Millstones. — This  group  includes  a  series  of  mills  very  important  in 
natural-cement  practice.  The  ordinary  millstones  and  buhrstones 
have  been  used  in  this  industry  since  its  commencement  in  1818,  while 
the  Sturtevant  " rock-emery"  mill  and  the  Cummings  grinder  repre- 
sent modern  types. 

Ordinary  millstones  are  cheap  in  first  cost,  but  require  considerable 
attention  for  dressing,  etc.  They  vary  in  diameter  from  3  to  5  feet,  and 
will  grind  from  6  to  10  barrels  of  cement  per  hour  to  a  fineness  of  90  per 
cent  through  50-mesh.  When  greater  fineness  is  required,  however, 
millstones  cannot  do  the  work  economicallv. 


*  "Limes,  Hydraulic  Cements,  and  Mortars  ",  p.  160, 


240 


CEMENTS,  LIMES,  AND   PLASTERS. 


In  the  Sturtevant  rock-emery  mill  the  ordinary  millstones  or  buhr- 
stones  are  replaced  by  a  " rock-emery"   stone.     This  is  composed  of 


FIG.  45. — Sturtevant  horizontal  rock-emery  mill. 

a  circular  iron  cup  or  shell.    The  center  of  the  circle  is  made  up  of  a 
disc  of  buhrstone    while  the  portion  nearer  the  rim  is  set  with  slabs 


FIG.  46. — Sturtevant  rock-emery  millstone. 

of  "rock  emery"  cemented  by  metal  poured  in  while  molten.  Radial 
strips  of  buhrstone  are  set  so  as  to  continue  the  furrows  of  the  cen- 
tral buhrstone  to  the  rim  of  the  wheel.  This  is  shown  in  Fig.  46.  The 


MANUFACTURE  OF  NATURAL  CEMENTS. 


241 


idea  is  to  prevent  unequal  wear,  for  in  an  ordinary  millstone  the  rim 
wears  much  faster  than  the  central  area.  These  rock-emery  millstones 
are  listed  by  the  manufacturers  at  the  following  prices  per  pair,  f.  o.  b. 
Boston : 

*                                             30-inch $100 

36-  "    150 

42-  "    200 

48-  "    250 

54-  "    300 

The  Sturtevant  rock-emery  mill  itself,  which  uses  the  stones  above 
described,  is  made  both  as  a  vertical  and  horizontal  mill,  the  latter  being 
preferable  for  harder  work.  The  horizontal  mill  is  shown  in  Fig.  45, 
and  a  section  of  it  is  given  in  Fig.  47.  It  is  made  only  in  42-inch  size, 
with  under-runner  stone.  The  running  stone,  the  under  one  in  this 
mill,  is  rigidly  fixed  to  the  head  of  the  large  vertical  shaft,  which  is 
made  to  revolve  by  a  pulley  placed  on  it  below  the  millstones. 

A  mill  of  this  size  will  grind  from  15  to  20  barrels  of  cement  per  hour, 
taking  15  to  20  H.P.  in  doing  so. 


FIG.  47. — Section  of  Sturtevant  horizontal  mill. 

The  Cummings  grinder  *  crushes  material  between  two  vertical 
chilled-iron  discs,  one  of  which  is  stationary,  while  the  other  is  revolved 
at  high  speed.  The  faces  of  both  discs  are  cut  into  a  series  of  bands 

*  Ball,  C.  M.      The  Cummings  ore-granulating  mill.     Trans.  Amer.  Institute 
Mining  Engrs-,  *ol.  21,  pp.  516-519.     1893. 


242  CEMENTS,  LIMES,  AND   PLASTERS. 

and  farrows,  and  the  material  fed  between  them  is  disintegrated  rapidly. 
It  is  stated  that  this  mill,  when  working  on  hard  natural-cement  clinker, 
has  given  very  satisfactory  results.  "The  clinker  is  fed  to  the  mill 
broken  to.  about  the  size  of  1-inch  cubes,  and  is  reduced  to  about  the 
size  of  wheat,  and  from  that  down  to  dust,  at  the  rate  of  20  tons  per 
hour.  This  work  requires  50  horse-power.  In  a  trial  this  mill  has 
reduced  natural  cement  (taken'  direct  Jtrom  the  kilns,  with  the  softer 
portions  mixed  with  the  clinker,  the  latter  amounting  to  about  one 
third  of  the  total)  at  the  rate  of  1300  Ibs.  per  minute,  the  product  pass. 
ing  50-mesh  wire  screens.  The  cost  of  renewal  of  tjhe  grinding  plates 
has  been  $10  per  month,  no  other  repairs  being  necessary".  Using 
the  data  above  quoted  as  bases  for  calculation,  it  may  be  seen  that 
the  Cummings  grinder,  when  used  as  a  coarse  reducer,  taking  mate- 
rial of  1  inch  size  and  reducing  it  to,  say,  &  inch,  requires  2.7H.P.  hours 
per  barrel  (300  Ibs.)  cement.  When  used  as  a  complete  grinder,  taking 
coarse  clinker  and  reducing  it  all  to  pass  50-mesh,  it  requires  5.2  H.P. 
hours  per  barrel  of  cement. 

Though  no  direct  statement  is  made  by  Mr.  Ball,  it  is  perhaps  fair 
to  assume  that  the  trial  noted  above  took  place  at  the  mill  of  the  Cum- 
mings Cement  Company  in  Akron,  N.  Y.  The  following  description 
of  the  reduction  practice  there  will,  therefore,  be  of  interest  in  this 
connection.  It  must  be  recollected  that  the  cement  rock  of  western 
New  York  is  of  very  low  index,  and  that  the  hard,  clinkered  portions 
are  therefore  very  valuable  when  ground. 

The  crushing  practice  at  the  Cummings  plant  at  Akron,  N.  Y.,  is 
stated  by  Hies  *  to  include  the  following  processes: 

"At  this  works  a  general  system  of  reduction  is  used,  consisting 
of  (1)  Sturtevant  crushers;  (2)  Cummings  pulverizers;  (3)  ten  run 
of  42-inch  under-runner  millstones  faced  with  chilled-iron  plates;  (4)  ten 
run  of  42-inch  Esopus  under-runner  millstones.  The  material  as  it  is 
conveyed  from  one  to  another  of  these  sets  of  crushers  is  made  to  pass 
over  screens,  whereby  such  material  as  has  been  reduced  to  proper 
fineness  is  separated  from  the  mass  and  is  spouted  to  a  general  con- 
veyor, which  finally  receives  the  product  from  all  the  grinding  machines 
and  conveys  it  to  the  packing-house  "  Each  set  of  crushers,  while  it 
furnishes  a  certain  percentage  of  finished  product,  reduces  the  entire 
material  to  such  a  degree  th'at  what  is  fed  to  the  fourth  series  is  about 
the  size  of  wheat-kernels  and  very  hard  to  reduce.  These  harder- 

*  Ries,  H.     Lime  and  cement  industries  of  New  York.      Bull.  44,  New  York 
State  Museum,  pp.  836,  837. 


MANUFACTURE  OF  NATURAL  CEMENTS.  243 

burned  portions  make  a  cement  which  has  a  much  higher  tensile  strength 
than  the  normally  burned  product. 

Edge-runners. — Dry-pans  are  in  use  at  only  one  natural-cement 
plant,  where  they  take  a  moderately  soft  clinker  from  the  crusher  and 
prepare  it  for  the  tube  mill.  Two  dry-pans  are  in  use,  taking  about 
15  H.P.  each  and  handling  about  400  barrels  each  per  day  of  ten  hours, 
equivalent  to  a  power  requirement  of  about  0.4  H.P.  hour  per  barrel 
of  cement. 

Centrifugal  grinders. — Two  machines  of  this  type,  the  Grffiin  mill 
and  the  Clark  pulverizer,  are  in  limited  use  in  the  natural-cement 
industry. 

The  Clark  anti-friction  pulverizer  has  been  supplied  to  two  of  the 
plants  of  the  Louisville  district  for  use  as  an  intermediate  reducer. 

The  Griffin  mill,  described  with  illustrations  on  pages  440-443,  is,  to 
the  writer's  knowledge,  little  used  in  the  natural-cement  industry. 
The  only  instances  of  its  use  that  have  come  to  his  acquaintance  are  in 
grinding  the  hard  portions  of  the  clinker  produced  at  a  natural-cement 
plant  in  western  New  York  and  as  an  intermediate  reducer  in  one 
of  the  mills  of  the  Louisville  district. 

Ball  grinders. — This  group  includes  three  very  important  and  effi- 
cient machines,  the  kominuter,  the  ball  mill,  and  the  tube  mill.  All 
three  of  these  are  now  in  operation  in  one  important  natural-cement 
district,  and  all  have  proven  satisfactory,  though  in  different  degrees. 
As  these  mills  are  described  in  detail  and  figured  on  pages  447  to  465, 
nothing  need  be  said  here  in  regard  to  their  construction  or  general 
methods  of  operation. 

In  handling  natural-cement  clinker,  certain  things  seem  to  have 
been  firmly  established  by  the  experience  of  the  district  above  alluded 
to.  These  facts  may  be  summarized  as  follows. 

The  tube  mill,  applied  to  the  reduction  of  natural  cement,  is  an 
unqualified  success.  When  working  on  this  material  its  output  is 
very  large,  while  its  repairs  and  wear  of  pebbles  are  trifling.  The 
kominuter,  highly  efficient  in  actual  grinding,  formerly  gave  some  trouble 
in  regard  to  repairs  of  certain  parts,  but  these  defects  have  now  been 
remedied.  The  ball  mill  is  also  efficient  as  regards  output  and  power, 
but  is  much  worse  than  either  kominuter  or  tube  mill  as  regards  repairs. 

Two  Lindhard  kominuters  were  run  for  13}  months  on  a  rather 
hard-burned  natural-cement  clinker,  during  which  time  they  turned 
out  " considerably  over"  400,000  barrels  of  cement.  The  repair 
expenses  for  the  same  period  amounted  to  $300.18,  which  includes 
the  cost  ($182.70)  of  one  extra  set  of  unused  screen  frames. 


244 


CEMENTS,  LIMES,  AND   PLASTERS. 


Two  Davidsen  tube  mills,  running  on  natural-cement  clinker  for 
twenty-six  months,  turned  out  694,522  barrels  of  cement.  During 
this  time  nothing  was  expended  for  repairs.  The  mills  were  only 
dumped  once,  and  the  total  loss  of  screening  pebbles  amounted  to 
less  than  one  barrel.  "The  linings,  silex  and  iron,  and  the  bearings 
were  all  found  in  good  condition,  with  little  or  no  wear  to  speak  of." 


Fig.1 


FIG.  48. — Berthelet  separator. 

1.  Top  view  of  separator  with  covers  removed. 

2.  Side  view  of  separator. 

3.  Cross-section  of  separator. 

4.  Front  elevation  of  separating  system  installed. 

5.  Side  elevation  of  separating  system  installed. 

Another  pair  of  tube  mills  made  a  similar  excellent  record  in  regard  to 
output  and  repairs. 

Impact  pulverizers. — The  Stedman  disintegrator  is  described  and 
figured  on  page  36.  It  is  used  in  at  least  one  natural-cement  plant 
as  a  preliminary  reducer  on  hard,  partly  clinkered  material. 

The  Williams  mill,  which  is  a  high-speed  pulverizer  in  which  revolv- 


MANUFACTURE  OF  NATURAL  CEMENTS. 


245 


ing  hammers  accomplish  the  reduction,  is  described  in  detail  on. 
page  466,  with  illustrations.  It  is  in  use  in  at  least  three  natural-cement 
plants  to  the  writer's  knowledge.  In  two  of  these,  at  Fort  Scott,  Kan., 
it  is  employed  as  a  final  reducer,  taking  a  medium  soft  clinker  from 
pot  crushers  and  reducing  it  to  pass  50-mesh.  In  this  work  it  is  finishing 
50  to  75  barrels  (265  Ibs.  each)  of  cement  per  hour.  At  the  Fembina 


Separating  Tailings  from         y  / 
JEinishing  Stone  Products^)/ / 


''Separating  Coarse  and 
Fine  Tailing 


L_ 

Conveyor  for  Finishing/ 
Stone  Product 


FIG.  49. — Installation  of  Berthelet  separating  system. 


plant  in  North  Dakota  the  Williams  mill  is  used  as  a  preliminary  reducer, 
to  prepare  the  material  for  the  tube  mill.  In  this  work,  which  is  on 
very  hard  clinker,  it  is  handling  about  20  barrels  per  hour. 

Separating  systems. — The  use  of  separators  in  the  grinding  depart- 
ment of  a  natural-cement  plant  greatly  decreases  the  power  consump- 
tion per  ton  of  cement. 

The  objections  to  the  use  of  separators  in  Portland-cement  plants  do 


246 


CEMENTS,  LIMES,  AND  PLASTERS. 


not  hold  with  regard  to  natural-cement  mills,  for  in  grinding  natural 
cement  separation  does  not  destroy  the  homogeneity  of  the  product. 

The  most  effective  separating  system  seen  in  operation  is  the  Berthe- 
let,  first  used  at  the  mills  of  the  Milwaukee  Cement  Company  and  now 
installed  at  many  other  plants.  Sections  of  a  Berthelet  separator  are 
shown  in  Fig.  49,  while  examples  of  installation  of  this  separator  are 
shown  in  both  Figs.  48  and  49.  & 

Power  required  in  grinding. — The  total  horse-power  hours  required 
for  crushing  and  grinding  a  barrel  of  natural  cement  will  depend  on 
(a)  the  hardness  of  burning,  (6)  the  fineness  of  the,  product,  and  (c) 
the  character  of  the  machinery  used. 

In  the  table  below  are  given  the  H.P.  hours  required  to  mill  a  bar- 
rel (280  Ibs.)  of  natural  cement  at  eight  leading  plants.  The  condi- 
tions which  affect  the  power  are  also  briefly  noted. 

TABLE  104. 
POWER  REQUIRED  IN  GRINDING  NATURAL  CEMENT. 


H.P. 

-  ' 

Hours  per 

Mill. 

Barrel 

Burning. 

Product. 

Milling  Machinery. 

(280  Lbs.) 

Cement. 

1 

1.5 

Fairly  hard 

Medium 

Crushers  and  millstones  * 

2 
3 

2.3 

2.7 

Medium 
Very  light 

Fine 
Fine 

Dry-pan  and  tube  mills 
Crackers  and  tube  mills 

4 

2.2 

Medium 

Fine 

Kominuter  f  and  tube  mills 

5 

3.5 

Fairly  hard 

Medium 

Crackers  and  millstones 

6 

2.9 

Medium 

Medium 

Crusher  and  Williams  mill 

7 

5.25 

Very  hard 

Very  fine 

Williams  mill  and  tube  mill 

8 

5.2 

Very  hard 

Fine 

Cracker  and  millstones 

*  Excellent  separating  system, 
t  Not  run  to  full  capacity. 

Fineness  actually  attained.— Until  quite  recently  the  grinding  of 
an  American  natural  cement  was  rarely  carried  further  than  was  neces- 
sary to  pass  95  per  cent  of  the  material  through  a  50-mesh  sieve.  There 
was  no  particular  demand  from  the  engineers  for  a  more  finely  ground 
natural  cement,  and  most  of  the  manufacturers  merely  lived  up  to 
the  requirements  of  the  average  specification.  These  latter  varied 
considerably,  as  may  be  seen  from  the  following  table,  but  in  only  a 
few  cases  was  a  greater  fineness  demanded  than  85  per  cent  through 
a  100-mesh  sieve. 

The  average  requirements,  then,  were  low,  and  the  average  cement 
just  about  passed  the  requirements.  In  some  cases,  however,  a  higher 
standard  was  maintained  by  the  cement  manufacturer  than  by  the 


MANUFACTURE  OF  NATURAL  CEMENTS. 


247 


engineer.  The  "improved"  natural  cements  of  the  Lehigh  district, 
most  of  which  are  made  by  mixing  Portland  and  natural  cement  in. 
various  proportions,  naturally  showed  the  effect  of  the  very  finely  ground 
Portland,  and  at  a  few  other  plants  rather  fine  grinding  was  prac- 
ticed. 

TABLE  105. 
FINENESS  REQUIRED  BY  VARIOUS  SPECIFICATIONS. 


Specification. 

Per  Cent  Required  to  Pass. 

50-mesh. 

100-mesh. 

200-mesh. 

Engineer  Corps,  U.  S.  A.,  1901. 

80 
80 

85 

85 
90 

60 
70 

New  York  State  Canals,  1896.  .  .  . 

90 
95 
96 
99 
99 

Rapid  Transit  Subway,  New  York 
Philadelphia  Dept.  Public  Works, 

if                     ft              e  t               t  ( 

City,  1900-1901  .  .  . 
1893  

1894,  1895  

1893   1897 

The  figures  given  below  represent  the  results  obtained  *  by  very 
careful  sizing  of  three  different  brands  of  natural  cements.  In  making 
these  tests  Mr.  Bleininger  used  sieves  for  the  coarser  sizing  and  a 
washing  method  for  the  finer  work. 

TABLE  106. 
FINENESS  OF  THREE  BRANDS  NATURAL  CEMENT.     (BLEININGER.) 


Diam. 

Diam. 

Diam. 

Total 

Residue 

Residue 

Residue 

between 

between 

between 

Finer 

No. 

Reduced  on 

on 
80-mesh 

on  120- 
mesh 

on  200- 
mesh 

0.008 
and 

0.002 
and 

0.0003 
and 

than 
Last 

than 
200 

Sieve. 

Sieve. 

Sieve. 

0.002 

0.0002 

0.0007 

Size. 

Inch. 

Inch. 

Inch. 

1 

Millstones  

7.36 

9.93 

3.53 

16.42 

13.98 

14.74 

34.04 

20.82 

2 

Tube  mill     . 

10  53 

12  85 

8  50 

11  39 

22  15 

20  72 

13  85 

31  89 

3 

Millstones 

12  50 

11  59 

4  29 

16  52 

21  95 

17  42 

15  76 

28  37 

Within  the  past  few  years  some  natural-cement  manufacturers 
have  realized  that  if  the  natural-cement  industry  is  to  be  maintained 
in  the  face  of  competition  from  Portland  cement  the  product  must 
be  improved.  One  of  the  easiest  methods  of  doing  this  is  to  increase 
the  fineness  of  the  grinding.  This  has  the  effect  of  making  the  cement 
more  sound  and  of  increasing  its  sand-carrying  capacity,  and  therefore 
its  strength  when  tested  as  mortar. 


*  Transactions  American  Ceramic  Society,  vol.  5,  p.  100. 


248  CEMENTS,  LIMES,  AND  PLASTERS. 

Packing  weights. — In  packing  natural  cements  several  different 
standards  of  weight  are  in  existence  in  various  localities.  In  the  Rosen- 
dale,  Howe's  Cave,  and  Akron  districts  the  standard  barrel  weighs 
about  320  Ibs.  gross  or  300  Ibs.  net.  In  the  Lehigh  district  of  Penn- 
sylvania the  gross  and  net  weights  are  usually  300  and  280  Ibs.  respec- 
tively. In  the  Louisville,  Utica,  Milwaukee,  Fort  Scott,  and  other 
western  districts  the  standard  is  a  barrel  weighing  about  285  Ibs.  gross 
or  265  Ibs.  net.  The  recent  specifications  of  the  American  Society  for 
Testing  Materials  require  packing  in  bags  of  94  Ibs.,  three  bags  to  a 
barrel.  K 

Exceptions  to  these  general  rules  occur.  The  Howard  cement  of 
Georgia  is  naturally  so  low  in  specific  gravity  that  an  eastern  natural- 
cement  barrel  will  contain  only  about  240  Ibs.  of  Howard  cement. 
The  Pembina  cement  of  North  Dakota  is,  on  the  other  hand,  packed  at 
the  regular  Portland  weight  of  380  Ibs.  net  per  barrel. 

Costs  of  Manufacture. 

The  items  which  go  to  make  up  the  total  costs  of  natural- cement 
manufacture  are  (a)  cost  of  quarrying  or  mining  the  rock,  (b)  cost  of 
labor  at  kilns  and  mill,  (c)  cost  of  fuel  for  kilns  and  power,  (d)  interest, 
etc.,  on  plant.  Many  of  these  points  have  been  touched  on  in  the  earlier 
portions  of  this  and  the  preceding  chapter,  and  will  only  be  summarized 
briefly  below. 

Cost  of  raw  material. — The  cost  of  excavating  the  raw  material  has 
been  discussed  in  a  preceding  chapter  (pages  219-221).  In  the  follow- 
ing estimates  the  figures  there  given  will  be  taken  as  a  basis  for  cal- 
culation. It  was  stated  that  the  cost  of  raw  material,  delivered  at  the 
kiln,  might  range  from  4  to  13  cents  per  barrel  of  finished  cement. 
For  our  present  purposes  this  range  in  cost  can  be  decreased  some- 
what, for  at  most  plants  the  minimum  and  maximum  limits  may  be 
taken  as  5  and  10  cents  respectively. 

Labor  costs.  —  In  estimating  labor  costs  it  may  be  accepted  for 
the  majority  of  natural-cement  plants  that  the  output  will  vary  between 
5  and  10  barrels  per  day  per  man  employed,  counting  the  men  in  the 
mine  or  quarry  as  well  as  those  in  the  mill.  As  the  cost  of  quarry 
labor  in  the  present  calculation  has  been  already  charged  against  the 
cost  of  raw  material,  the  mill  force  alone  should  be  considered  here. 
Examination  of  a  number  of  plants  proves  that  the  output  varies 
between  12  and  22  barrels  per  day  per  man,  counting  all  men  employed 
around  the  mill  and  kilns,  but  excluding  quarrymen,  miners,  and 
teamsters  engaged  in  hauling  rock  to  the  mill. 


MANUFACTURE  OF  NATURAL  CEMENTS.         249 

Fuel  costs. — It  is  probably  sufficiently  accurate  to  assume  that  in 
the  average  natural-cement  mill  the  consumption  of  fuel  in  the  kilns  may 
range  from  20  to  65  Ibs.  coal  per  barrel  of  cement.  An  additional  8  to 
20  Ibs.  of  coal  will  be  required  to  furnish  power  for  grinding  and  other 
mill  operations.  The  total  coal  consumption  may  therefore  vary  from 
28  to  85  pounds  per  barrel  of  cement.  In  cost  coal  may  easily  vary 
from  $1  to  $4  per  ton,  and  these  figures  have  been  used  as  the  limits 
in  the  calculations  below. 

Total  costs  per  barrel. — Using  the  above  data  as  a  basis,  the  fol- 
lowing estimates  of  the  total  costs  of  manufacture  have  been  prepared. 

TABLE  107. 
ESTIMATES  OF  COST  OF  NATURAL-CEMENT  MANUFACTURE. 

Min.  Max. 

Rock  at  mill $0 .05  $0 . 10 

Labor  at  mill 06  .17 

Coal  for  kilns 02  .12 

Coal  for  power 02  .05 

Interest,  supplies,  etc 03  .06 


Total $0.18  $0.50 

Though  the  minimum  quoted  may  seem  surprisingly  small,  it  is 
very  close  to  the  actual  costs  attained  in  a  prominent  district.  The 
above  costs  do  not,  of  course,  include  the  cost  of  packing  materials, 
though  they  do  include  the  labor  involved  in  packing.  This  distinction 
has  been  made  because  barrels  and  sacks  are  usually  charged  for  at  a 
sufficient  price  to  give  a  small  profit  on  their  use. 

Through  the  courtesy  of  the  manager,  a  typical  daily  cost  report  of  a 
large  American  natural-cement  plant  is  presented  in  Table  108,  below. 
This  mill  averages  500  barrels  of  cement  per  day,  employing  60  men  in 
the  quarry,  kilns,  mill  and  packing-house.  The  output  per  day  averaged, 
therefore,  about  8J  barrels  for  each  man  employed.  If  quarry  labor  be 
excluded,  the  output  per  day  averaged  20  barrels  per  day  for  each  man 
employed  in  kilns,  mill  and  packing-house.  The  rate  of  pay  is,  however, 
higher  than  in  most  mills,  so  that  the  total  labor  costs  are  rather  high.  * 

The  total  cost  of  cement-manufacture  at  this  plant  is  therefore  close  to 
34J  cents  per  barrel.  This  includes  packing  labor,  but  not  cost  of  sacks 
or  barrels,  and  makes  no  allowance  for  interest  charges  or  for  sales  and 
general  superintendence.  Labor  costs,  as  above  noted,  are  high;  and 
the  cement  is  of  low  Cementation  Index,  and  therefore  requires  a  very 
large  amount  of  fuel,  averaging  about  65  Ibs.  of  coal  per  barrel. 


250 


CEMENTS,  LIMES,  AND  PLASTERS. 


TABLE  108. 
DAILY  COST  REPORT  OP  NATURAL-CEMENT  PLANT. 


Cost  per  Day. 

Cost  per  Bbl. 

Quarry.  .  .  . 

{ 

1 
Labor  .  .  .  .  \ 
\ 

I 
Materials  .  .  j 

1  foreman  at  $3.00.  .  .  . 
2  engineers  at  $2.00.  .  . 
2  drillers  at  $2.00  
1  blaster  at  $1  75  .  .  . 

$3.001 
4.00 
4.00 
1.75 
21.00 
26.25  \ 
2.00 
1.50 
5.00 
2.50  | 
0.39J 

$71.39 

$0.143 

12  rockmen  at  $1.75.  .  .  . 
15  strippers  at  $1.75.  .  .  . 
1  blacksmith  at  $2.00.  . 
1  laborer  at  $1.50  
Explosives 

Coal  

Oil  

Kilns. 

( 

Labor  •{ 

1  engineer  at  $2.00.  .  .  . 
2  coalers  at  $2.00,  $1.75. 
1  carman  at  $2  00  

$2.001 
3.75 
2.00 
5.251 
5.00  [ 
36.00  | 
.50 

.isj 

$54.65 

$0  .  109 

Materials  .  .  \ 

3  pitmen  at  $1.75  
3  loaders  at  $1.75,  $1.50 
Coal 

Lights 

Oil  

Mill 

{ 

Labor  ] 

2  engineers  at  $2.00. 
2  millers  at  $2.00,  $2.25. 

$4.001 
4.25 
1.50 
1.50 
5.20 
.501 
.75J 

$17.70 

$0.035 

( 

Materials.  .  j 

1  watchman  at  $1.50.  . 
€oal 

Lights  

Oil  

Packing.  .  < 

c 

Labor            \ 

1  foreman  at  $2.00 
8  spreaders  at  $1.75.  .  . 

$2.00) 
$14.00] 

$16.00 

$0.032 

Total  costs,  excludinj 

y  packages     . 

• 

$172.74 

$0.345 

References  on  manufacturing  methods. — The  papers  and  reports 
cited  below  deal  largely  or  entirely  with  methods  and  details  of  manu- 
facture of  natural  cements.  Incidental  references  of  more  or  less  value 
will  also  be  found  in  the  reports  listed  on  pages  221-222. 

Bleininger,   A.    V.      Manufacture    of  hydraulic   cements.      Bulletin    3,    Ohio 

Geological  Survey.     8vo,  391  pp.     1904. 
Bonnami,  H.     Fabrication  et  controle  des  chaux  hydrauliques  et  des  cimenti. 

8vo,  276  pp.     Paris,  1888. 
Brown,  C.  C.     Directory  of  American  Cement  Industries.     3d  edition,  8vo, 

734  pp.    Indianapolis,  1904. 
Candlot,    E.     Ciments   et    chaux   hydrauliques.      2d    edition,   8vo,   455  pp. 

Paris,  1898. 
Cummings,  U.     American  CementSo     12mo,  299  pp.     Boston,  1898. 


MANUFACTURE  OF  NATURAL  CEMENTS.  251 

Freeman,  H.  C.     The  hydraulic  cement  works  of  the  Utica  Cement  Company. 

Trans.  Amer.  Institute  Mining  Engineers,  vol.  13,  pp.  172-181.     1885. 
Gillmore,  Q.  A.     Practical  Treatise  on  Limes,  Hydraulic  Cements,  and  Mortars. 

8vo,  10th  edition,  334  pp.     New  York,  1890. 
Lewis,  F.  H.     The  natural-cement  plant  at  Speeds,  Ind.     Engineering  Record, 

Sept.  10,  1898.    Reprinted  in  The  Cement  Industry,  pp.  178-183.     1900. 
Lewis,  F.  H.     The  plant  of  the  Lawrence  Cement  Company,  Binnewater,  N.  Y. 

The  Cement  Industry,  pp.  151-160.     1900. 
Lewis,  F.  H.     The  plant  of  the  New  York  and  Rosendale  Cement  Company, 

Rondout,  N.  Y.     The  Cement  Industry,  pp.  161-168.     1900. 
Lewis,  F.  H.     The  plant  of  the  Milwaukee  Cement  Company,  Milwaukee,  Wis, 
-   Engineering- Record,  April  2,  1898.     Reprinted  in  The  Cement  Industry. 

pp.  169-177.     1900. 

Richardson,  C.     Series  of  articles  in  the  Brickbuilder,  1897-1898. 
Siebenthal.     The  Silver  Creek  hydraulic  limestone  of  southeastern  Indiana. 

25th  Ann.  Rep.  Indiana  Dept.  Geology,  pp.  331-389.     1901. 
Anon.     The  Berthelet  separator  and  the  Campbell  kiln  in  cement  manufacture. 

Engineering  News,  Dec.  23,  1897. 


CHAPTER  XIX. 

'  f* 

COMPOSITION  AND  PROPERTIES  OF  NATURAL  CEMENTS. 

THE  preceding  chapters  will  have  failed  of  Hieir  purpose  if  the 
reader  does  not  now  realize  that  the  cements  commonly  grouped  as 
"natural  cements"  differ  so  widely  among  themselves  as  to  almost 
prevent  any  general  statement  being  made  in  regard  to  the  group. 
These  differences  have  appeared  in  the  composition  of  the  various 
cement  rocks,  in  the  degree  of  burning  to  which  they  were  subjected, 
and  in  the  condition  of  the  mass  which  resulted  from  this  burning. 
They  will  appear  still  more  markedly,  however,  in  the  composition 
and  properties  of  the  finished  products. 

In  the  present  chapter  data  will  be  presented  bearing  on  these  sub- 
jects, but  they  will  be  treated  as  illustrating  certain  points  in  connection 
with  the  processes  of  manufacture  rather  than  as  guides  to  the  testing 
or  uses  of  the  cements.  The  chemical  composition  of  the  natural  c.ementa 
will  first  be  taken  up,  after  which  their  physical  properties  will  be  noted. 

Chemical  Composition  of  Natural  Cements. 

A  large  series  of  analyses  of  natural  cements,  both  American  and 
foreign,  are  given  in  the  following  tables.  For  convenience  of  reference 
these  analyses  are  given  by  States  arranged  in  alphabetical  order.  The 
Cementation  Index  has  been  calculated  for  a  number  of  these  products, 
and  is  given  in  the  bottom  line  of  each  table. 

Georgia. — The  two  Georgia  brands  whose  analyses  are  given  in  Table 
112  differ  widely  in  composition  and  index.  The  Howard  cement  is  of 
very  low  index,  much  like  that  from  Akron,  N.  Y.,  and  carries  14  to  20 
per  cent  of  magnesia.  The  Chickamauga  cement  (Dixie  brand)  is,  on 
the  other  brand,  of  medium  high  index,  and  runs  very  low  in  magnesia, 
like  the  natural  cements  of  the  Lehigh  district  and  of  France. 

Illinois. — The  Utica  cements  are  quite  close  in  composition  to  those 
from  the  Rosendale  district;  N.  Y.,  but  run  somewhat  lower  in  index. 

Indiana-Kentucky. — The  Louisville  cements  are  of  moderate  index 
and  average  about  11  per  cent  magnesia. 

252 


COMPOSITION  AND   PROPERTIES  OF  NATURAL  CEMENTS.     253 


TABLE  109. 
ANALYSES  OF  NATURAL  CEMENTS,  GEORGIA. 


1. 

2. 

3. 

Silica  (SiO2)              .    .    . 

22  58 

19  60 

27  68 

Alumina  (A12O3)       .... 

7  23 

}  -,    '««'./ 

9  10 

Iron  oxide  (Fe2O3)   

3  35 

|  11.60  < 

2  52 

Lime  (CaO)  

48  18 

48  86 

57  96 

Magnesia  (MgO)  

15  00 

18  14 

2  52 

Cementation  Index  

1  06 

0  895 

1  44 

1.  "Howard".     Quoted   by  Cummings,   "American   Cements",  p.  35. 

2.  W.  M.  Bouron,  analyst.     Privately  communicated. 

3.  "Dixie".     Guild  &  Co.,  analysts.     Manufacturer's  circular. 


TABLE  110. 
ANALYSES  OF  NATURAL  CEMENTS,  UTICA,  ILLINOIS. 


1. 

2. 

3. 

4. 

5. 

6. 

Silica  (SiO2)  

19.89 

27  60 

34  66 

35  43 

27  00 

29  61 

Alumina  (A12O3)  

11.61 

10.60 

5  10 

f    2  76(?) 

2  34 

Iron  oxide  (Fe2O3).  .  .  . 
Lime  (CaO)  

1.35 
29.51 

0.80 
33.04 

1.00 
30.24 

\  9.92 
33  67 

1    2.16 
29  99 

1.50 
29  74 

Magnesia  (MgO)  
Alkalies  (K2O,Na2O).  . 

20.38 
5.96 

17.26 

7.42 

18.00 
6.16 

20.98 

19.79 
1  77 

20.81 
n  d 

Carbon  dioxide  (CO2).  . 

n.  d. 

1  2.00 

4.84 

15  96(?) 

14  97 

Water     

n.  d. 

J 

Cementation  Index  .  .  . 

1.19 

1.  Haas  &  McGraw,  analysts.     Engineering  News,  April  30,  1896. 

2.  Quoted  by  Cummings,  "American  Cements",  p.  36. 

4.  J.  V.  Blaney,  analyst.     Trans.  Am.  Inst.  Min.  Engrs.,  vol.  13,  PC  180. 

5.  C.  Richardson,  analyst.     Brickbuilder,  vol.  6,  p.  229. 

6.  J.  W.  Skinner,  analyst.     Privately  communicated. 


TABLE  111. 
ANALYSES  OF  NATURAL  CEMENTS,  LOUISVILLE  DISTRICT,  IND.-KY. 


l.* 

2. 

3. 

4. 

5. 

Silica  (SiO2)              

18.92 

21.10 

22.54 

23.29 

24.40 

Alumina  (A1?O3)       

11.02 

I       T     cn/ 

8.24 

5.96 

Iron  oxide  (Fe  O  ) 

1  91 

J       7-5°l 

2.14 

2.16 

6.20 

Lime  (CaO) 

46  90 

44.40 

42.31 

41.28 

41.80 

Magnesia  (MgO) 

0.97f 

7.00 

5.39 

15.39 

16.29 

Alkalies  (K  O  Na06)        .    .  . 

n.  d. 

0.80 

2.82 

1.98 

1.52 

Carbon  dioxide  (CO2)  
Water                      

n.  d. 
n.  d. 

11.18 
1.16 

n.  d. 
n.  d. 

n.  d. 
n.  d. 

}    9.89 

Cementation  Index 

1.23 

*See  next  page  for  references. 

t  Probably  erroneous;    omitted  in  making  up  average. 


254 


CEMENTS,  LIMES,  AND  PLASTERS. 
TABLE  111. — Continued. 


6. 

7. 

8. 

9. 

10. 

Silica  (SiO2)           

25.28 

7.85 
1.43 
.44.65 
9.50 
n.  d. 

1    7.04 

26.40 
6.28 
1.00 
45.22 
r*9.00 
4.00 

7.86 

23.13 

7.87 
1.73 
43.79 
10.43 
2.22 

9.28 
1.28*' 

24.76 
4.78 
3.24 
38.28 
11.94 
n.  d. 

10.39 

24.16 
4.76 
3.40 
46.64 
12.00 

6.75 

Alumina  (Al  CX) 

Iron  oxide  (Fe2Oo) 

Lime  (CaO) 

Magnesia  (MgO)           

Alkalies  (K2O,Na2O)      

Carbon  dioxide  (CO2)  

Water  

Cementation  Index 

1.  Quoted  by  Jameson.     "Portland  Cement",  p.  177. 
2.                      '     Smith.     Mineral  Industry,  vol.  1,  p.  50. 

3.  Haas,  &  McGraw,  analysts.     Engineering  News,  April  30,  1896.      "Diamond"  brand. 

4.  "        "          "  "Star"  brand. 

5.  Lord,  analyst.     Rep.  Ohio  Geological  Survey,  vol.  6,  p.  674. 

6.  Quoted  by  Cummings.     "American  Cements",  p.  35.     "Hulme  Star"  brand. 

7.  "  "Fern  Leaf "  brand. 

8.  Average  of  preceding  seven  analyses. 

).  C.  Richardson,  analyst.     Brickbuilder,  vol.  6,  p.  229. 


Kansas. — The  natural  cements  from  the  Fort  Scott  district  of  Kansas 
are  quite  close  in  magnesia  percentage  and  index  to  those  of  the  Louis- 
ville district,  as  can  be  seen  on  comparing  the  analyses  given  in  tables 
111  and  112. 

TABLE  112. 
ANALYSES  OF  NATURAL  CEMENTS,  FORT  SCOTT,  KAN. 


l. 

2. 

3. 

Silica  (SiO2) 

23  32 

21  80 

21  67 

Alumina  (A12O3) 

6  99 

4  00 

10  85 

Iron  oxide  (Fe2O3)        

5  97 

5  00 

3  05 

Lime  (CaO)         

53  95 

49  80 

49  20 

Magnesia  (MgO)       „  .  ,,  

7  76 

12  16 

7  90 

Carbon  dioxide  (CO2) 

1 

Water 

>        2.00 

4.50 

7.27 

Cementation  Index         

1  19 

1.  Quoted  by  Cummings.     "American   Cements",  p.   35.     "Brockett's  Double  Star 

2.  C.  Richardson,  analyst.     Brickbuilder,  vol.  6,  p.  229. 

3.  "Tests  of  Mstals,  etc.,  at  Watertown  Arsenal",  for  1897,  p.  403. 


brand. 


Maryland. — The  Cumberland  and  Hancock  cements  are  of  partic- 
ularly high  index,  carrying  large  percentages  of  clayey  matter  and  prac- 
tically no  magnesia. 

Minnesota. — Both  brands  of  Minnesota  cements  are  high  in  mag- 
nesia and  of  very  low  index0 


COMPOSITION  AND  PROPERTIES  OF  NATURAL  CEMENTS.      255 


TABLE  113. 

ANALYSES  OF  NATURAL  CEMENTS,  POTOMAC  DISTRICT,  MD. 
(Average  index,  excluding  No.  7,  =  1 . 95.) 


1. 

2. 

3. 

4. 

5. 

Silica  (SiO2) 

25  70 

28  02 

28  30 

28  36 

28  38 

Alumina  (A10O3)      

12  28 

10  20 

10  12 

9  85 

11  71 

Iron  oxide  (Fe2O3)   

4  22 

8  80 

-  4  42 

*3  07 

2  29 

Lime  (CaO)           

52  69 

44  48 

49  60 

45  04 

43  97 

Magnesia  (MgO)     

1.44 

1  00 

3  76 

2  82 

2  21 

Carbon  dioxide  (CO2) 

Water  

Cementation  Index 

1  61 

2  09 

1  70 

1  88 

1  99 

• 

6. 

7. 

8. 

9. 

10. 

Silica  (SiO  ) 

30  02 

36  60 

29  74 

30  22 

29  66 

Alumina  (Al  Oo)                  . 

13  55 

14  58 

8  34 

8  38 

Iron  oxide  (Fe2O2) 

3  00 

5  12 

4  14 

5  38 

}  14.76 

Lime  (CaO)                   . 

~"  44  58 

37  50 

45  66 

39  54 

41  96 

Magnesia  (MgO)           .  . 

2  76 

2  73 

2  86 

3  80 

3  19 

Carbon  dioxide  (CO2)       .    . 

1 

Water  

/  : 



8.13 

10.20 

7.97 

Cementation  Index          . 

2  08 

2  95 

1  92 

2  18 

2  11 

1.  Cumberland,  Md.     A.  W.  Dow,  analyst.     Mineral  Industry,  vol.  6,  p.  96. 

2.  Hancock,  Md.     Quoted  by  Cummings.     "American  Cements",  p.  36. 

3.  Cumberland,  Md.      A.  W.  Dow,  analyst.     Mineral  Industry,  vol.  6,  p.  96. 

4.  Hancock,  Md.  

5.  Cumberland,  Md.     Quoted  by  Cummings.     "American  Cements",  p.  36. 

6.  Hancock,  Md.     A.  W.  Dow,  analyst.     Mineral  Industry ;  voL  6,  p.  96. 

7.  Cumberland,  Md.     A.  W.  Dow,  analyst.     Mineral  Industry,  vol.  6,  p.  96. 

8.  Hancock,  Md.     C.  Richardson,  analyst.     Brickbinlder,  vol.  6,  p.  229. 
9-10.  Cumberland,  Md.     C.  Richardson,  analyst.     Brickbuilder,  vol.  6,  p.  229. 

TABLE  114. 
ANALYSES  OF  MINNESOTA  NATURAL  CEMENTS. 


1. 

2. 

3. 

4. 

5. 

6. 

Silica  (SiO2) 

21  36 

28  43 

16  24 

18  59 

19  02 

27  70 

Alumina  (A12O3) 

3  34 

6  71 

5  35 

9  14 

8  96 

7  06 

Iron  oxide  (Fe2O3) 

3  80 

1  94 

4  71 

1  00 

1  24 

1  86 

Lime  (CaO)                   

45  51 

36  31 

38  53 

40  70 

41  18 

37  00 

Magnesia  (MgO)             

15  02 

23  89 

22  73 

27  00 

26  58 

22  63 

Alkalies  (K2O,Na2O).  
Sulphur  trioxide  (SO8)   

2.03 
1  94 

1.80 
n  d 

2.30 
n.  d 

n.  d. 
n.  d. 

n.  d. 
1  27 

n.  d. 
1.23 

Carbon  dioxide  (CO2)  

/9.26 

/  1.75 

2.46 

Water 

>  10.00 

0.92 

1  0  51 

[3.57 

1  n  d 

n  d 

Cementation  Index 

0  994 

1  2C 

0  792 

0  800 

0  816 

1  26 

1.  Mankato.     C.  Richardson,  analyst.     Brickbuilder,  vol.  6,  p.  229.     1897. 

2.  Quoted  by  Cummings,  "American  Cements",  p.  36. 

3.  C.  F.  Sidener,  analyst,     llth  Ann.  Rep.  Minnesota  Geol.  Survey,  p.  179. 

4.  Austin.     Quoted  by  Cummings,  "  American  Cements  ",  p.  36. 

5.  "  Tests  of  Metals  at  Watertown  Arsenal,  1901. 

6.  Mankato.     "      "       " 


256 


CEMENTS,  LIMES,  AND   PLASTERS. 


New  York. — The  cements  of  the  Rosendale  district  are  the  typical 
American  natural  cements,  with  rather  high  index,  and  carrying  15 
to  20  per  cent  of  magnesia. 

TABLE  115. 
ANALYSES  OF  NATURAL  CEMENTS,  ROSENDALE  DISTRICT,  N.  Y. 


l.* 

2. 

3. 

4. 

5. 

6. 

Silica  (Si02)  
Alumina  (A12O3)       .... 

25.91 
6  20 

27.98 
7  28 

24.30 
7  22 

27.75 
5  50 

30.84 
7.75 

25.92 

Iron  oxide  (Fe2O3)  

3.81 

1.70 

5.06 

4.28 

2.11 

I    9.40 

Lime  (CaO).  ........... 
Maflsrnesia  (MgO)           . 

34.62 
20  92 

37.59 
15  00 

33.70 
20  94 

35.61 
21   18 

34.49 

17  77 

33.18 
19  61 

Alkalies  (K2O,Na2O).  .  .  . 
Sulphur  trioxide  (SO3).  .  . 
Carbon  dioxide  (CO2)  
Water        

n.  d. 
n.  d. 
5.09 
2.80 

7.96 
n.  d. 

}    2.49 

n.  d. 
n.  d. 

/n.  d. 
|n.  d. 

tr. 
0.5 
4.05 
n.  d. 

4.00 
n.  d. 

}    3.04 

n.  d. 
n.  d, 

4.40 

Cementation  Index 

1  29 

1  33 

7. 

8. 

9. 

10. 

11. 

12. 

Silica  (SiO  ) 

30  50 

30  78 

24  42 

22  77 

29  00 

28  91 

Alumina  (A12O«) 

6  84 

J8  16 

/  10  96 

Iron  oxide  (Fe2O3) 

2  42 

|    8.68 

1  3  96 

J  10.43 

10.40 

{    4  68 

Lime  (CaO)           

34  38 

34.14 

36  30 

34  54 

32  35 

34  64 

Magnesia  (MgO)     

18.00 

19.61 

16.93 

21.85 

19  92 

14  82 

Alkalies  (K2O,Na2O).  .  .  . 
Sulphur  trioxide  (SO3).  .  . 
Carbon  dioxide  (CO2).  .  .  . 
Water                 

3.98 
n.  d. 

1    3.78 

1.62 
n.  d. 

3.57 

n.  d. 
n.  d. 
/n.  d. 

In  d 

3.63 
1.44 
2.84 
1  59 

n.  d. 
n.  d. 

n.  d.  1 
n  d  j 

1.80 
1.04 

4.50 

Cementation  Index    .... 

1  74 

13. 

14. 

15. 

16. 

17. 

18. 

Silica  (SiO2) 

29  84 

27  30 

21  73 

17  17 

27  00 

29  98 

Alumina  (A12O3) 

I  15.20 

[7  14 

11  18 

[6  88 

Iron  oxide  (Fe2O3)  
Lime  (CaO)           

35  84 

11.80 
35  98 

4.14 
33.77 

|  10  .  80 
48.28 

17.50 
35.35 

12-50 
33.23 

Magnesia  (MgO)     

14.02 

18.00 

21.20 

19.13 

14.75 

17.80 

Alkalies  (K2O,Na2O)  .... 
Sulphur  trioxide  (SO,).  .  . 
Carbon  dioxide  (CO2).  .  . 
Water  

n.  d. 
0.93 

}    3.73 

6.80 
n.  d. 

2.98 

2.99 
n.  d. 

fn.  d. 

\n.  d. 

tr. 
1.20 
3.38 
n.  d. 

n.  d. 
1.41 

}    4.68 

7.10 
n.  d 

3.13 

Cementation  Index 

1  78 

1  39 

1  19 

*  See  opposite  page  for  references. 


COMPOSITION  AND  PROPERTIES  OF  NATURAL  CEMENTS.     257 
TABLE  115. — Continued. 


19. 

20. 

21. 

22. 

23. 

Silica  (SiO  ) 

31  28 

22  75 

25  00 

28  71 

26  66 

Alumina.  (A12O3) 

1-10* 

/  13  40 

8  93 

5  88 

11  48 

Iron  oxide  (Fe2O3)      

j  il.SO 

(    3  30 

2  27 

3  60 

3  02 

Lime  (CaO)     

36  67 

37  60 

39  30 

27  00 

38  33 

Magnesia  (MgO)  

14  35 

16  65 

16  18 

30  00 

16  41 

Alkalies  (K2O,Na2O)  

n.  d 

n   d 

n  d 

n   d 

n  d 

Sulphur  trioxide  (SO3) 

1  32 

n  d 

1  40 

1  30 

1  35 

Carbon  dioxide  (CO2) 

}       A     nn 

f  5  00 

2  66 

3  52 

2  75 

Water 

\    4.27 

I  1  36 

n  d 

n  d 

n  d. 

Cementation  Index  .  . 

"F.  O.  Norton."     Private  communication. 

Quoted  by  Cummings.     "  American  Cements  ",  p.  35. 

Quoted  by  Lewis.     Mineral  Industry,  vol.  6,  p.  96. 
"Beach's."     J.  O.  Hargrove,  analyst.     Private  communication. 
"Brooklyn  Bridge."     Quoted  by  Cummings.     "American  Cements",  p.  35. 
C.  Richardson,  analyst.     Brickbuilder,  vol.  6,  p.  229. 

Newark  Lime  and  Cement  Co.     Quoted  by  Cummings.     "American  Cements",  p.  35. 
Newark  and  Rosendale.     C.  Richardson,  analyst.     Brickbuilder,  vol.  6,  p.  229. 
"Old  Newark."     Booth,  Garrett,  and  Blair,  analysts.     Mineral  Industry,  vol.  6,  p.  96. 
"Lawrence",  Rosendale  Cement  Co.     Mineral  Resources  U.  S.  for  1883-1884. 
Lawrenceville  cement.     A.  W.  Dow,  analyst.     Mineral  Industry,  vol.  6,  p.  96. 
"Hoffmann'',  Lawrence  Cement  Co.     C.  Richardson,  analyst.     Brickbuilder,  vol.  6,  p.  229. 

"  "  "         "       Quoted  by  Cummings.     "American  Cements",  p.  35. 

"  "  "          "       Haas  and  McGraw,  analysts.     Engineering  News,  April 

30,  1896. 

"Hoffmann",   Lawrence   Cement   Co.     Mineral   Resources  U.   S.   for   1883-1884.     Very  ex- 
ceptional analysis. 

"Rock  Lock."     C.  Richardson,  analyst.     Brickbuilder,  vol.  6,  p.  229. 
Quoted  by  Cummings.     "American  Cements",  p.  35. 

"Hudson  River."  C.  Richardson,  analyst.  Brickbuilder,  vol.  6,  p.  229. 
Rondout,  N.  Y.  L.  C.  Beck,  analyst.  "Mineralogy  of  New  York",  p.  78. 
"  Hoffmann." 

"Newark  and  Rosendale."  } Tests  of  Metals,  etc.,  at  Watertown  Arsenal,  1901. 
"Norton." 


The  following  analysis  is  of  the  natural  cement  made  at  Howe's 
Cave  by  the  Helderberg  Portland  Cement  Company: 

ANALYSIS  OF  NATURAL  CEMENT,  SCHOHARIE  COUNTY,  N.  Y. 

Silica  (SiO2) 26.54 

Alumina  (A12O3) )  c  gg 

Iron  oxide  (Fe2O3) / 

Lime  (CaO) 45.30 

Magnesia  (MgO) 17.06 

Cementation  Index  . .  1.17 


The  cements  of  central  New  York  are  of  low  index,  though  usually 
not  so  low  as  those  of  the  Akron-Buffalo  district. 

The  natural  cements  of  the  Akron-Buffalo  district  carry  usually 
20  to  25  per  cent  magnesia  and  are  of  very  low  index. 


258 


CEMENTS,  LIMES,  AND   PLASTERS, 


TABLE  116. 
ANALYSES  OF  NATURAL  CEMENTS,  CENTRAL  NEW  YORK. 


1. 

2. 

3. 

4. 

Silica  (SiO2) 

20  30 

16  56 

35  43 

24  10 

Alumina  (A12O3)     

I    13.67 

Iron  Oxide  (Fe2O3)  

10.77 

9.92 

11.45 

Lime  (CaO)  

-'47.48 

^    39.50 

33.67 

40.22 

Magnesia  (MgO)                     .    . 

18  55 

22  27 

20.98 

20  60 

Cementation  Index  

1.13 

1.  Brown  Cement  Co.,  Manlius,  Onondaga  County.     W.  M.  Smith,  a/ralyst.     20th  Ann.  Kept* 

U.  S.  Geol.  Survey,  pt.  6,  p.  428. 

2.  Near    Chittenango,    Madison    County.     L.  C.  Beck,    analyst.     "Mineralogy   of   New    York", 

p.  80. 

3.  South  of  Utica,  Oneida  County.     Gillmore.     "Limes,  Cements,  and  Mortars",  p.  125. 

4.  Average  of  preceding  three  analyses. 

TABLE  117. 
ANALYSES  OF  NATURAL  CEMENTS,  AKRON-BUFFALO  DISTRICT,  N.  Y. 


1. 

2. 

3. 

4. 

5. 

Silica  (SiO2)           

17.14 

22  62 

20.20 

22.70 

16.48 

Alumina  (A12O3)  
Iron  oxide  (Fe2O3)  

7.61 
2.00 

7.44 
1.40 

4.40 

2.80 

7.40 

4.40 
2.00 

Lime  (CaO) 

36  83 

40  68 

41  eo 

36  31 

39  20 

Magnesia  (MgO)  
Alkalies  (K2O,Na2O)  
Sulphur  trioxide  (SO3)  
Carbon  dioxide  (CO2)  

25.09 
3.64 
n.  d. 
n.  d. 

22.00 
2.23 
n.  d. 
3.63 

22.24 
1.62 
2.06 

25.72 

n.  d. 
n.  d. 
4.00 

26.52 
1.85 
1.39 

Water 

n  d 

n  d 

}    6-90{ 

n  d 

>    6.80 

Cementation  Index  

0.801 

0.874 

0.871 

0.991 

0.686 

6. 

7. 

8. 

9. 

10. 

Silica  (SiO2)            

26  69 

20  75 

22  94 

20  40 

23  70 

Alumina  (A12O3)  

7  21 

(6  30 

6  22 

16  70 

Iron  oxide  (Fe2O3)  

1  30 

J  10.02 

\2  90 

2  56 

3  30 

Lime  (CaO) 

43  12 

37  54 

43  74 

40  64 

37  00 

Magnesia  (MgO)  
Alkalies  (K2O,Na2O)  
Sulphur  trioxide  (SO3)  
Carbon  dioxide  (CO2)  
Water  

19.55 
1.13 
n.  d. 
1.00 
n.  d. 

26.14 
2.12 
n.  d. 

}    4.58 

20.72 
n.  d. 
n.  d. 
1.00 
n.  d. 

25.80 
n.  d. 
2.91 
1.47 

n  d 

15.30 
n.  d. 
1.98 
2.00 
n  d 

Cementation  Index  

1.18 

0.932 

1.006 

0.856 

2.21 

Average  index,  excluding  No.  10 =      .911 

Average  CaO.  .  ,„ =39.666 

Average  MgO =22 .908 


1.73 


1. 

2. 
3. 
4. 
5. 
€. 

8. 

9. 

10. 


Union  Akron."     Haas  and  McGraw,  analysts.     Engineering  News,  April  30,  1896. 

Newman  Akron."     Quoted  by  Cummings.     "American  Cements",  p.  35. 

Akron  Star."     C.  Richardson,  analyst.     Brickbuilder,  vol.  6,  p.  229.     1897. 

Buffalo  Portland."     N.  Lord,  analyst.     Reports  Ohio  Geological  Survey,  vol.  6,  p.  674. 

'Buffalo."     C.  Richardson,  analyst.     Brickbuilder,  vol.  6,  p.  229.     1897. 

Obelisk."     Quoted  by  Cummings.     "American  Cements",  p.  35. 

C.  Richardson,  analyst.     Brickbuilder,  vol.  6,  p.  229.     1897. 
Storm  King  Portland."     Tests  of  Metals,  etc.,  at  Watertown  Arsenal,  1901,  p. 
Akron  Star."     Tests  of  Metals,  etc.,  at  Watertown  Arsenal,  1901,  p. 
Obelisk."     Tests  of  Metals,  etc.,  at  Watertown  Arsenal,  1901,  p. 


COMPOSITION  AND  PROPERTIES  OF  NATURAL  CEMENTS.     259 


North  Dakota. — The  Pembina  cement  is  a  highly  satisfactory  prod- 
uct, of  high  index  and  low  magnesia,  much  like  the  Chickamauga 
cement  of  Georgia. 

TABLE  118. 
ANALYSES  OF  NATURAL  CEMENT,  NORTH  DAKOTA. 


1. 

2. 

3. 

4. 

Silica  (SiO  ) 

24  62 

23  60 

23  90 

24  72 

Alumina  (A12O.>) 

I    15.12 

Iron  oxide  (I1  e2O3)            

16.50 

15.90 

15.00 

Lime  (CaO)                

52  30 

51  40 

51  40 

51  30 

Cementation  Index  

1  61 

5. 

6. 

.7. 

8. 

Silica  (SiO,)  

24  40 

24  40 

24  06 

24  46 

Alumina  (A12O2)  

Iron  oxide  (Fe2O3)  

I    15.26 

15.38 

15.00 

15.30 

Lime  (CaO)  

52  07 

51.96 

51.96 

52.37 

Cementation  Index 

1  58 

1-8.  Analyses  of  natural  cement,  Pembina  Cement  Co.,  Milton,  N.  D. 

Pennsylvania. — The  Lehigh  district  natural  cements  are  low  in 
magnesia.  As  marketed  they  are  often  very  badly  mixed  products. 
Portland  cement  is  usually  added,  while  adulteration  with  coke  and 
ground  limestone  is  not  unknown. 

TABLE  119. 
ANALYSES  OF  NATURAL  CEMENTS,  LEHIGH  DISTRICT,  PA. 


1. 

2. 

3. 

Silica  (SiO  )                            

18.18 

18.28 

30.40 

10  36 

Iron  oxide  (Fe  O3)      

9.78 

.43    < 

2.60 

Lime  (CaO)               

69.18 

51.53 

52  12 

Magnesia  (MgO)         

1.98 

2.07 

0  21 

Alkalies  (K2O,Na9O)    

n.  d. 

1.50 

n  d. 

Sulphur  trioxide  (SO3)  

n.  d. 

n.  d. 

1.24 

Carbon  dioxide  (CO2)                           

n.  d. 

1                  f 

3.07 

Water                                                 

n.  d. 

}    16.26    < 

n   d. 

1.  Quoted  by  Smith.     Mineral  Industry,  vol.  1,  p.  50. 

2. 

3.  "Bonneville  Improved."     Tests  of  Metals  at  Watertown  Arsenal,  1901. 

West  Virginia- Maryland. — These   cements  are  fairly   low   in   mag- 
nesia and  usually  of  very  high  index. 


260 


CEMENTS,  LIMES,  AND  PLASTERS. 


TABLE  120. 
ANALYSES  OF  NATURAL  CEMENTS,  SHEPHERDSTOWN-ANTIETAM  DISTRICT,  W.  VA.-Mo. 


1. 

2. 

3. 

Silica  (SiO2)                        

33.42 
10.04 
6.00 
*      32.79 
9.59 
0.50 
n.  d. 

}      7.66 
2.35 

36.51 
}      9.36    { 

34.83 
11.33 
1.25 
1.49 

*.  5.13 
2.20 

33.50 
10.44 
3.25 
29.38 
13.37 
n.  d. 
1.15 

7.15 
2.23 

Alumina  (A12O3)     

Lime  (CaO)         '.  i  i 

Magnesia  (MgO)                 

Alkalies  (K  O  Na2O)         

Sulphur  trioxide  (SO3)     

Carbon  dioxide  (CO  ) 

Water 

Cementation  Index                    

1.  Shepherdstown,  W.  Va.     Quoted  by  Cummings.     "American  Cements",  p    35. 
2.  Shepherdstown,  W.  Va.     C.  Richardson,  analyst.     Brickbuilder,  vol.  6,  p.  229. 
3.  Antietam,  Md.     C.  Richardson,  analyst.     Brickbuilder,  vol.  6,  p.  229. 

Wisconsin. — The  Milwaukee  cements  are  of  quite  low  index,  rang- 
ing from  1.10  to  1.20,  and  carry  a  little  more  magnesia  than  do  the 
Rosendale  products. 

TABLE  121. 
ANALYSES  OF  NATURAL  CEMENTS,  MILWAUKEE  DISTRICT,  Wis. 


1. 

2. 

Silica  (SiO)2    

23  16 

25  00 

Alumina  (A12O3)  

6  33 

4  00 

Iron  oxide  (Fe2O3) 

1  71 

2  80 

Lime  (CaO) 

36  08 

33  40 

Magnesia  (MgO) 

20  38 

22  60 

Alkalies  (K2O  Na2O) 

5  27 

2  51 

Sulphur  trioxide  (SO3)  
Carbon  dioxide  (CO2)     .... 

n.  d. 
I      7.07 

2.59 

Water  

9.50 

Cementation  Index  

1.09 

1.17 

1.  Quoted  by  Cummings.     "American  Cements",  p.  35. 

2.  C.  Richardson,  analyst.     Brickbuilder,  vol.  6,  p.  229. 

Belgium. — The  manufacture  and  character  of  the  Belgian  natural 
cements  have  been  described  in  detail  on  preceding  pages.  As  marketed 
they  are  usually  cements  of  low  index  (1.05  to  1.15)  and  carry  small 
percentages  of  magnesia. 

England. — English  natural  cements  are  commonly  products  of  high 
index,  carrying  much  clayey  matter,  and  often  containing  remarkably 
high  percentages  of  iron  oxide. 

France. — The  analyses  given  in  Table  124  represent  a  peculiarly 
homogeneous  group  of  natural  cements,  a  fact  which  is  brought  out 
clearly  when  their  Cementation  Indexes  are  calculated  and  compared. 


COMPOSITION  AND  PROPERTIES  OF  NATURAL  CEMENTS.     261 


TABLE  122. 

ANALYSES  OF  "NATURAL  PORTLAND"  CEMENTS,  BELGIUM. 


1. 

2.  

Silica  (SiO,)          

22  17 

28  0 

Alumina  (A12O3)  

4  60 

3  0 

Iron  oxide  (P'e2O3)  

1  23 

2  0 

Lime  (CaO) 

60  86 

62  0 

Magnesia  (MgO) 

0  73 

0  6 

Sulphur  trioxide  (SO3)  
Carbon  dioxide  (CO2) 

n.  d. 
1  46 

1.2 
1  2 

Water  

0  48 

•n  d 

Cementation  Index    .  .  . 

1  09 

1  32 

1.  Compagnie  Generate  des  Ciments  Portlands  de  1'Escaut,  Tournai. 

2.  Dumon  et  Cie,  Tournai. 

TABLE   123. 
ANALYSES  OF  NATURAL  CEMENTS,  ENGLAND. 


l. 

2. 

3. 

4, 

Silica  (SiO2)  

24.41 

31.36 

26.12 

25  27 

Alumina  (A12O3)  

9.65 

5.01 

7.92 

7  47 

Iron  oxide  (Fe2O.>) 

18  86 

11  74 

6  46 

9  05 

Lime  (CaO) 

41  36 

46  36 

56  44 

55  65 

Magnesia  (MgO) 

4  73 

3  93 

1  60 

1  59 

Cementation  Index        

1  92 

1  48 

1.  Sheppey.   Quoted  by  Redgrave.     "Calcareous  Cements",  p.  49. 

2.  Harwich.         "         " 

3.  Whitby.  "   Zwick,  p.  74. 

4.  London.  "    • 

Germany-Austria. — Analyses  of  a  number  of  German  and  Austrian 
natural  cements  are  given  in  Table  125.  This  series  includes  two  inter- 
esting analyses  (Nos.  5  and  6)  of  cements  of  very  low  index,  carrying 
high  percentages  of  magnesia. 

TABLE  124. 
ANALYSES  OF  NATURAL  CEMENTS,  FRANCE. 


1.* 

2. 

3. 

4. 

Silica  (SiO  ) 

24  94 

20  50 

21  2 

21  82 

Alumina  (Al  Oo) 

9  00 

8  40 

6  9 

8  88 

Iron  oxide  (Fe2O>) 

1  16 

5  70 

13  7 

12  47 

Lime  (CaO) 

63  64 

52  05 

56.6 

55  69 

Magnesia  (MgO)               

1  26 

0.95 

1.1 

1.12 

Sulphur  trioxide  (fc>O3)  

n.  d. 

2.80 

n.  d. 

n.  d. 

Cementation  Indet 

1  22 

1  32 

1  32 

1  39 

*  See  next  page  for  references. 


262 


CEMENTS,  LIMES,  AND   PLASTERS. 
TABLE   124.— Continued. 


5. 

6. 

7. 

8. 

Silica  (SiO2)     

23.50 

24.25 

22.10 

22.61 

Alumina,  (Al  CX)                   .  .  . 

12.50 

10.00 

18.21 

19.79 

Iron  oxide  (I1  62O3)      

3.00 

4.00 

tr. 

tr. 

Lime  (CaO)         

-  52.50 

.      53.50 

55.98 

51.63 

Magnesia  (MsrO) 

'  2  .  50       ; 

*       2  50 

0.37 

0.37 

Sulphur  trioxide  (SO3)           .  . 

1.00 

2.00 

3.34* 

5.60* 

Cementation  Index                . 

1.46 

1.52 

1.45 

1.63 

*  Lime  sulphate,  CaSO4. 

1.  Vassy.     Quoted  by  Cummings.     "American  Cements",  p.  35.     Exceptionally  high-limed. 

2.  "  "         "    Bonnami.     "Chaux  Hydrauliques",  etc.,  p.  54. 

3.  "  "    Zwick.     "Hydraulischer  Kalk  und  Portland-Cement",  p.^ 91. 

5.  Valbonnais.     Slow-setting.     Bonnami.     "Chaux  Hydrauliques",  etc.,  p.( 54. 

6.  ' '  Very  slow. 

7.  Porte  de  France.     Quick-setting.     Bonnami.     "Chaux  Hydrauliques",  etc.,  p.^151. 

8.  "      "        "  Slow -setting. 


TABLE  125. 
ANALYSES  or  NATURAL  CEMENTS,  GERMANY  AND  AUSTRIA. 


1. 

2. 

3. 

4. 

5. 

Silica  (SiO  )              

28.83 

27.88 

24.12 

23.66 

20.80 

Alumina  (A12O3)       

6.40 

6.19 

6.47 

7.24 

5.80 

Iron  oxide  (Fe2O3)  

4.80 

4.64 

5.28 

7.97 

1.50 

Lime  (CaO)     

58.38 

56.45 

59.10 

58.88 

47.83 

Magnesia  (MffO)           

5.00 

4.84 

4.98 

2.25 

24.26 

0.80 

6. 

7. 

8. 

9. 

10. 

Silica  (SiO  )                 

22  14 

25  00 

21  48 

26  80 

23  67 

Alumina  (Al2Oo)         

5  75 

9  00 

6  45 

10  30 

8.83 

Iron  oxide  (Fe2O3)        

3.07 

4  39 

2  80 

1  90 

5.92 

Lime  (CaO)             

44.22 

58  02 

56  73 

59  80 

58  80 

Magnesia  (MgO)       

17.77 

1.08 

3.04 

0.30 

0.73 

Alkalies  (K  O  Na  O) 

4  72 

0  62 

0  70 

1  22 

Cementation  Index              .  .  . 

1.02 

1  39 

1  455 

1  34 

1.  Rudersdorf.  Michaelis,  analyst.     Quoted    in    Wagner's    "Chemical    Technology",  13th   ed., 

p.  669. 

2.  Rudersdorf.  Quoted  by  Cummings.      "American  Cements",  p.  35. 

3.  '     Zwick.      "Hydraulischer  Kalk  und  Portland-Cement",  p.  74. 

4    Hausbergen.  I  Michaelis,  analyst.      Quoted  in  Wagner's  "Chemical  Technology",  13th  ed.r 

5.  Tarnowitz.  p.  669. 

7!  Piesting.  >  Quoted  by  Zwick.     "Hydraulischer  Kalk  und  Portland  -Cement",  p   74. 

8.  Haring.  \ 

10'  PeUrlmoos' 


Quoted  by  Schoch.     "Mortel-Materialen",  p.  74. 


COMPOSITION  AND  PROPERTIES  OF  NATURAL  CEMENTS.       263 


Weight  and  specific  gravity. — The  specific  gravity  of  American 
natural  cements  appears  to  be  greatly  underestimated  by  most  engi- 
neering authorities.  In  a  recent  report,*  for  example,  it  is  stated  that 
"natural  cement  has  a  specific  gravity  of  2.5  to  2.8".  In  reality  very 
few  of  our  American  cements  ever  fall  as  low  in  specific  gravity  as  2.8, 
and  it  would  be  nearer  the  truth  to  say  that,  as  a  class,  the  natural 
cements  range  between  2.8  and  3.2. 

In  the  following   table   (126)   a  number  of  careful  determination 
are  given,  selected  from  various  sources  so  as  to  cover  as  many  cement 
districts  and  brands  as  possible. 

TABLE  126. 
SPECIFIC  GRAVITY  OF  AMERICAN  NATURAL  CEMENTS. 


State.          Locality. 

Brand. 

Authority. 

Specific 
Gravity 

Illinois    Utica    ...... 

? 

C.  Richardson 

2   70 

Kansas    Fort  Scott.  .  . 

9 

<  i           ii 

2.79 

Maryland  Cumberland 

Cumberland  Hydraulic 

Cement  Mfg.  Co. 

Phila.  Cement  Tests, 

1897 

2.90 

«                    tt 

Cumberland  Hydraulic 

' 

Cement  Mfg.  Co. 

ii           (  i           (i 

1899 

2.846 

tt                   it 

Cumberland  and  Poto- 

mac Cement  Co. 

it           it          1  1 

1899 

2.828 

i                     t( 

Potomac 

Watertown  Arsenal, 

1901 

2.94 

1            Round  Top. 

? 

C.  Richardson 

2.84 

t                          i:              (l 

? 

Phila.  Cement  Tests, 

1899 

2.922 

Minnesota  Austin 

Watertown  Arsenal, 

1901 

3.15 

Mankato.   . 

ii                (  < 

1901 

2.93 

(                          e  i 

C.  Richardson 

2  81 

New  York    Rosendale 

? 

1  1           (  ( 

3.04 

t  < 

Hoffmann 

Watertown  Arsenal, 

1901 

3.06 

(C 

Norton 

it                ft 

1901 

3.03 

11 

Newark  and  Rosendale 

it                tt 

1901 

3.06 

Akron.  .  .  . 

"Storm  King  Portland" 

tt                t< 

1901 

3.07 

1  1 

Obelisk 

tt                      tc 

1901     3.12 

1  1 

Star 

Phila.  Cement  Tests, 

1897 

3.17 

Pennsy 
§ 

.vania    Lehigh 

ii 

Co  play  improved 

1897 
1899 

3.00 
2.96 

i 

<  t 

Hercules  improved 

1897 

2.97 

i 

(  t 

American  improved 

1897 

3.07 

t 

K 

(i                  t  ( 

1899 

3.02 

i                     (i 

Bonneville  improved 

Watertown  Arsenal, 

1901 

2.85 

Rapidity  of  set. — Natural  cements  are  normally  much  quicker- 
setting  than  Portlands,  but  this  rapidity  of  set  may  be  changed  by 
aeration,  the  use  of  plaster,  etc.,  to  a  very  remarkable  degree. 

In  1894-95  Sabin  tested  the  effect  of  aeration  on  the  setting  time 
of  natural  cement,  with  the  following  results  :f 

*  Professional  Paper  No.  28,  Corps  of  Engineers,  U.  S.  A.,  p.  11. 
t  Report  Chief  of  Engineers,  U.  S.  A.t  1895,  p.  2937. 


264 


CEMENTS,  LIMES,  AND  PLASTERS. 


TABLE  127. 
EFFECT  OF  AFJRATION  ON  SETTING  TIME  OF  NATURAL  CEMENT. 


(SABIN.) 


No. 

Direct  from  Package. 

After  19  Days'  Aeration. 

Initial  Set, 
Minutes. 

Final  Set, 
Minutes. 

Initial  Set, 
Minutes. 

Final  Set, 
Minutes. 

1    

52 
50 

44 
60 
101 
87 
80 
72 
108 
192 

110-^ 

ioo: 

100 
280 
349 
1200 
1178 
1202      . 
1256 
1247 

54 
51 
48 
100 
147 
130  ' 
122 
125 
202 
234 

173 
164 
166 
326 
306 
1241 
1233 
1227 
1221 
1216 

2    

3  

4                .... 

5           

6  

7  

8  

9  

10-          .. 

Effects  of  gypsum  or  plaster  on  natural  cements. — Natural  cements 
are  affected  by  the  addition  of  gypsum  in  regard  to  setting  time  and 
strength  in  much  the  same  manner  as  Portland  cement  would  be. 
The  degree  to  which  these  effects  are  produced,  for  the  same  per- 
centage of  gypsum,  depends  entirely  upon  the  chemical  composition 
of  the  respective  cements.  This  fact  seems  to  have  been  entirely  over- 
looked by  experimenters,  and  in  consequence  the  tests  which  have  been 
made  are  deprived  of  much  of  their  value,  because  the  analysis  of  the 
cement  is  rarely  included  in  the  report  of  the  test. 

Experiments  on  the  effect  of  gypsum  on  the  rate  of  set  have  been 
carried  out  by  Sabin,*  and  the  results  are  embodied  in  Table  128,  below, 
and  are  shown  diagrammatically  in  Fig.  50. 

TABLE  128. 
EFFECT  OF  PLASTER  ON  SETTING  TIME  OF  NATURAL  CEMENT.     (SABIN.) 


Brand. 

Per  Cent 
Plaster. 

Setting  Time. 

Initial, 
Minutes. 

Final, 
Minutes. 

A 

0 
1 
2 
3 

6 
0 
1 
2 
3 
6 

38 
106 
107 
86 
42 
93 
179 
302 
295 
93 

543 
414 
527 
671 
632 
193 
439 
592 
725 
698 

B  .. 

n 

Report  Chief  of  Engineers,  U.  S.  A.,  1895,  p.  2938. 


COMPOSITION  AND  PROPERTIES  OF  NATURAL  CEMENTS.     265 

From  this  table  it  will  be  seen  that  the  maximum  retardation  of 
the  initial  set  took  place  with  both  brands  when  2  per  cent  of  plaster 
was  used.  The  final  set,  however,  experienced  its  greatest  retardation 
in  both  cases  when  3  per  cent  of  plaster  was  employed. 


FIG.  50.' 


0  5  10 

PERCENTAGE  OF  PLASTER  PARIS 

-Effect  of  blaster  on  setting  time.       (Sabin.) 


Sabin  also  tested  t  the  effects  of  plaster  on  the  tensile  strength 
of  both  neat  and  mortar  briquettes.  The  results  of  these  tests  are 
shown  in  the  following  table  (129) : 

TABLE  129. 
EFFECT  OF  PLASTER  ON  TENSILE  STRENGTH  OF  NATURAL  CEMENT.     (SABIN.) 


Composition. 

Tensile  Strength,  Pounds. 

Per  Cent 

Cement. 

Sand. 

Plaster. 

7  Days. 

6  Months. 

1  Year. 

1 

0 

0 

146 

383 

1 

0 

1 

156 

398  x 

1 

0 

2 

115  1 

323 

1 

0 

3 

312  2 

1 

0 

6 

234  3 

1 

2 

0 

62 

374 

448 

1 

2 

1 

80 

312 

395 

1 

2 

2 

94 

355 

408 

1 

2 

3 

86     *r 

131  3 

1 

2 

6 

... 

151  3 

107  3 

1  Surf  ace  cracks.          2  Swelled  and  nearly  disintegrated.  8  Badly  cracked  and  swelled. 


*  From  Johnson's  "Materials  of  Construction  ",  p.  187. 
t  Report  Chief  of  Engineers,  U.  S.  A.,  1896,  p.  2857. 


266 


CEMENTS,  LIMES,  AND    PLASTERS. 


These  tests  would  appear  to  show  that  the  addition  of  even  1  per 
cent  of  plaster  has  injurious  effects  on  the  soundness  of  the  cement, 
and  less  markedly  on  its  tensile  strength.  Unfortunately,  the  analysis 
of  the  cement  tested  is  not  given,  and  even  its  name  is  suppressed,  so 
that  the  results  are  less  instructive  than  they  might  have  been. 


1000 


FIG.  51.* — Effect  of  salt  on  compressive  strength.     (Tetmajer.) 


I         I        I 

HARDENED  IN  AIR 
HARDENED  IN  WATER 


21         28          35         42         49          56          62          70          77         84 


FIG.  52.* — Effect  of  salt  on  tensile  strength.     (Tetmajer.) 

In  general  it  may  be  said  that  the  effects  of  gypsum  or  plaster  will 
be  directly  proportional  to  the  percentage  of  alumina  contained  in 
the  cement.  This  statement  has  never  before  been  explicitly  made, 


*  From  Johnson's  "Materials  of  Construction",  p.  621. 


COMPOSITION  AND  PROPERTIES  OF  NATURAL  CEMENTS.     267 

but  it  is  a  necessary  corollary  from  recent  studies  on  the  behavior  of 
cements  with  gypsum  and  in  sea-water. 

Effect  of  salt  on  strength. — In  laying  masonry  in  freezing  weather 
it  has  been  customary  to  specify  the  use  of  salt  in  the  water  used  for 
the  mortar.  This  lowers  the  freezing  temperature  of  the  water,  but 
does  not  seem  to  be  of  any  particular  benefit  in  other  respects.  It 
decreases  quite  markedly  the  tensile  and  compressive  strength  of  the 
mortars,  even  when  only  a  small  percentage  of  salt  is  added. 


SSES   * 


SIEVE 


FIG.  53. 


4  6  8 

PERCENTAGE  OF  SALT  IN   WATER 

—Effect  of  salt  on  tensile  strength. 


10 


12* 


The  effect  of  salt  on  the  strength  of  natural-cement  mortars  is  shown 
in  Figs.  51 ,  52,  and  53.  Of  these  Tetmajer's  experiments  were  made 
on  European  natural-cement  mortars,  mixed  1  cement  to  3  sand  and 
tested  at  various  ages.  Those  shown  in  Fig.  52  were  made  on  Louis- 
ville and  Portland-cement  mortars  and  all  tested  at  six  months. 

Tensile  strength. — In  tensile  strength  the  average  natural  cement 
ranks  considerably  lower  than  the  average  Portland.  This  is  particu- 
larly noticeable  when  the  cements  are  tested  with  sand. 

This  general  rule  as  to  the  relative  strength  of  natural  and  Port- 
land cements  is  well  known,  but  the  exceptions  to  the  rule  are  not  fre- 
quently discussed.  It  is  a  fact,  however,  that  certain  brands  of  natu- 
ral cements  are  about  as  strong,  either  neat  or  with  sand,  as  the  aver- 
age imported  Portland,  and  there  is  no  reason  why  a  number  of  natural 
cements  could  not  be  carried  up  to  this  grade.  The  average  results 
of  extensive  series  of  tests  on  various  natural  cements  are  given  dia- 
grammatically  in  Figs.  54,  55,  56,  57,  58,  59,  and  60. 

In  Fig.  55  are  shown  the  results  of  a  very  large  number  of  tensile 


*  From  Johnson's  "Materials  of  Construction",  p.  618. 


268 


CEMENTS,  LIMES,  AND  PLASTERS. 


TOO 


FIG.  54.* — Tensile  strength  of  Louisville  cement,  St.  Louis  Waterworks,  1896. 


FIG.  55. — Tensile  strength  of  Lehigh  district  natural  cements. 
(Philadelphia  tests,  1893,  1894,  1895,  1896.) 

*  From  Johnson's  "Materials  of  Construction",  p.  570. 


COMPOSITION  AND  PROPERTIES  OF  NATURAL  CEMENTS.     269 

tests,  at  various  ages  up  to  3  years,  on  the  "improved"  natural  cements 
of  the  Lehigh  district  of  Pennsylvania. 

The  results  of  a  number  of  tests  of  natural  cements  from  the 
Cumberland-Hancock  district  of  Maryland  have  been  averaged  and  are 
shown  diagramatically  in  Fig.  56. 


400 


300 


200 


1 


100 


\ 


ISeaL— 


I,  BL. 
11  f   1 


w  t~     c<i 


BB}'<B4*l<S 

I  I  I   I   1  1 

1   I:  §1    §   § 

aaaasa 

eo        'S'        10        so        »>       oo 


I .  I  I  J  i  "1 


§   I   I   § 

aaaa 


aaa 


FIG.  56.  —  Tensile  strength  of  Cumberland  natural  cements. 
(Philadelphia  tests,  1894,  1895,  1896.) 


Tests  of  natural  cements  from  Akron,  N.  Y.,  and  Cumberland,  Md., 
during  1897  and  1S98,  are  shown  diagrammatically  in  Fig.  57.  These 
tests  cover  ages  of  1  day  to  6  months. 


270  CEMENTS,  LIMES,  AND  PLASTERS. 

500 1 


FIG.  57. — Tensile  strength  of  Akron  and  Cumberland  cements. 
(Philadelphia  tests,  1897,  1898.) 


COMPOSITION  AND   PROPERTIES  OF  NATURAL  CEMENTS.     271 


300 


200 


ioo 


.   0 
300 


200 


2  100 


400 


200 


100 


7 


MILWAUKEE  CEMENT 
86.4/c  PASSED  NO.  50  SIEVE 


U' 

78.6  <fcP 


68.0^ 


1:2 


ICA  CEMENT 
iSSED  NO.  50  SIEVE 


LOUISVILLE  CEMENT 
88.6$  PASSED  NO.  50  SIE 


73.3  f, 


"  "  r 


0         1         2         3         4         56         7          8  \  .    9         10       11        13 
AGE  IN  MONTHS 

FIG.  58.* — Tensile  strength  of  natural  cements,  Cairo  Bridge  tests. 


*  From  Johnson's  "Materials  of  Construction  ",  p.  569. 


272 


CEMENTS,  LIMES,  AND  PLASTERS. 


0  10  20  30  40  50 

AGE  fN  WEEKS 

FIG.  59.* — Tensile  strength  Rosendale  cements,  Boston  Main  Drainage,  1885. 


500 


400 


200 


100 


.-- -o- 


50 


100 


250 


300 


350 


150       200 
AGE  IN  DAJS 

FIG.  60.  t — Tensile  strength  natural  cements,  Sault  Ste.  Marie,  1894. 

The  effect  on  the  tensile  strength  of  varying  the  proportion  of 
sand  is  well  shown  in  the  tests  made  by  Sabin  J  and  summarized  in 
Table  130.  These  tests  are  shown  diagrammatically  in  Fig.  61. 

*  From  Johnson's  ''Materials  of  Construction",  p.  568. 

t  Ibid.,  p.  570. 

%  Report  Chief  of  Engineers,  U.  S.  A.,  1895,  p.  2982. 


COMPOSITION  AND  PROPERTIES  OF/NATURAL  CEMENTS.     273 


TABLE  130. 
EFFECT  OF  SAND  ON  TENSILE  STRENGTH  OF  NATURAL  CEMENT.     (SABIN.) 


Composition. 

Tensile  Strength. 

Cement. 

Sand. 

Maximum. 

Minimum. 

Average. 

1 

0 

428 

340 

380 

1 

1 

332 

251 

297 

1 

2 

298 

224 

260 

1 

3 

208 

144 

183 

1 

4 

154 

74 

128 

1 

5 

109 

61 

81 

1 

6 

81 

56 

69 

1 

7 

68 

32 

56 

1 

8 

66 

29 

53 

Neat  Cement 


1  Cement:  1  Sand. 


1  Cement:  2  Sand. 


1  Cement:  3  Sand. 


1  Cement:  4  Sand. 


1  Cement:  5  Sand. 


1  Cemente  6  Sand. 


1  Cement:  7  Sand. 


1  Cement:  8  Sand 


Tensile  strength  Ibs.  per  sq.  in. 


8 


FIG.  61. — Effect  of  sand  on  tensile  strength  of  natural  cement.     (Sabin/ 


274 


CEMENTS,  LIMES,  AND  PLASTERS. 


123456 

AGE    IN    MONTHS 

FIG.  62.* — Tensile  tests,  Sault  Ste.  Marie. 

• 

Compressive    strength. — Tests  on  various  natural   cements  carried 
out  by  Clifford  Richardson  f  are  summarized  in  Table  131. 

TABLE  131. 
COMPRESSIVE  TESTS  OF  NATURAL  CEMENTS.     (RICHARDSON.)   . 


f:       f._^  .:.-.,.-. 

Neat  Cement. 

1  Cement,  2  SancL 

7  Days. 

28  Days. 

3  Months. 

7  Days. 

28  Days. 

3  Months. 

2718 

Buffalo  N  Y 

997 
1325 
1737 
913 
769 
1072 
1663 
1538 

1300 
2812 
2795 
1457 
1256 
2402 
2288 
1972 
1737 

3is5 

700 
700 
500 
506 
417 
988 
575 
1075 

980 
1300 
1065 
822 
680 
1470 
834 
1450 
614 

Akron  Star  N  Y    . 

Louisville,  Ky       

Milwaukee,  Wis  

Fort  Scott,  Kan  

(  <            (  (             (  e 

Mankato,  Minn.  
Utica,  111     

Rosendale,  N.  Y  

Average  

1252 

2002 

3155 

683 

1024 

2718 

The  following  tests  (Table  132)  of  compressive  strength  were  made  on 
4-inch  cubes  at  the  Watertown  Arsenal. 


*  From  Johnson's  "Materials  of  Construction",  p.  571. 

t  Brickbuilder,  vol.  6,  p.  253. 

.£  Report  on  tests  of  metals,  etc.,  at  Watertown  Arsenal  for  1902,  pp.  377-381. 


COMPOSITION  AND   PROPERTIES  OF  NATURAL  CEMENTS..    275 


TABLE  132. 

COMPRESSIVE  STRENGTH  OF  4-iNCH  NATURAL-CEMENT  CUBES. 
(WATERTOWN  ARSENAL.) 


Brand. 

Per   Cent 
Water. 

Compressive  Strength,  Lbs.  per  Square  Inch, 

7  Days. 

1  Month. 

3  Months. 

12  Months. 

35.4 

41.2 
39.2 
35.8 
39.6 

38.7 
36.2 

38.7 

356 
566 
423 
750 
472 

407 
464 
620 

1090 
1020 
840 
1360 
880 

1090 
790 
1130 

1530 
1420 
1110 
2220 
1570 

1440 
1230 
1560 

1100 
1590 

Potomac    Md 

Obelisk,  Erie  County,  N.  Y  
Norton,  Ulster  County,  N.  Y  
Newark     and     Rosendale,     Ulster 
County,  NY     

Hoffman           

Bonneville  improved,  Penna  

TABLE  133. 
EFFECT  OF  HEATING  ON  COMPRESSIVE  STRENGTH.     (WATERTOWN  ARSENAL.) 


Com- 

Brand. 

Mixture. 

Per  Cent 
Water. 

Age. 
Yrs.  Mon.  Days 

Heated  to 

pressive 
Strength, 

Lbs.  per 
Sq.  In. 

Mankato. 

Neat  cement 

38 

1     2     19 

Not  heated 

1867  • 

a 

ii          (  t 

38 

1     2     19 

200°  F. 

1657 

(i 

n          n 

38 

1     2     19 

300°  F. 

1877 

t( 

((          n 

38 

1     2     19 

400°  F. 

1967 

tt 

({          <( 

48 

2     19 

500°  F. 

1603 

(t          it 

48 

2     19 

600°  F. 

1453 

(i          fi 

48 

2     19 

700°  F. 

1497 

ti          ft 

48 

2     19 

800°  F. 

1400 

a          a 

48 

2     19 

900°  F. 

1185 

1  cement,  1  sand 

28 

6     21 

Not  heated 

538 

1       '          1 

31 

6     21 

200°  F. 

491 

1       '          1 

31 

6     21 

300°  F. 

433 

1       '          1 

28 

6     21 

500°  F. 

471 

1       '          1 

28 

6     21 

700°  F. 

381 

(( 

1       '          1 

31 

6     21 

900°  F. 

317 

tt 

1    .   '          1  , 

31 

1     6     21 

500°  F. 

329 

Ratio  of  compressive  to  tensile  strength. — The  ratio  between  the 
compressive  and  tensile  strength  is  apparently,  in  the  natural  cements, 
considerably  lower  than  in  Portland  cement. 


,276 


CEMENTS,  LIMES,  AND  PLASTERS. 


TABLE  134. 
RELATION  OF  TENSILE  TO  COMPRESSIVE  STRENGTH  OF  NATURAL  CEMENT. 


(SABIN.) 


Brand, 

.  Composition. 

Age. 

Average 
Tensile 
Strength, 
Pounds  per 
Square  Inch. 

Average 
Compressive 
Strength, 
Pounds  per 
Square  Inch. 

Ratio 
Compressive 
-J-  Tensile. 

A 

1  cement,  2  sand 

1  28  days^ 

116 

662 

5.71 

B  

1                 2 

28     "  ' 

187 

1020 

5.45 

C  
D    

1                 2 
1                 2 

28     ' 
28     ' 

237 
117 

1175 
550 

4.96 
4.70 

E  

2 

28     ' 

286 

1224 

4.28 

A  

2 

3  months 

334 

'•   1261 

3.77 

B    .... 

"        2 

3 

294 

1118 

3.80 

c 

"        2 

3        ' 

370 

1698 

4.59 

D      

"        2 

3  •  .  ' 

298 

1076 

3.61 

E  

"        2 

3        ' 

291 

1018 

3.50 

Report  Chief  of  Engineers,  U.  S.  A.,  1896,  p.  2872. 

The  following  tests  were  made  by  Prof.  Creighton  on  samples  of 
the  Utica  (111.)  natural  cement  used  in  the  construction  of  the  drain- 
age works  at  New  Orleans. 

TABLE  135. 

RELATION  OF  TENSILE  TO  COMPRESSIVE  STRENGTH  OF  UTICA  NATURAL  CEMENT. 

(CREIGHTON.) 


Composition. 

Age. 

Average 
Tensile, 
Pounds  per 
Square  Inch. 

Average 
Compressive, 
Pounds  per 
Square  Inch. 

Ratio 
Compressive 
-^  Tensile. 

Neat 

1  cer 
1 
1 
1 
1 
1 
1 
1 
1 
1 
1 
1 
1 
1 
1 
1 
1 
1 

cement  

7  days 
14     " 
28     " 
2  months 
3       " 
6       " 
7  days 

28     " 
2  months 
3       " 
6       " 
7  days 
14     " 
28     " 
2  months 
3       " 
6       " 
7  days 
14     " 
28     " 
2  months 
3       " 
6       " 

210 
255 
270 
283 
300 
340 
136 
269 
290 
302 

313 
76 
114 
162 
164 
172 
176 

98 
112 
124 
131 
138 

1300 
1705 

1805 

1170 
1417 
1583 
1723 
1940 

568 
655 
840 
1135 
1768 

352 
403 

456 
923 

5.09 
6.32 

5.31 

4.35 
4.88 
5.24 

6.19 

4.98 
4.05 
5.12 
6.60 
10.05 

3.59 
3.59 

3.48 
6.68 

nent,  1  sand  
1       '     

"        1       ' 

1       '     
"        1       '       .    . 

"        1      * 

"        2       '    

u        2      ( 

"        2       ' 

11                O             ( 

«           9         ( 

(i        2     " 

t(            o       « 
o               

"        3    "    

«           o      « 
o              .  .  .  .  . 

ft                   0           (I 

"       3    "    ! 

"       3    "    

COMPOSITION  AND  PROPERTIES  OF  NATURAL  CEMENTS.      277 


Modulus  of  elasticity. — Tests  of  the  modulus  of  elasticity  of  several 
American  natural  cements  made  at  Watertown  Arsenal*  are  sum- 
marized in  Table  136. 

TABLE  136. 
MODULUS  OF  ELASTICITY. 


Ultimate 

Brand. 

Com- 
position. 

Weight 
per 
Cu.  Ft. 

Age. 
Mo.  Da. 

Strength, 
Pounds 
per 

E. 

Sq.  In. 

Lbs.  sq.  in. 

Austin  

Neat 

100  6 

2      14 

610 

.#(100-500)     =    567,000 

Newark  &  Rosendale. 

<  < 

99.5 

2     15 

700 

£(100-500)      -    485,000 

ii       «          n 

« 

120 

1 

£(100-500)      =    988,000 

it       it         tt 

It 

120 

5 

2720 

£(100-1000)    =1,818,000 
£(1000-2000)  =  1,342,000 

Obelisk.  

tt 

107.0 

2      8 

1430 

£(100-500)     =    976,000 

£(500-1000)    =    826,000 

<  < 

It 

116.6 

2      7 

1900 

£(100-1000)    =1,132,000 

-I 

1  cement 

}  121.9 

2       5 

1330 

£(100-1000)    =1,146,000 

I 

1  sand 

*  Report  of  tests  of  metals,  etc.,  made  at  Watertown  Arsenal,  for  1902,  pp.  501- 


505. 


CHAPTER  XX. 
SPECIFICATIONS  FOR  NATURAL  CEMENTS. 

SEVERAL  sets  of  specifications  for  natural  cerrients  are  reprinted 
below,  with  a  final  comparative  summary  of  their  requirements  on 
different '  points. 

New  York  State  Canals,  1896. 

Natural  hydraulic  cement  must  be  of  the  best  quality  and  of  such 
fineness  that  90  per  cent  will  pass  through  a  sieve  of  2500  meshes  per 
square  inch  and  80  per  cent  through  a  sieve  of  10,000  meshes  per  square 
inch. 

Briquettes  made  of  equal  parts  of  natural  hydraulic  cement  and 
crushed  quartz,  immersed  in  water  as  soon  as  they  are  sufficiently  hard 
to  sustain  a  •g'j-inch  wire  weighted  with  1  lb.,  must  show  a  tensile 
strength  of  65  Ibs.  per  square  inch  at  the  expiration  of  seven  days, 
but  briquettes  showing  less  than  such  strength  will  be  held  until 
twenty-eight  days  have  elapsed,  when,  if  they  then  show  such  strength 
as  to  sustain  as  many  pounds  per  square  inch  above  125  as  the  seven- 
day  test  shows  them  to  have  fallen  below  65  they  will  be  deemed 
to  have  passed  this  test.  Briquettes  made  of  neat  cement  must  not 
set  so  as  to  .support  a  TV-mch  wire  with  a  load  of  one  quarter  of  a  pound 
in  less  than  five  minutes.  Briquettes  of  neat  cement  must  not  show 
checks  or  cracks  when  immersed  in  water  for  seven  days  after  mixing. 

Rapid  Transit  Subway,  New  York  City,  1900-1901. 

Fineness. — 95  per  cent  shall  pass  a  No.  50  sieve  and  85  per  cent 
a  No.  100  sieve. 

Tensile  strength. — At  the  end  of  seven  days,  one  day  in  air,  six 
days  in  water,  125  lbs.;  neat.  At  the  end  of  twenty-eight  days,  one 
day  in  air,  twenty-seven  days  in  water,  200  Ibs.,  neat.  When  mixed 
1  to  1  with  quartz  sand:  at  the  end  of  seven  days,  one  day  in  air,  six 
days  in  water,  100  Ibs.;  at  the  end  of  twenty-eight  days,  one  day  in 
air,  twenty-seven  days  in  water ,  150  Ibs. 

278 


SPECIFICATIONS  FOR  NATURAL  CEMENTS.  279 

Soundness. — Tests  for  checking  and  cracking  and  for  color  will  be 
made  by  molding,  on  plates  of  glass,  cakes  of  neat  cement  about  3  inches 
in  diameter,  J  inch  thick  in  the  center,  and  with  very  thin  edges.  One 
of  these  cakes  when  set  perfectly  hard  shall  be  put  in  water  and  examined 
for  distortion  or  cracks,  and  one  shall  be  kept  in  air  and  examined 
for  color,  distortion,  and  cracks. 

Engineer  Corps,  U.  S.  Army,  1901 

(1)  The  cement  shall  be  a  freshly  packed  natural  or  Rosendale, 
dry,  and  free  from  lumps.     By  natural  cement  is  meant  one  made  by 
calcining  natural  rock  at  a  heat  below  incipient  fusion  and  grinding 
the  product  to  powder. 

(2)  The  cement  shall  be  put  up  in  strong,  sound  barrels,  well  lined 
with  paper  so  as  to  be  reasonably  protected  against  moisture,  or  in 
stout  cloth  or  canvas  sacks.     Each  package  shall  be  plainly  labeled 
with  the  name  of  the  brand  and  of  the  manufacturer.     Any  package 
broken  or  containing  damaged  cement  may  be  rejected,  or  accepted 
as  a  fractional  package,  at  the  option  of  the  United  States  agent  in 
local  charge. 

(3)  Bidders  will  state  the  brand  of  the  cement  which  they  propose 
to  furnish.     The  right  is  reserved  to  reject  a  tender  for  any  brand  which 
has  not  given  satisfaction  in  use  under  climatic  or  other  conditions  of 
exposure  of  at  least  equal  severity  to  those  of  the  work  proposed. 

(4)  Tenders   will   be    received    only   from   manufacturers    or   their 
authorized  agents. 

(The  following  paragraph  will  be  substituted  for  paragraphs  3  and  4 
above  when  cement  is  to  be  furnished  and  placed  by  the  contractor: 

No  cement  will  be  allowed  to  be  used  except  established  brands 
of  high-grade  natural  cement  which  have  been  in  successful  use  under 
similar  climatic  conditions  to  those  of  the  proposed  wbrk.) 

(5)  The  average  net  weight  per  barrel  shall  not  be  less  than  300  Ibs. 
(west  of    the  Allegheny  Mountains  this  may  be  265  Ibs.)   .  .  .  sacks 
of  cement  shall  have  the  same  weight  as  1  barrel.     If  the  average  net 
weight,  as  determined  by  test  weighings,  is  found  to  be  below  300  Ibs. 
(265  Ibs.)  per  barrel,  the  cement  may  be  rejected,  or,  at  the  option 
of  the  engineer  officer  in  charge,  the  contractor  may  be  required  to 
supply  free  of  cost  to  the  United  States  an  additional  amount  of  cement 
equal  to  the  shortage. 

(6)  Tests  may  be  made  of  the  fineness,  time  of  setting,  and  tensile 
strength  of  the  cement. 


280  CEMENTS,  LIMES,  AND   PLASTERS. 

(7)  Fineness. — At  least  80  per  cent  of  the  cement  must  pass  through 
a  sieve  made  of  No.  40  wire,  Stubb's  gauge,  having  10,000  openings 
per  square  inch. 

(8)  Time  of  Setting. — The  cement  shall  not  acquire  its  initial  set 
in  less  than  twenty  minutes  and  must  have  acquired  its  final  set  in  four 
hours. 

(9)  The  time  of  setting  is  to  be  determined  from  a  pat  of  neat 
cement  mixed  for  five  minutes  with  30  per  cent  of  water  by  weight 
and  kept  under  a  wet  cloth  until  finally  set.     The  cement  is  considered 
to  have  acquired  its  initial  set  when  the  pat  will  be*ar,  without  being 
appreciably   indented,    a   wire   T1^   inch  in   diameter   loaded   to   weigh 
J  Ib.    The  final  set  has  been  acquired  when  the  pat  will  bear,  without 
being  appreciably  indented,  a  wire  -£%  inch  in  diameter  loaded  to  weigh 
1  Ib. 

(10)  Tensile   strength. — Briquettes    made    of    neat    cement    shall 
develop  the  following  tensile  strengths  per  square  inch,  after  having 
been  kept  in  air  for  twenty-four  hours  under  a  wet  cloth  and  the  balance 
of  the  time  in  water: 

At  the  end  of  seven  days,  90  Ibs.;  at  the  end  of  twenty-eight  days, 
200  Ibs. 

Briquettes  made  of  one  part  cement  and  one  part  standard  sand 
by  weight  shall  develop  the  following  tensile  strengths  per  square  inch: 

After  seven  days,  60  Ibs.;   after  twenty-eight  days,  150  Ibs. 

(11)  The  highest  result  from  each  set  of  briquettes  made  at  any 
one  time  is  to  be  considered  the  governing  test.     Any  cement  not  show- 
ing an  increase  of  strength  in  the  twenty-eight-day  tests  over  the  seven- 
day  tests  will  be  rejected. 

(12)  The  neat  cement  for  briquettes  shall  be  mixed  with  30  per 
cent  of  water  by  weight,  and  the  sand  and  cement  with  17  per  cent 
of  water  by  weight.     After  being  thoroughly  mixed  and  worked  for 
five  minutes  the  cement  or  mortar  is  to  be  placed  in  the  briquette  mold 
in  four  equal  layers,  each  of  which  is  to  be  rammed  and  compressed 
by  thirty  blows  of  a  soft  brass  or  copper  rammer  three  quarters  of  an 
inch  in  diameter  (or  seven  tenths  of  an  inch  square  with  rounded  cor- 
ners), weighing  1  Ib.     It  is  to  be  allowed  to  drop  on  the  mixture  from 
a  height  of  about  half  an  inch.     Upon  the  completion  of  the  ramming  the 
surplus  cement  shall  be  struck  off  and  the  last  layer  smoothed  with  a 
trowel  held  nearly  horizontal  and  drawn  back  with  sufficient  pressure 
to  make  its  edge  follow  the  surface  of  the  mold. 

(13)  The  above  are  to  be  considered  the  minimum  requirements. 
Unless  a  cement  has  been  recently  used  on  work  under  this  office,  bid- 


SPECIFICATIONS  FOR  NATURAL  CEMENTS.  281 

ders  will  deliver  a  sample  barrel  for  test  before  the  opening  of  the  bids. 
Any  cement  showing  by  sample  higher  tests  than  those  given  must 
maintain  the  average  so  shown  in  subsequent  deliveries. 

(14)  A  cement  may  be  rejected  which  fails  to  meet  any  of  the  above 
requirements.  An  agent  of  the  contractor  may  be  present  at  the  making 
of  the  tests,  or,  in  case  of  the  failure  of  any  of  them,  they  may  be 
repeated  in  his  presence.  If  the  contractor  so  desires,  the  engineer 
officer  may,  if  he  deems  it  to  the  interest  of  the  United  States,  have 
any  or  all  of  the  tests  made  or  repeated  at  some  recognized  standard 
testing  laboratory  in  the  manner  above  specified.  All  expenses  of 
such  tests  shall  be  paid  by  the  contractor,  and  all  such  tests  shall  be 
made  on  samples  furnished  by  the  engineer  officer  from  cement  actu- 
ally delivered  to  him. 

American  Society  for  Testing  Materials.     1904. 

11.  Definition. — This  term  shall  be  applied  to  the  finely  pulverized 
product  resulting  from  the  calcination  of  an  argillaceous  limestone  at 
a  temperature  only  sufficient  to  drive  off  the  carbonic-acid  gas. 

12.  Specific  gravity. — The  specific  gravity  of  the  cement  thoroughly 
dried  at  100°  C.  shall  be  not  less  than  2.8. 

13.  Fineness. — It  shall  leave  by  weight  a  residue  of  not  more  than 
10  per  cent  on  the  No.  100  and  30  per  cent  on  the  No.  200  sieve. 

14.  Time  of  setting. — It  shall  develop  initial  set  in  not  less  than 
ten  minutes,  and  hard  set  in  not  less  than  thirty  minutes,  nor  more 
than  three  hours. 

15.  Tensile   strength.— The     minimum     requirements     for    tensile 
strength  for  briquettes  1  inch  square  in  cross-section  shall  be  within 
the   following  limits,  and  shall  show  no  retrogression  in  strength  within 
the  periods  specified. 

NEAT  CEMENT. 

Age.  Strength. 

24  hours  in  moist  air 50-100  Ibs. 

7  days  (1  day  in  moist  air,  6  days  in  water) . .   100-200    '* 
28  days  (1  day  in  moist  air,  27  days  in  water) .  200-300    " 

1  PART  CEMENT,  3  PARTS  STANDARD  SAND. 

7  days  (1  day  in  moist  air,  6  days  in  water) . .     25-  75    *r 
28  days  (1  day  in  moist  air,  27  days  in  water) .     75-150    " 

16.  Constancy  of  volume. — Pats  of  neat  cement  about  3  inches  in 
diameter,  J  inch  thick  at  center,  tapering  to  a  thin  edge,  shall  be  kept 
in  moist  air  for  a  period  of  twenty-four  hours. 


282 


CEMENTS,  LIMES,  AND   PLASTERS. 


(a)  A  pat  is  then  kept  in  air  at  normal  temperature. 

(b)  Another  is  kept  in  water  maintained  as  near  70°  F.  as  prac- 

ticable. 

17.  These  pats  are  observed  at  intervals  for  at  least  twenty-eight 
days,  and,  to  satisfactorily  pass  the  tests,  should  remain  firm  and  hard 
and  show  no  signs  of  distortion,  checking,  cracking,  or  disintegrating. 

'  •  i* 

Comparison  and  Summary. 

It  is  of  interest  to  compare  the  requirements,  on  various  points, 
of  the  specifications  above  printed.  They  differ  considerably,  as  can 
be  readily  seen,  in  regard  to  fineness,  strength,  setting  time,  etc.,  etc. 

Definition. — Of  the  four  specifications  above  printed,  two  give  no 
definition  whatever  and  the  others  are  very  defective.  The  definition 
given  by  the  American  Society  for  Testing  Materials  would,  for  example, 
exclude  almost  every  good  natural  cement  in  the  country;  for  it  is 
only  the  very  low-limed  cements  that  are  burned  "at  a  temperature 
only  sufficient  to  drive  off  the  carbonic-acid  gas ". 

Specific  gravity. — Only  one  specification  contains  any  requirement 
in  regard  to  specific  gravity,  and  this  places  the  minimum  at  2.8.  So 
far  as  is  known  to  the  writer,  not  even  the  worst  possible  natural  cement, 
if  burned  at  all,  could  fall  much  below  this  point. 

Fineness. — The  differences  in  the  fineness  requirements  of  the  speci- 
fication printed  above,  as  well  as  of  several  other  important  specifica- 
tions, are  summarized  in  Table  137,  below.  The  requirements  of  the 
American  Society  for  Testing  Materials  (90  per  cent  through  100-mesh, 
70  per  cent  through  200-mesh)  are  high,  and  probably  cannot  be  eco- 
nomically attained  unless  modern  grinding  machinery  is  in  use  at  the 
mill.  With  tube  mills,  however,  this  fineness  can  be  readily  reached, 
and  the  tensile  strength  of  the  cement  is  greatly  improved. 

TABLE  137. 
FINENESS  REQUIRED  BY  VARIOUS  SPECIFICATIONS. 


Per  Cen 

t  Required 

to  Pass 

50-mesh. 

100-mesh. 

200-mesh. 

Engineer  Corps,  U.  S.  A  ,  1901  

80 

New  York  State  Canals   1896 

90 

80 

Rapid-transit  Subway,  New  York  City, 
Philadelphia  Department  Public  Works 

it                             it                      a               t  c 
K                             ((                      i  (               tt 

American  Society  for  Testing  Materials 

1900-1901.  .  . 
;,  1893  
1894-1895.  . 
1896-1897.  . 
,  1904  

95 
96 
99 
99 

85 

85 
90 
90 

60 

70 
70 

SPECIFICATIONS  FOR  NATURAL  CEMENTS. 


283 


Strength. — The  tensile  strength  required  is  also  highly  variable  in 
different  specifications.  These  variations  are  shown  in  the  summary 
below. 

TABLE  138. 
STRENGTH  REQUIRED  BY  VARIOUS  SPECIFICATIONS. 


Neat. 

1 

El. 

1  Day. 

7  Days. 

28  Days. 

7  Days. 

28  Days. 

N  Y  State  Canals 

65  Ibs 

125  Ibs 

N  Y  Subway 

125  Ibs 

200  Ibs 

100     " 

150     " 

Engineer  Corps,  U.S.A. 
Soc.  Testing  Materials  . 

50-100  Ibs. 

90     " 
100-200     " 

200    " 
200-300     " 

60     " 
25-75*  " 

150    " 
75-150*  " 

*  In  this  specification  the  mortar  mixture  is  1  cement,  3  sand. 

Product  actually  delivered. — Specification  requirements  are  made 
for  the  purpose  of  preventing  the  use  of  poor  material.  They  must 
therefore  be  set  low  enough  to  include  all  the  good  cement.  For  this 
reason  the  cement  supplied  to  any  important  work  is  usually  found, 
when  tested,  to  be  considerably  better  in  every  way  than  is  required 
by  the  specifications.  This  fact  is  well  brought  out  by  the  following 
tables,  which  give  the  experience  of  two  important  pieces  of  work. 

TABLE  139. 
CEMENT  SUPPLIED  TO  NEW  YORK  RAPID-TRANSIT  SUBWAY,  1900-1901. 


1900. 

1901. 

Barrels  received 

5000 

10,920 

Neat  cement: 
Briquettes  broken 

411 

750 

'  '          passed  
"          failed  ...     .. 

363 
48 

750 
0 

7  days,  specified  
7     '  '       average  test  
28  days,  specified 

125  Ibs. 
172     " 

200     " 

125  Ibs. 
215    " 

200     "   ' 

28     '  '       average  test  

1  cement,  1  sand: 
Briquettes  broken      

249    " 
138 

322    " 

882 

passed  

134 

882 

failed  

4 

0 

7  days    specified 

10€  Ibs 

100  Ibs 

7              average  test.  .... 
28              specified        

118    " 
150    " 

218    " 
150     " 

28              average  test  

215    " 

350    " 

284 


CEMENTS,  LIMES,  AND   PLASTERS. 


TABLE  140. 
SUMMARY  OF  NATURAL-CEMENT  TESTS,  1897-1900  (N.  Y.  STATE  ENGINEER). 


Locality. 

Number 
of  Tests. 

Fineness. 
Per  Cent  Passing 

Set. 

Tensile  Strength, 
1  Cement,  1  Sand. 

50-mesh. 

100-mesh 

Initial. 

Final. 

7  Days. 

28  Days. 

Ulster  Co  ,  N  Y  

215 
12 
3 
54 
1 

95.0 
92.2 
91.8 
93.6 
92.0 

90.0 

88.2 

84.6 
80.5 
85.5 
81.8 

80.0 

33 
23 

27 
18 
30 

5 

56 
41 
40 

31 
45 

81 

113 

122 
104 
61 

65 

196 
226 
263 
216 
131 

125 

SchoharieCo.,N.  Y.... 
Onondaga  Co.,  N.  Y.  .  . 
Erie  Co  ,  N  Y  

Lehigh  district,  Pa  
Specified  requirements. 

CHAPTER  XXI. 

HISTORY,   STATISTICS,  AND  PROSPECTS   OF  THE  NATURAL-CEMENT 

INDUSTRY. 

History  of  the  Industry. 

NATURAL  cements  were  first  made  in  England  and  France  about  1800, 
and  for  a  time  the  industry  developed  quite  rapidly.  In  the  United 
States  the  first  manufacture  was  in  1819,  the  discovery  of  the  raw 
material  being  due  directly  to  the  construction  of  the  Erie  Canal. 

When  the  construction  of  the  Erie  Canal  was  first  undertaken, 
the  use  of  ordinary  lime  as  a  mortar  material  was  contemplated.  As 
a  large  amount  of  lime  would  be  used  for  this  purpose,  many  lime- 
stone-beds throughout  the  State  were  examined  and  tested.  Good 
limes  were  found  to  be  available  at  many  points  along  the  course  of 
the  canal,  and  the  engineers  had  apparently  no  expectation  of  finding 
a  better  material.  During  the  progress  of  work  on  the  middle  section 
of  the  canal,  however,  it  was  found  that  the  lime  burned  from  a  cer- 
tain stone  refused  to  slake.  The  quarry  from  which  this  stone  came 
had  been  opened  on  the  land  of  T.  Clarke,  in  the  town  of  Sullivan, 
Madison  County,  in  a  bed  of  limestone  which  to  all  appearances  was 
satisfactory  enough. 

The  failure  on  the  part  of  the  contractor  to  deliver  the  lime  brought 
the  matter  to  the  attention  of  Benjamin  Wright,  engineer  in  charge 
of  the  middle  division,  and  Canvass  White,  one  of  his  two  associates. 
Fortunately,  Mr.  White  had  visited  England  in  order  to  secure  as  much 
information  as  possible  concerning  the  materials  and  methods  then 
employed  in  the  execution  of  great  public  works,  and  in  the  course 
of  this  visit  he  had  devoted  considerable  time  to  a  study  of  the  various 
limes  and  cements  used  as  mortar  materials.  Parker's  "  Roman  cement" 
had  then  passed  the  experimental  stage,  and  in  both  England  and 
France  natural  cement  was  gradually  but  steadily  supplanting  lime 
as  an  engineering  material  The  cost  of  Parker's  cement,  however, 
was  an  obstacle  to  its  extensive  use. 

Because  of  this  preliminary  acquaintance  with  the  subject,  Mr. 
White  was  peculiarly  well  fitted  to  cope  with  the  difficulty  which  had 

285 


CEMENTS,  LIMES,  AND  PLASTERS. 

presented  itself  in  Madison  County.  He  visited  the  Clarke  quarry, 
examined  and  tested  both  the  quarry  stone  and  the  burned  product, 
and  decided  that  the  obstinate  lime  was  really  a  high-grade  natural 
cement,  which  required  only  grinding  to  make  it  fit  /or  use.  Tests 
on  a  larger  scale  soon  proved  that  his  conclusion  was  correct,  and  the 
first  American  natural  cement  was  put.  to  extensive  use  hi  the  locks 
and  walls  of  the  middle  section  of  the  canal  during  the  years  1818-1819. 

Fortunately,  we  have  a  contemporary  professional  estimate  of  the 
value  of  this  material.  Wright,  in  a  letter  dated  in  1820,  summarizes 
the  facts  regarding  White's  cement,  stating  that  it  '**is  found  to  be  a 
superior  water  cement,  and  is  used  very  successfully  in  the  stonework 
of  the  Erie  Canal,  and  believed  to  be  equal  to  any  of  the  kind  found  in 
any  other  country.  It  is  pulverized  (as  it  will  not  slack)  and  then  used 
by  mixing  two  parts  lime  and  one  part  sand.  It  hardens  best  under 
water,  and  it  is  believed  its  properties  are  partially  lost  if  permitted 
to  dry  suddenly,  or  if  not  used  soon  after  mixing/7 

Eighty  years  of  testing  devices  have  hardly  given  us  a  more  sat- 
isfactory summary  of  the  properties  of  natural  cements  than  is  con- 
tained in  Wright's  last  sentence. 

Another  contemporary  account  (1821)  states  that  "the  price  of  this 
lime,  pulverized  and  burnt  and  delivered  at  Utica,  is  20  cents  the  bushel." 

Mr.  White  took  out  a  patent  on  this  cement  and  for  several  years 
a  controversy  raged  as  to  the  tenability  of  this  patent.  This  was  finally 
settled,  so  far  as  the  State  of  New  York  was  concerned,  by  the  action 
of  the  legislature.  In  1825  the  patent  rights  for  the  State  of  New  York 
were  purchased  from  Mr.  White  for  the  sum  of  $10,000  by  the  State 
and  immediately  thrown  open  to  the  free  use  of  the  citizens  of  New 
York 

It  is  pleasant  to  know  that  the  discovery  and  prompt  utilization 
of  this  new  material  by  White  and  Wright  were  rewarded  with  equal 
promptness  by  their  professional  advancement  on  the  canal  work. 

The  chemical  character  of  this  first  American  natural  cement  is  estab- 
lished by  an  analysis  made  in  1822  by  Seybert  of  a  sample  of  the  lime- 
stone used  in  its  preparation.  The  analysis  gave  the  following  results: 

8ilica(SiO2) , .  11,766 

Alumina  (ALA) 2.733 

Iron  oxide  (FejD,) 1 .500 

Lime  (CaO). . .  „ . 25.000 

Magnesia  (M«O) 17.833 

Carbon  dioxide  (CO.) 39.333 

Moisture. 1.300 

99.665 


HISTORY  OF  THE  N ATI  KVL-CEMENT  INDUSTRY.  287 

If  this  analysis  be  accepted  as  representative  of  the  rock  used,  the 
resulting  cement  would  have  a  Cementation  Index  of  0.74,  and  at  the 
present  day  would  be  regarded  as  a  hydraulic  lime  rather  than  as  a- 
natural  cement. 

The  use  of  the  Madison  County  cement  on  the  canal  stimulated  search 
for  other  deposits  of  cement  rock.  In  Wright's  letter  he  states  that 
this  rock  "is  found  in  great  abundance  in  the  counties  of  Madison,  Onon- 
daga,  and  Cayuga".  He  thus  outlined  what  has  since  been  the  natural- 
cement  district  of  central  New  York.  Later  in  the  same  letter  Wright 
remarks:  "I  do  not  know  that  it  is  found  in  the  count  ii  >  r  .. 
but  presume  from  the  geological  character  of  that  country  it  may  be 
found  in  all  the  country  west  to  Niagara,  and  probably  farther  west." 
Within  a  few  years  this  proved  to  be  a  fact,  cement  rock  being  dis- 
covered in  Krie  County,  in  the  extreme  western  part  of  the  State. 

The  first  natural  cement  manufactured  in  Krie  County  was  made  in 
ivj-l  at  \Yilliam-ville.  the  quarry,  kiln,  anil  mill  being  near  the  creek. 
In  1839  Jonathan  Delano  erected  cement  works  at  Falkirk,  near  Akron, 
in  which  he  made  about  2000  barrels  of  cement  the  first  year.  He 
furnished  the  cement  for  the  feeder  dam  at  Tonawanda  Creek  and  for 
the  (Jenesee  Valley  Canal.  In  1843  the  business  passed  into  the 
hands  of  James  Montgomery,  who  increased  the  output  to  10,000  barrels 
a  year.  The  business  afterwards  came  into  the  possession  of  Enos 
Newman,  a  partner  of  Montgomery,  and  has  been  in  his  family  ever 
since. 

In  1854,  H.  Cummings  &  Son  established  a  natural-cement  plant 
at  Akron,  which  was  operated  for  several  years.  This  plant  was  succeeded 
by  another,  managed  by  sons  of  the  founder.  The  Akron  plant  was 
sold  to  the  Akron  Cement  Company  in  1871,  and  the  Cummings  brothers 
erected  another  plant  about  two  miles  west  of  Akron. 

The  first  natural  cement  made  within  the  present  limits  of  Buffalo 
was  manufactured  in  1850  by  Warren  Granger.  His  plant  was  located 
near  Scajaquada  Creek,  just  below  the  Main  Street  bridge,  in  what  is 
now  Forest  Lawn  Cemetery.  In  1874  Lewis  J.  Bennett  commenced 
the  manufacture  of  natural  cement  at  Buffalo  Plains,  near  Main  Street. 
This  establishment,  which  has  been  carried  on  continuously  under  the 
control  of  the  Bennett  family,  is  now  incorporated  as  the  Buffalo  Cement 
Company, 

In  following  out  the  history  of  the  western  New  York  cement  in- 
dustry from  1824  to  the  present  time,  we  have  necessarily  passed  by  the 
inauguration  of  manufacture  in  the  greatest  of  all  the  natural-cement 
districts — the  Rosendale  region  of  eastern  New  York.  Third  among 


288 


CEMENTS,  LIMES,  AXD  PLASTERS. 


the  districts  in  point  of  age,  it  soon  became  first  as  a  producer,  and  has 
ever  since  maintained  a  high  standard  in  both  the  quality  and  quantity 
of  its  output. 

The  discovery  of  cement  rock  and  the  commencement  of  manufac- 
ture of  natural  cement  in  the  Rosendale  district  took  place  apparently 
about  1825,  though  there  is  considerable  uncertainty  as  to  the  exact 
date  to  be  assigned.  * 

TABLE  141. 
DATES  OF  ESTABLISHMENT  OF  NATURAL-CEMENT  INDUSTRIES  IN  VARIOUS  STATES. 


State. 

Location. 

Date. 

California 

Benicia 

I860 

Connecticut 

Kensington   . 

1826 

Georgia 

Howard  

1851 

it 

Rossville.  .  :  

1901 

Illinois 

Utica 

1838 

Indiana-Kentucky 

Louisville 

1829 

Kansas     

Fort  Scott  

1868 

Maryland  

Round  Top  

1837 

Cumberland  

1836 

tt 

Antietam  . 

1888 

Minnesota 

Mankato 

1883 

<  < 

Austin 

1895 

New  Mexico 

Springer 

1899 

New  York  

Akron,  Erie  County     ... 

183£ 

«        « 

Williams  ville,  Erie  County.  

1824 

K        it 

Buffalo,  Erie  County  

1850 

tt       tt 

Onondaga-Madison  Counties 

1818 

tt        tf 

Rosendale  district 

1825 

it        n 

Howe's  Cave  „    .    . 

1870 

North  Dakota    

Pembina  

1895 

Ohio 

Defiance 

1846 

1  1 

Barnesville 

1858 

Pennsylvania 

Williamsport         

1831 

<  t 

Lebanon  (?)   

1825  (?) 

it 

Lehigh  district  

1850 

Virginia 

Balcony  Falls 

1848 

West  Virginia 

Shepherdstown 

1829 

Wisconsin 

Milwaukee 

1875 

The  industry,  however,  had  not  secured  so  firm  a  foothold  in  the 
district  by  1837  as  might  be  expected,  for  in  1843  Mather,  of  the  First 
Geological  Survey  of  New  York  State,  referred  to  the  immediate  past 
as  follows:  "When  making  the  reconnaissance,  soon  after  the  commence- 
ment of  the  geolgical  survey,  the  business  had  but  commenced,  and  there 
was  no  cement  manufactured  on  the  Rondout  except  at  Lawrenceville, 
and  there  but  few  kilns  were  in  operation.  It  was  not  then  known  to 
the  inhabitants  that  the  cement  rock  was  abundant  except  at  and  near 
these  quarries  until  some  of  them  were  then  informed  of  its  inexhausti- 


STATISTICS  OF  THE  AMERICAN  INDUSTRY.  289 

ble  quantities.  Even  now  few  are  aware  of  the  great  extent  of  the  rock 
and  still  fewer  understand  how  to  trace  out  the  situation  of  favorably 
located  new  quarries." 

During  the  six  years  that  had  elapsed  since  1837,  however,  the  in- 
dustry seems  to  have  grown  rapidly,  for  in  his  final  report  (1843)  Mather 
states  that  sixteen  firms,  working  sixty  kilns,  were  then  operating  in 
the  Rosendale  district.  He  estimated  the  product  at  500,000  to  600,000 
barrels  per  year,  and  notes  that  about  700  men  were  employed  in  the 
quarries,  in  the  mills,  and  in  handling  the  cement. 

After  the  industry  had  become  established  in  New  York,  it  was  taken 
up  soon  in  several  other  States.  It  is  a  noteworthy  fact,  first  pointed 
out  by  Mr.  Lesley,  that  all  these  early  plants  were  located  along  canals, 
and  that  in  each  case  the  natural-cement  rock  was  discovered  through 
search  for  a  satisfactory  mortar  material  for  canal  masonry. 

Statistics  of  the  American  Industry. 

Since  within  very  wide  limits  of  composition  any  clayey  limestone 
will  give  a  natural  cement  on  burning,  it  can  readily  be  seen  that  sat- 
isfactory natural-cement  materials  must  be  widely  distributed  and 
of  common  occurrence.  Hardly  a  State  is  entirely  without  limestones 
sufficiently  clayey  to  be  available  for  natural-cement  manufacture. 
The  sudden  rise  of  the  American  Portland-cement  industry,  however, 
has  acted  to  prevent  any  great  recent  expansion  of  the  natural-cement 
industry.  It  would  be  difficult  to  place  a  new  natural  cement  on  the 
market  in  the  face  of  competition  from  both  Portland  cement  and  from 
the  older  and  well-established  brands  of  natural  cement.  Such  new 
natural-cement  plants  as  have  been  started  within  recent  years  have 
mostly  been  located  in  old  natural-cement  districts,  where  the  accu- 
mulated reputation  of  the  district  would  help  to  introduce  the  new 
brand.  The  only  exceptions  to  this  rule,  indeed,  were  the  Pembina 
plant  in  North  Dakota,  the  Rossville  plant  in  Georgia,  and  a  plant  in 
the  State  of  Washington.  Of  these  the  Pembina  plant  was  established 
with  the  intention  of  making  Portland  cement,  but  the  raw  materials 
soon  proved  to  be  unsuitable,  and  the  plant  was  converted.  The  plant 
in  "Washington  is  located  in  an  area  where  any  kind  of  cement  is  readily 
salable.  The  Rossville  plant  was  built  by  an  Akron,  N.  Y.,  cement 
manufacturer,  to  utilize  a  peculiarly  satisfactory  natural-cement  rock. 

The  following  table  taken  from  the  annual  volume  on  Mineral 
Resources,  issued  by  the  U.  S.  Geological  Survey,  shows  the  quantity 
and  value  of  the  natural  cement  produced  in  the  United  States  in  1901, 
1902,  and  1903: 


290 


CEMENTS,  LIMES,  AND  PLASTERS. 


§ 

3 

CM  O  CO  1C  OS  O        OS        COOS        I-H        CO 
O  O  00  *O  I-H  iO        CM        l>  CO        CO        I> 

•<^  t—  CO  CO  CO  ir—        I-H        '^t|l>       (N        CO 
rH 

3,675,520 

i 

CO 

1 

^isslsi  H  ii  1  i 

£ 

1 

I-H 

d 

1 

Jj   00  ^'CO  CNJ  CO  l>        i—  t         COCO        -^         CO 
fQ         lO^CN.CNi—  i        •$*              CO^                   CO 

| 

o                  *-* 

<< 

L* 

Number 
of 
Works. 

CN  CO  »O  (N  -^f  CM        OT-H(Mt>-CN(Ni-HC<J 

i-H                                 <M 

*O 

CO 

i  H 

O            -u        Oi 

1-1          **     'Si 

^3            £       4j 

iS 

h 

w 

. 

rfiiOCOOOO        CO           -OS        O>OOO 

§ 

co" 
»-H 

2 

i-HCOOSOOI>        >O            !o        OCNCM 
CO  *O  CO  00  iO  CO        CO           .  rf        CM  CO  CO 

1 

1-H                 "rt         rH 
tn                   ^           O 

"ri            M      5 

p 

£ 

•< 

•t 

OS 
i—  i 

1 

Quantity. 

iCOcOOOO        O           'CO        OOCO 
^•OOCMCOO^O        l>           iOS        COOOCO 

pq       co  i>-  T—  i  Tfi  I-H      10        .  i>              Tt1 
j-*                     co"         ; 

1 

1 
00* 

|     1  3 
•a     s  « 

1  11 

S        -a  •  o 

2               ^ 

§ 
fc 

1*1 

&   > 

CM  CO  iO  CM  "^  CM        OS  i—  i  CM  CO  r-i  d  rH  CM 

T-4                                                    1—  1 

§ 

1    1  j 

g       &£* 

H 
fc 

I>  CO  O  CM  >O  O        CO        O  T}H                    00 
CO  CO  O  CO  CO  CO        CO        O  *-O                    00 

00 

S 

i 

o 

M 

3 

CO  t^  CM  t^*  *O  CO        t>*        CM  CO                    CM 

^f  00  iO  OS  1>  cO        i—  i        CO  t>                   00 

€®  i-H  |>           T-H                   T—  1                   CO                           rH 

8 

o 
co" 

n  jii 

1 

-/    1>*  ^  O  CO  C^l  O         CO         CO  CO                     CM 

-^jiOOOOiOCOO         T-H         OCO                     O 

CO 

S3 

is  ^s 

SJ§  -i^§ 

h 
O 

g 

I 

c3  ^O  CO  ^O  l^»  ^O  CM        CO        O  "^t1                    00 

PQ            ^  T^  T-H  CO  i"H          CM          ^^  OS                         Tt^ 

i 

i  ifll 

O 

1   3 

^Iplfu 

'RODU 

1^ 

f 

MH 

2"S  S-S.S  c-1"1  ft 

JZ   Q'^   S   tiC  -j   •   Q) 

g'?'   cS   ^;^5   C'-'S 

^<~  1^^  °"ffl  d 

•    •  o    

°     °  o  °  *.9*1 

II  "sjj  JN  i! 

1 

^    ;    :    •    ;    ;  "o     *g        ;'S    • 

1 

Illlpli 

iuHiM 

^^H^^HHH 

8 

STATISTICS  OF  THE  AMERICAN  INDUSTRY. 


291 


"The  single  cement  plant  in  North  Dakota  has  a  production  which 
for  1903  has  been  combined  with  that  of  the  only  plants  producing 
natural  cement  in  Kansas  and  Texas.  The  other  States  stand  in  the 
table  exactly  as  the  reported  productions  are  given. 

"The  total  results  of  combined  productions  are  placed  against  those 
States  which  contributed  the  greater  proportion  of  cement  to  make  the 
entire  quantity." 

The  following  figures,  also  taken  from  the  volume  on  Mineral  Resources, 
issued  annually  by  the  U.  S.  Geological  Survey,  are  of  interest  in  this 
connection : 

TABLE  143. 

TOTAL  PRODUCTION  OF  NATURAL-ROCK,  PORTLAND,  AND  SLAG  CEMENT  IN  THE 
UNITED  STATES,  1818-1904. 


Year. 

Natural, 
Barrels. 

Portland, 
Barrels. 

Puzzolan 
or  Slag, 
Barrels. 

1818  to  1830  

300  000 

1830  '  '  1840  

1,000,000 

1840  "  1850  

4,250,000 

1850  "  1860  

11,000,000 

1860  "  1870 

16  420  000 

1870  "  1880 

22  000  000 

82000 

1880 

2  030  000 

42000 

1881 

2  440  000 

60000 

1882 

3  165  000 

85000 

1883  .  .  . 

4  190  000 

90  000 

1884  .  . 

4  000  000 

100  000 

1885  

4  100  000 

150  000 

1886  .   ... 

4,186,152 

150  000 

1887     

6,692,744 

250  000 

1888   

6,253,295 

250  000 

1889  '  

6,531,876 

300,000 

1890  

7,082,204 

335,000 

1891  

7,451,535 

454,813 

1892  

8,211,181 

547,440 

1893  

7,411,815 

590,652 

1894  

7,563,488 

798,757 

1895  

7,741,077 

990,324 

1896  

7,970,450 

1,543,023 

12,265 

1897 

8,311,688 

2,677,775 

48329 

1898 

8,418,924 

3,692,284 

150  895 

1899 

9,868,179 

5,652,266 

335,000 

1900        

8,383,519 

8,482,020 

446,609 

1901     

7,084,823 

12,711,225 

272,689 

1902  

8,044,305 

17,230,644 

478,555 

1903  

7,030,271 

22,342,973 

525,896 

1904      .  . 

4  866,331 

26,505,881 

303,015 

Total  

213,998,857 

106,114,077 

2,573,283 

"The  figures  for  natural-rock  and  Portland  cement  in  this  table 
through  the  year  1896  are  taken  from  a  statement  made  by  Mr.  Uriah 


CEMENTS,  LIMES,  AND   PLASTERS. 

Cummings,  of  Akron,  N.  Y.,  in  his  volume  entitled  '  American  Cements, 
1898',  on  page  288."  The  remainder  of  the  table  is  compiled  from  the 
United  States  Geological  Survey  reports  on  the  production  of  cement. 

In  making  a  comparison  it  must  of  course  be  borne  in  mind  that 
the  barrel  of  Portland  cement  contains  380  Ibs.  net,  while  the  natural- 
cement  barrel  varies  from  240  Ibs.  to  300  Ibs. 

.-•'-•  .  •          v* 

Prospects  of  the  Industry. 

Reference  to  the  tables  of  statistics  on  preceding  pages  will  show 
that  the  natural-cement  production  of  the  United  States  has  been  prac- 
tically stationary  since  1890.  During  this  period,  while  the  annual 
American  production  of  Portland  cement  has  advanced  from  335,000 
barrels  to  22,342,973  barrels,  the  annual  production  of  natural  cement 
has  varied  between  7,030,271  and  9,868,179  barrels,  the  lowest  pro- 
dution  for  any  year  being  that  of  1903.  In  view  of  these  facts  and  of 
freely  expressed  prophecies  that  the  natural-cement  industry  is  gradu- 
ally nearing  its  end,  it  seems  desirable  to  sum  up  the  prospects  of  the 
industry  from  the  viewpoint  of  a  disinterested  outsider. 

Engineers,  both  in  text-books  and  in  conversation,  bring  two 
charges  against  the  natural  cements  as  a  class.  Since  the  fate  of  the 
natural-cement  industry  will  be  decided  finally  by  the  verdict  of  the 
engineer  who  uses  the  product,  it  will  pay  to  critically  examine  these 
charges.  The  faults  alleged  are:  (1)  lack  of  strength  as  compared 
with  Portland  cements,  and  (2)  lack  of  uniformity  in  both  composition 
and  strength. 

It  may  as  well  be  admitted  that  both  of  these  Charges  are  true  as 
regards  the  majority  of  natural  cements  as  now  made,  but  the  writer 
cannot  admit  either  that  these  faults  are  universal,  or  that  they  are 
unavoidable. 

In  regard  to  the  first  point  an  advocate  of  the  natural  cements 
could  point  out  that  three  brands  of  natural  cements  are  now  regu- 
larly advertised  and  sold  as  Portland  cements;  that  they  have  been 
tested  for  use  in  both  State  and  Federal  public  works,  including  canals, 
locks,  dams,  and  breakwaters;  and  that  neither  State  nor  army 
engineers  seem  to  have  even  suspected  that  they  are  not  Portland 
cements.  This  is  surely  a  proof  that  all  natural  cements  are  not  so 
low  in  strength  as  ta  be  readily  distinguished  from  Portlands  by  ordinary 
physical  tests.  So  far  as  lack  of  uniformity  is  concerned,  attention 
might  be  called  to  several  American  brands  of  natural  cements  whose 
variation  in  composition  and  strength  is  no  more  than  is  shown  by  the 


PROSPECTS  OF  THE  NATURAL-CEMENT  INDUSTRY.  293 

average  brar.d  of  Portland  cement.  The  faults  charged  against  the 
natural  cements  are  not,  therefore,  universal. 

There  remains  to  be  considered  the  second  point:  whether,  when 
these  faults  do  occur,  they  are  unavoidable  and  inherent  in  the  idea 
of  a  natural  cement,  or  whether,  on  the  other  hand,  they  can  be 
avoided  economically.  To  the  present  writer  it  seems  obvious  that 
most  brands  could,  with  sufficient  care,  be  freed  from  both  faults,  and 
that  this  improvement  could  be  carried  out  without  raising  the  cost  of 
manufacture  to  a  profitless  point. 

In  regard  to  chemical  control  of  the  raw  material  and  product,  it 
can  be  said  that,  with  very  few  exceptions,  none  is  attempted  in  the 
American  natural-cement  industry.  The  plants  of  the  Lehigh  district 
of  Pennsylvania,  which  are  run  in  connection  with  Portland-cement 
plants,  are,  of  course,  better  off  in  this  respect  than  the  others.  Exclud- 
ing these  Pennsylvania  plants,  there  is,  to  the  writer's  knowledge,  only 
one  American  natural-cement  plant  which  employs  a  chemist.  It  seems 
only  right  that  the  name  of  this  honorable  exception  should  be  published 
— it  is  the  Pembina  Cement  Company,  of  North  Dakota. 

Careful  analyses  of  the  raw  material  and  the  product  will,  as  pointed 
out  earlier  in  this  volume,  enable  the  manager  to  select  the  proper  burn- 
ing-point for  his  rock,  and  to  correct  any  defects  in  its  composition. 
Few  quarries  show  rock  of  such  uniform  character  that  it  can  all  be 
burned  at  the  same  temperature,  yet  at  most  plants  this  is  jus£  what 
is  attempted. 

The  product  must-  also  be  given  more  careful  treatment  after  burning, 
both  in  regard  to  seasoning  and  grinding.  At  the  present  day  there 
is  no  reason  why  a  coarsely  ground  or  unsound  natural  cement  should 
be  put  on  the  market.  Economical  fine-grinding  machines  are  obtain- 
able and  should  be  installed.  They  will  soon  repay  their  first  cost, 
and  their  high  power  consumption  per  unit  is  more  than  made  up  by 
the  great  increase  in  the  amount  and  quality  of  the  output. 


PART  VI.    PORTLAND   CEMENT. 


CHAPTER  XXII. 
PORTLAND  CEMENT:    PRELIMINARY  STATEMENTS. 

IN  the  chapters  of  the  present  section  the  raw  materials,  methods 
of  manufacture,  and  properties  of  Portland  cement  will  be  taken  up 
and  discussed  in  turn.  In  order  that  the  statements  made  in  these 
chapters — and  particularly  in  those  on  raw  materials — may  be  clearly 
understood,  it  seems  advisable  to  preface  the  section  with  a  brief 
explanation  regarding  the  definition,  composition,  and  constitution  of 
Portland  cement.  This  brief  explanation  is  accordingly  given  in  the 
present  chapter,  while  in  Chapters  XXIX  and  XXXVIII  the  subject  of 
composition  and  constitution  will  be  discussed  in  the  greater  detail 
warranted  by  their  importance. 

Origin  of  the  name  "  Portland  ". — In  1824  Joseph  Aspdin  took  out 
a  patent  in  England  on  the  manufacture  of  a  cement  by  calcining  a 
mixture  of  limestone  and  clay.  To  the  resulting  product  he  gave  the 
name  " Portland",  in  allusion  to  a  fancied  (and  in  reality  very  slight) 
resemblance  between  the  set  cement  and  the  famous  oolitic  limestone 
so  extensively  quarried  for  building  purposes  at  Portland,  England, 
and  known  to  all  English  architects  and  engineers  as  " Portland  stone". 

" Portland"  cement  obtained  its  name,  therefore,  because  it  looked 
like  Portland  stone,  and  not  because  Portland  was  the  place  of  its  manu- 
facture. On  the  contrary,  it  is  not  now,  and  never  has  been,  manu- 
factured at  either  Portland,  Me.,  Portland,  Ore.,  or  Portland,  England. 
This  statement  as  to  the  origin  of  the  name  may  seem  unnecessary; 
but  the  writer  has  found  many  contractors  or  other  useri  of  Portland 
cement  who  believed  that  the  only  proper  Portland  must  naturally 
be  made  at  Portland — a  belief  which  is  fostered  by  the  myriad  of  post- 
offices  and  villages  bearing  that  name  which  have  sprung  up  in  the 

wake  of  the  American  cement  industry. 

294 


UNITED 

SHOWING  L( 

PORTLAND  CEM9NT  PLANTS 


FIG.  63. 


[To  face  p.  2Q4. 


PORTLAND  CEMENT:  PRELIMINARY  STATEMENTS.  295 

Recurring  to  Aspdin's  work,  it  is  to  be  noted  that  his  original  patent 
did  not  specify  the  percentages  in  which  the  two  raw  materials  were 
to  be  mixed,  and  that  it  also  omitted  any  mention  of  the  high  tem- 
perature necessary  to  secure  a  good'  product.  The  earliest  Portland 
was  probably,  so  far  as  its  properties  were  concerned,  like  one  of  our 
poorer  low-limed  grades  of  natural  cements.  These  defects  were,  how- 
ever, overcome  when  Aspdin  took  up  the  manufacture  on  a  commercial 
scale,  and  before  1850  the  new  product  had  established  its  value.  In 
later  chapters  further  details  may  be  found  concerning  the  early  history 
and  growth  of  the  industry,  both  in  Europe  and  in  America. 

Present  use  of  the  term  "Portland". — While  there  is  at  present  a 
fairly  close  general  agreement  as  to  what  is  to  be  understood  by  the 
term  " Portland  cement",  a  few  points  of  importance  are  still  open 
questions.  Partly  in  consequence  of  this  uncertainty,  but  more  largely 
because  of  the  intense  imitativeness  of  specification-makers,  the  defini- 
tions of  the  term  given  in  specifications  and  text-books  are  usually 
vague  and  unsatisfactory. 

It  is  commonly  agreed  that  the  cement  mixture  must  consist  essen- 
tially of  lime,  silica,  and  alumina  in  proportions  which  can  vary  but 
slightly,  and  that  this  mixture  must  be  burned  at  a  temperature  which 
will  give  a  semi-fused  product — a  ' '  clinker ' ' .  These  points  must  therefore 
be  included  in  any  satisfactory  definition.  The  principal  point  regard- 
ing which  there  is  a  difference  of  opinion  is  whether  or  not  cements 
made  by  burning  a  natural  rock  without  previous  mixing  and  grinding 
can  under  any  circumstances  be  considered  true  Portlands.  The  ques- 
tion as  to  whether  the  definition  of  Portland  cement  should  be  drawn 
so  as  to  include  or  exclude  such  products  is  evidently  largely  a  matter 
of  convention;  but,  unlike  most  conventional  issues,  the  decision  has 
very  important  practical  consequences.  The  question  at  issue  may 
be  stated  as  follows: 

If  we  make  artificial  mixture  of  the  raw  materials  and  a  very  high 
degree  of  burning  the  criteria  on  which  to  base  our  definition,  we  must 
in  consequence  of  that  decision  exclude  from  the  class  of  Portland 
cements  certain  well-known  products  manufactured  at  several  points 
in  France  and  Belgium  by  burning  a  natural  rock  without  previous 
fine  crushing  or  artificial  mixture  and  at  a  considerably  lower  tem- 
perature than  is  attained  in  ordinary  Portland-cement  practice.  These 
"natural  Portlands"  of  France  and  Belgium  have  been  considered  Port- 
land cements  by  some  of  the  most  critical  authorities,  though  all  agree 
that  they  are  not  particularly  high-grade  Portlands.  So  that  a  definition 
based  upon  the  criteria  above  named  will  of  necessity  exclude  from 


296  CEMENTS,  LIMES,  AND   PLASTERS. 

our  class  of  Portland  cements  some  meritorious  products.  But,  on  the 
other  hand,  such  a  restricted  definition  would  have  decided  advantages. 

There  is  no  doubt  that  in  theory  a  rock  could  occur  containing  lime, 
silica,  and  alumina  in  such  uniformly  correct  proportions  as  to  always 
give  a  good  Portland  cement  on  burning.  Actually,  however,  such  a 
perfect  cement  rock  is  of  extremely  rare  occurrence.  As  above  stated, 
certain  brands  of  French  arid  •  Belgian*  "  Portland "  cements  are  made 
from  such  natural  rocks  without  the  addition  of  any  other  material; 
but  these  brands  are  not  particularly  high  grade,  and  in  the  better 
Belgian  cements  the  composition  is  corrected  by  th$  addition  of  other 
material  to  the  cement  rock  before  burning. 

The  following  definition  of  Portland  cement  is  of  importance  because 
•of  the  large  amount  of  cement  which  will  be  accepted  annually  under 
;the  specifications  *  in  which  it  occurs.  It  is  also  of  interest  as  being 
the  nearest  approach  to  an  official  definition  of  the  material  that  we 
have  in  this  country: 

"By  a  Portland  cement  is  meant  the  product  obtained  from  the 
heating  or  calcining  up  to  incipient  fusion  of  intimate  mixtures,  either 
natural  or  artificial,  of  argillaceous  with  calcareous  substances,  the 
calcined  product  to  contain  at  least  1.7  times  as  much  of  lime,  by  weight, 
as  of  the  materials  which  give  the  lime  its  hydraulic  properties,  and 
to  be  finely  pulverized  after  said  calcination,  and  thereafter  additions 
or  substitutions  for  the  purpose  only  of  regulating  certain  properties 
•of  technical  importance  to  be  allowable  to  not  exceeding  2  per  cent 
•of  the  calcined  product." 

It  will  be  noted  that  this  definition  does  not  require  pulverizing 
or  artificial  mixing  of  the  materials  prior  to  burning.  It  seems  prob- 
able that  the  Belgian  "natural  Portlands"  were  kept  in  mind  when 
these  requirements  were  omitted.  In  dealing  with  American-made 
cements,  however,  and  the  specifications  in  question  are  headed  "  Speci- 
fications for  American  Portland  Cement",  it  is  a  serious  error  to  omit 
these  requirements.  No  true  Portland  cements  are  at  present  manu- 
factured in  America  from  natural  mixtures  without  pulverizing  and 
artificially  mixing  the  materials  prior  to  burning.  Several  natural- 
cement  plants,  however,  have  placed  on  the  market  so-called  Port- 
land cements  made  by  grinding  up  together  the  underburned  and  over- 
burned  materials  formed  during  the  burning  of  natural  cements.  Sev- 
eral of  these  brands  contain  from  5  to  15  per  cent  of  magnesia,  but 
«even  if  that  fact  be  disregarded,  there  is  no  warrant  or  excuse  for  con- 

*  Professional  Paper  No.  28,  Corps  of  Engineers,  U.  S.  A.f  p.  30. 


PORTLAND  CEMENT:  PRELIMINARY  STATEMENTS.  297 

Bidering  such  products  as  true  Portland  cements.  Nevertheless,  there 
is  absolutely  nothing  in  the  definition  above  quoted  that  would  pre- 
vent their  acceptance ;  and  as  a  matter  of  fact  at  least  one  of  these  brands 
has  been  submitted,  accepted,  and  used  under  these  specifications. 

The  definition  above  discussed  is  fairly  typical  of  those  now  to  be 
found  in  American  cement  specifications. 

The  definition  below  has  recently  (1903-1904)  been  adopted  by 
the  Association  of  German  Portland  Cement  Manufacturers: 

Portland  cement  is  a  hydraulic  cementing  material  with  a  specific 
gravity  of  not  less  than  3.10  in  the  calcined  condition,  and  containing 
not  less  than  1.7  parts  by  weight  of  lime  to  each  one  part  of  silica  -f  alu- 
mina +  irgn  oxide,  the  material  being  prepared  by  intimately  grinding 
the  raw  ingredients,  calcining  them  to  not  less  than  clinkering  tem- 
perature, and  then  reducing  »to  proper  fineness. 

In  view  of  the  conditions  above  noted,  the  writer  believes  that  the 
following  definition  will  be  found  more  satisfactory  than  those  now  in 
use  for  insertion  as  a  preliminary  requirement  in  cement  specifications. 

"  Definition  of  Portland  cement. — By  the  term  Portland  cement, 
as  used  in  these  specifications,  is  to  be  understood  the  product  obtained 
by  finely  pulverizing  clinker  produced  by  burning  to  semi-fusion  an 
intimate  artificial  mixture  of  finely  ground  calcareous  and  argillaceous 
materials,  this  mixture  consisting  approximately  of  three  parts  of  lime 
carbonate  (or  an  equivalent  amount  of  lime  oxide)  to  one  part  of  silica, 
alumina,  and  iron  oxide.  The  ratio  of  lime  (CaO)  in  the  finished  cement 
to  the  silica,  alumina,  and  iron  oxide  together  shall  not  be  less  than 
1.6  to  1,  or  more  than  2.3  to  1." 

The  ratios  of  lime  to  silica,  alumina,  and  iron  oxide  given  in  the 
last  sentence  of  the  above  definition  have  been  determined  by  exam- 
ination of  a  large  series  of  analyses  of  standard  brands  of  American 
Portland  cements,  and  it  is  very  unlikely  that  any  good  Portland,  as 
at  present  made,  will  have  a  ratio  falling  outside  the  limits  above  given. 
Occasionally,  however,  analyses  will  come  very  close  to  these  limits, 
values  of  1.64  and  2.29  respectively  having  been  obtained  from  good 
brands.  A  value  as  low  as  1.6  to  1.7  means  a  low-testing  but  abso- 
lutely safe  cement.  Values  above  2.0  will  include  the  high-testing 
brands. 

Composition  and  constitution. — Portland  cements  may  be  said  to  tend 
toward  a  composition  approximating  to  pure  tricalcic  silicate  (3CaO,SiO2) 
which  would  correspond  to  the  proportion  CaO  73.6  per  cent,  SiO2 
26.4  per  cent.  As  can  be  seen,  however,  from  the  analyses  quoted  in 
Chapter  XXXVIII  actual  Portland  cements  as  at  present  made 


298  CEMENTS,  LIMES,  AND  PLASTERS. 

differ  in  composition  very  markedly  from  this.  Alumina  is  always 
present  in  considerable  quantity,  forming  with  part  of  the  lime  the 
dicalcic  aluminate  (2CaO,  A12O3).  This  would  give,  as  stated  by  New- 
berry,  for  the  general  formula  of  a  pure  Portland, 

X(3CaO,SiO2),      F(2CaO,Al2O3). 

But  the  composition  is  still  further  complicated  by  the  presence 
of  accidental  impurities  or  intentionally  added  ingredients.  These 
last  may  be  simply  adulterants,  or  they  may  be  added  to  serve  some 
useful  purpose.  Calcium  sulphate  is  a  type  of  the  latter  class.  It 
serves  to  retard  the  set  of  the  cement  and  in  small  quantities  appears 
to  have  no  injurious  effect  which  would  prohibit  its  use  for  this  pur- 
pose. In  dome  kilns,  sufficient  sulphur  trioxide  is  generally  taken  up 
by  the  cement  from  the  fuel  gases  to  obviate  the  necessity  for  the  latter 
addition  of  calcium  sulphate,  but  in  the  rotary  kiln  its  addition  to  the 
ground  cement,  in  the  form  of  either  powdered  crude  gypsum  or  plaster 
of  Paris,  is  a  necessity. 

Iron  oxide,  within  reasonable  limits,  seems  to  act  as  a  substitute 
for  alumina,  and  the  two  may  be  calculated  together.  Magnesium 
carbonate  is  rarely  entirely  absent  from  limestones  or  clays,  and  mag- 
nesia is,  therefore,  almost  invariably  present  in  the  finished  cement 
but  in  small  percentage.  Though  magnesia,  when  magnesium  car- 
bonate is  burned  at  low  temperature,  is  an  active  hydraulic  material 
(see  Chapter  XII)  it  does  not  normally  combine  with  silica  or  alumina 
at  the  clinkering  heat  employed  in  Portland-cement  manufacture.  At 
the  best  it  is  an  inert  and  valueless  constituent  in  the  normal  Portland  * 
cement ;  many  regard  it  as  positively  detrimental  in  even  small  amounts, 
and  because  of  this  feeling  manufacturers  prefer  to  carry  it  as  low  as- 
possible.  In  amounts  of  less  than  3^  per  cent  to  5  per  cent  it  is  cer- 
tainly harmless — and  American  Portlands  from  the  Lehigh  district 
usually  reach  well  up  toward  that  limit.  In  European  practice  it  is 
carried  somewhat  lower. 

Cementation  Index. — In  discussing  the  hydraulic  limes  and  natural 
cements,  use  has  been  made  of  the  Cementation  Index,  a  device  which 
affords  an  easy  means  of  comparing  the  hydraulic  and  other  proper- 
ties of  various  cements.  In  dealing  with  Portland  cement,  this  device 

*  This  statement  should  not  be  construed  to  mean  that  it  is  impossible  to 
make  a  good  cement  of  the  Portland  type,  but  containing  high  percentages  of 
magnesia,  for  this  very  possibility  will  be  discussed  on  a  later  page  (p.  348).  But 
such  a  magnesia  Portland  will,  of  necessity,  differ  quite  markedly  both  in  prep- 
aration and  properties  from  the  lime  Portlands  now  in  use. 


PORTLAND  CEMENT:  PRELIMINARY  STATEMENTS.  299 

reaches  its  maximum  of  efficiency  and  becomes  of  great  service  in  every 
phase  of  the  subject,  from  the  selection  of  the  raw  materials  and  the 
proportioning  of  the  mix  to  the  valuation  of  the  finished  product.  In 
later  chapters  the  basis  and  determination  of  the  Cementation  Index 
will  be  found  discussed  in  detail.  In  the  present  chapter  it  is  only 
necessary  to  state  that  its  value  is  obtained  from  the  following  formula: 

(2. 8 X  percentage  silica)  -'- 
(l.lX percentage  alumina) -}- 

T    ,  .7X  percentage  iron  oxide 

Cementation  Index  =  =r r —  — . 

Percentage  lime  (CaO)  +1.4  percentage  magnesia 

This  formula  is  applicable  to  raw  materials  as  well  as  to  cements, 
but  the  user  must  recollect  that  the  first  factor  in  the  divisor  is  based 
on  the  percentage  of  lime  (CaO),  not  of  lime  carbonate  (CaCOs),  and 
similarly  with  the  magnesia. 

The  Cementation  Index,  determined  as  above  described,  is  a  meas- 
ure of  the  degree  of  basicity  of  a  cement,  or  the  relation  of  the  acid 
(SiO2,Al2O3,Fe2O3)  to  the  basic  (CaO,MgO)  factors  in  its  composition. 
A  high  cementation  index  means  a  high-limed  and  low-clayed  cement, 
while  a  low  index  would  mean  the  opposite.  In  Portland  cements 
as  at  present  made  the  Cementation  Index  will  commonly  fall  within 
the  limits  of  1.00  and  1.20,  1.00  being  the  ideal  index  for  a  Portland. 

Silica-alumina  ratio. — The  ratio  between  the  silica  and  the  alumina 
H-iron  oxide  gives  the  second '  important  index  to  the  character  of  a 
cement.  For  convenience  of  reference  this  may  be  termed  the  silica- 
alumina  ratio.  This  ratio,  properly  speaking,  should  take  into  account 
the  different  combining  weights  of  the  three  compounds  concerned, 
and  would,  therefore,  theoretically  be  found  from  the  formula 

.   . ,.,     -•  j  2. 8 X percentage  silica 

Acidity  Index  =  -— ; r  : r^ . 

( 1 . 1 X  percentage  alumina)  +  ( .  7  X  percentage  iron  oxide) 

To  the  value  determined  by  this  formula  the  term  "Acidity  Index7' 
might  be  very  properly  applied.  But  in  ordinary  practice  the  per- 
centage of  iron  oxide  present  is  so  small  that  the  ratio  between  the 
silica  and  the  alumina + iron  is  given  correctly  enough  by  simple 
division,  i.e., 

Percentage  silica       

Percentage  alumina + percentage  iron  oxide* 

The  value  thus  obtained  will  be  called  briefly  the  silica-alumina  ratio 
(though  it  considers  the  iron  oxide  also) .  It  may  be  said  that  the  per- 
centage of  lime  being  constant,  the  clinkering  temperature  decreases 


300  CEMENTS,  LIMES,  AND  PLASTERS. 

with  the  silica-alumina  ratio;  while  the  setting  -  time  and  ultimate 
strength  of  the  cement  are  in  inverse  proportion  to  the  values  of  the 
ratio. 

Kinds  of  material  used. — Before  taking  up  the  detailed  discussion 
of  the  various  raw  materials  used  in  the  manufacture  of  Portland  cement, 
some  general  statements  on  the  kinds  and  combinations  "of  raw  mate- 
rials actually  in  use  will  probably  be^  found  serviceable. 

In  order  that  the  value  and  availability  of  different  raw  materials 
may  be  estimated,  it  will  be  convenient  to  assume  a  certain  ideal  com- 
position for  a  cement  rock.  For  the  purposes  of  tljie  present  chapter 
this  can  be  done  in  a  sufficiently  accurate  way  by  considering  that 
a  Portland-cement  mixture,  when  ready  for  burning ,  should  contain 
about  75  per  cent  of  lime  carbonate  (CaC03),  and  about  20  per  cent  of 
silica  (Si02),  alumina  (A^Os),  and  iron  oxide  (Fe20s)  together,  the 
remaining  5  per  cent  or  so  containing  any  magnesia,  sulphur,  and  alkalies 
that  may  be  present.  More  exact  information  on  these  points  will 
be  found  in  Chapter  XXIX ,  where  a  somewhat  detailed  discussion  of 
the  calculation  and  composition  of  Portland-cement  mixtures,  together 
with  a  number  of  analyses  of  actual  mixtures  and  cements,  will  be 
given. 

The  essential  elements  which  enter  into  this  mixture — lime,  silica, 
alumina,  and  iron — are  all  abundantly  and  widely  distributed  in  nature, 
occurring  in  different  forms  in  many  kinds  of  rocks;  and  it  can  read- 
ily be  seen  that,  theoretically,  a  satisfactory  Portland-cement  mixture 
could  be  prepared  by  combining,  in  an  almost  infinite  number  of  ways 
and  proportions,  many  possible  raw  materials.  Obviously,  too,  we 
might  expect  to  find  perfect  gradations  in  the  degree  of  artificialness 
of  such  a  mixture,  varying  from  the  one  extreme  where  a  natural  rock 
of  almost  absolutely  correct  composition  was  used  to  the  other  extreme 
where  two  or  more  materials  in  nearly  equal  amounts  were  required 
to  produce  a  mixture  of  correct  composition. 

The  almost  infinite  number  of  raw  materials  which  are  theoretically 
available  are,  however,  reduced  to  a  very  few  in  practice  under  existing 
commercial  conditions.  The  necessity  for  producing  the  mixture  as 
cheaply  as  possible  rules  out  of  consideration  a  large  number  of  mate- 
rials which  would  be  considered  available  if  chemical  composition  was 
the  only  thing  to  be  taken  into  account.  Some  materials  otherwise 
suitable  are  too  scarce  and  consequently  too  expensive  for  such  use; 
some  are  too  difficult  to  pulverize  finely  and  bring  into  combination. 
In  consequence  comparatively  few  combinations  of  raw  materials  are 
actually  in  use. 


PORTLAND  CEMENT:  PRELIMINARY  STATEMENTS. 


301. 


In  certain  favored  localities  deposits  of  argillaceous  (clayey)  lime- 
stones or  " cement  rock"  have  been  found  in  which  the  lime,  silica,, 
alumina,  and  iron  oxide  exist  in  so  nearly  the  proper  proportions  that 
only  a  relatively  small  amount  (say  10  per  cent  or  so)  of  other  material, 
added  before  calcination,  is  required  in  order  to  make  a  mixture  of 
correct  composition.  Certain  blast-furnace  slags  are  also  close  in  com- 
position to  the  desired  mixture,  and  are  used  like  " cement  rock". 

In  the  majority  of  plants,  however,  most  or  all  of  the  necessary  lime 
is  furnished  by  one  raw  material,  while  the  silica,  alumina,  and  iron 
oxide  are  largely  or  entirely  derived  from  another  raw  material.  The 
raw  material  which  furnishes  the  lime  is  usually  a  natural  limestone — 
either  a  hard  limestone,  a  chalk,  or  a  marl — but  occasionally  an  artificial 
product  is  used,  such  as  the  chemically  precipitated  lime  carbonate 
which  results  as  a  waste  or  by-product  of  alkali  manufacture.  The 
silica,  alumina,  and  iron  oxide  of  the  mixture  are  usually  derived  from 
clays  or  shales,  more  rarely  from  slates. 

The  various  raw  materials  available  for  use  in  Portland-cement 
manufacture  differ  in  composition,  physical  characters,  and  origin.  As 
to  composition,  they  may  be  almost  (a)  purely  calcareous,  (6)  a  mixture 
of  calcareous  and  argillaceous  elements,  or  (c)  almost  purely  argilla- 
ceous; as  to  physical  characters  they  may  be  (a)  hard  and  massive, 
like  the  hard  limestones  and  slates,  (6)  soft,  like  the  chalks  and  shales,, 
or  (c)  granular  or  unconsolidated,  like  the  marls,  clays,  alkali  waste, 
and  granulated  slag.  As  to  origin,  they  may  be  (a)  natural,  like  lime- 
stones, marls,  slates,  clays,  etc.,  or  (6)  artificial,  like  alkali  waste  and 
furnace  slag. 

TABLE  144. 
CHARACTER  OF  PORTLAND-CEMENT  MATERIALS. 


Natural. 

Artificial. 

Hard. 

Soft. 

Unconsolidated. 

Unconsolidated. 

Calcareous 
(CaCO3  over  75%) 

Pure  hard 
limestone 

Pure  soft 
limestone  or 
pure  chalk 

Pure  marl 

Alkali  waste 

Argillo-calcareous 
(CaCO3  40  to  75%) 

Hard  clayey 
limestone 
(cement  rock) 

Soft  limestone 
or  clayey 
chalk 

Clayey  marl 

Blast-furnace 
slag 

Argillaceous 
(CaCOg    less    than 
40%) 

Slate 

Shale 

Clay 

302  CEMENTS,  LIMES,  AND   PLASTERS. 

A  glance  at  the  tabulation  above  will  show  the  relative  physical 
and  chemical  characters  of  the  different  raw  materials.  It  is  obvious, 
if  75  per  cent  of  lime  carbonate  will  make  a  good  cement  mixture, 
that  any  of  the  materials  in  the  middle  line  (i.e.;  the  Argillo-calcareous 
group)  could  be  used  as  a  basis  and  its  composition  corrected  by  adding 
either  a  purely  calcareous  material  or  a  purely  argillaceous  material, 
as  might  be  necessary.  The  cement  practice  in  the  Lehigh  district  is 
an  example  of  this  kind  of  mixing.  But  the  same  result  could  be  ob- 
tained by  mixing  any  one  of  the  materials  on  the  first  line  of  the 
table  (i.e.,  the  Calcareous  group)  with  any  one  of  the  argillaceous  mate- 
rials listed  in  the  bottom  line.  This  is  the  method  followed  at  most  plants 
outside  of  the  Lehigh  district.  There  is  really  little  to  choose  between 
the  two  kinds  of  mixtures,  for  the  final  result  is  the  main  thing.  In  later 
pages  the  few  differences  that  do  exist  are  pointed  out  and  the  advan- 
tages and  disadvantages  of  each  type  are  mentioned. 

In  previous  papers  the  writer  has  grouped,  under  six-  heads,  the 
various  combinations  of  raw  materials  at  present  used  in  the  Ignited 
States  in  the  manufacture  of  Portland  cement.  This  grouping  is  as 
follows : 

(1)  Argillaceous  hard  limestone  (cement  rock)  and  pure  limestone. 

(2)  Pure  hard  limestone  and  clay  (or  shale). 

(3)  Soft  (chalky)  limestone  and  clay  (or  shale). 

(4)  Marl  and  clay  (or  shale). 

(5)  Alkali  waste  and  clay. 

(6)  Slag  and  pure  limestone. 

The  relative  commercial  importance  of  these  different  combinations 
is  indicated  by  the  figures  tabulated  on  page  304. 

Examination  of  the  statistics  there  given,  which  have  been  arranged 
by  the  writer  from  figures  given  in  the  various  volumes  on  ' '  Mineral  Re- 
sources of  the  United  States",  issued  by  the  U.  S.  Geological  Survey, 
will  develop  several  facts  of  interest.  In  the  first  place  it  will  be  seen 
that  the  "cement-rock"  type  of  mixture,  important  because  of  its 
use  in  the  Lehigh  district,  is  slowly  decreasing  in  relative  importance, 
having  fallen  from  almost  three  fourths  of  the  total  product  in  1898  to 
only  a  little  over  half  the  total  product  in  1903.  In  absolute  number 
of  barrels  produced  per  year,  it  is  of  course  rapidly  increasing,  but  it 
is  no  longer  the  only  type  of  material  to  be  considered. 

The  use  of  marl  as  a  cement  material  is  also  slowly  decreasing  in 
relative  importance,  having  reached  its  point  of  maximum  output  in 
1899,  when  it  supplied  almost  one  fifth  of  all  the  cement  made.  The 
hard  limestones,  on  the  other  hand,  have  increased  steadily  in  importance 


PORTLAND   CEMENT:  PRELIMINARY  STATEMENTS.  303 

'100 


80 


60 


40 


Cement, 


\ 


FIG.  64. — Percentage  of  total  output  produced  from  different  raw  materials. 


304 


CEMENTS,  LIMES,  AND   PLASTERS. 


-TABLE  145. 

PRODUCTION  OF  PORTLAND  CEMENT  FROM  VARIOUS  MATERIALS. 


Type  1. 

Type  2.* 

Type  3. 

Type  4.f 

Argillaceous 
Limestone 
(Cement  Rock) 

Marl  and  Clay. 

Soft  Limestone 
(Chalk)  and  Clay. 

Hard  Limestone 
and  Clay. 

Year. 

and  Pure  Limestone. 

Per 

Per 

* 

Per 

Per 

Barrels. 

Cent 
of 

Barrels. 

Cent 
of 

Barrels. 

Cent 
of 

Barrels. 

Cent 
of 

Total. 

Total. 

Total. 

Total. 

1898 

2,682,304 

74.9 

545,372 

15.2 

39,000 

1.1 

315,608 

8.8 

1899 

4,010,132 

70.9 

1,095,934 

19.4 

88,200 

1.6 

458,000 

8.1 

1900 

5,919,629 

70.3 

1,444,797 

17.1 

184,400 

2:  -2 

874,715 

10.4 

1901 

8,503,500 

66.8 

2,001,200 

15.8 

495,752 

3.9 

1,710,773 

13.5 

1902 

10,923,922 

63.6 

2,214,519 

12.9 

372,413 

2.2 

3,673,790 

21.3 

1903 

12,493,694 

55.7 

3,052,946 

13.6 

457,813 

2.4 

6,338,520 

28.3 

*  Including  also  the  product  from  alkali  waste  and  clay0 
t  Including  also  the  product  from  slag  and  limestone. 

from  1898,  when  they  produced  less  than  one  tenth  of  the  total  output, 
to  1903,  when  they  produced  almost  three  tenths.  The  soft  chalky 
limestones  show  little  increase  and  are  still  unimportant  producers, 
though  the  writer  believes  that  they  offer  brilliant  possibilities. 

Valuation  of  Deposits  of  Cement  Materials. 

Determining  the  possible  value  for  Portland-cement  manufacture 
of  a  deposit  of  raw  material  is  a  complex  problem,  depending  upon  a 
number  of  distinct  factors,  all  of  which  must  be  given  due  consideration. 
The  more  important  of  these  factors  are: 

1.  Chemical  composition  of  the  material. 

2.  Physical  character  of  the  material. 

3.  Amount  of  material  available. 

4.  Location  of  the  deposit  with  respect  to  transportation  routes. 

5.  Location  of  the  deposit  with  respect  to  fuel  supplies. 

6.  Location  of  the  deposit  with  respect  to  markets. 
Ignorance  of  the  respective  importance  of  these  factors  frequently 

leads  to  an  overestimate  of  the  value  of  a  deposit  of  raw  material.  Their 
effects  may  be  briefly  stated  as  follows: 

1.  Chemical  composition. — The  raw  material  must  be  of  correct 
chemical  composition  for  use  as  a  cement  material.  This  implies  that 
the  material,  if  a  limestone,  must  contain  as  small  a  percentage  as  possi- 
ble of  magnesium  carbonate.  Under  present  conditions  5  or  6  per  cent 
is  the  maximum  permissible.  Free  silica  in  the  form  of  chert,  flint, 


PORTLAND  CEMENT:  PRELIMINARY  STATEMENTS.  305 

or  sand  must  be  absent,  or  present  only  in  small  quantities — say  1  per 
cent  or  less.  If  the  limestone  is  a  clayey  limestone,  or  "cement  rock", 
the  proportion  between  its  silica  and  its  alumina  and  iron  should  pref- 
erably fall  within  the  limits 


Al2O3  +  Fe2O3        •AljsO3  +  Fe2O3 

A  clay  or  shale  should  satisfy  the  above  equation,  and  should  be  free 
from  sand,  gravel,  etc.  Alkalies,  sulphides,  and  sulphates  should,  if 
present,  not  exceed  3  per  cent  or  so. 

2.  Physical  character. — Economy   in  excavation   and   crushing  re- 
quires that  the  raw  materials  should  be  as  soft  and  as  dry  as  possible. 

3.  Amount  available. — A  Portland-cement  plant  running  on  dry  raw 
materials,  such  as  a  mixture  of  limestone  and  shale,  will  use  approxi- 
mately 20,000  tons  of  raw  material  per  year  per  kiln.     Of  this  about 
15,000  tons   are  limestone  and  5000  tons  shale.      Assuming  that  the 
limestone  weighs  160  Ibs.  per  cubic  foot,  which  is  a  fair  average  weight, 
each  kiln  in  the  plant  will  require  about  190,000  cubic  feet  of  limestone 
per  year.     As  the  shale  or  clay  may  be  assumed  to  contain  considerable 
water,  a  cubic  foot  will  probably  contain  not  over  125  Ibs.  of  dry  mate- 
rial, so  that  each  kiln  will  also  require  about  80,000  cubic  feet  of  shale 
or  clay. 

A  cement-plant  is  an  expensive  undertaking,  and  it  would  be  folly 
to  locate  a  plant  with  less  than  a  twenty  years'  supply  of  raw  material 
in  sight.  This  would  require  that,  to  justify  the  erection  of  a  cement- 
plant  on  any  property, 

For  each  kiln  of  the  proposed  plant,  there  must  be  in  sight  at  least 
3 ,800 flOO  cubic  feet  of  limestone  and  1, 600 pOO  cubic  feet  of  clay  or  shale. 

4.  Location  with  respect  to  transportation  routes. — Portland  cement 
is,  for  its  value,  a  bulky  product,  and  is  therefore  much  influenced  by 
the  subject  of  transportation  routes.     To  locate  a  plant  on  only  one 
railroad,  unless  the  railroad  officials  are  financially  connected  with  the 
cement-plant,  is  simply  to  invite  disaster.     At  least  two  transportation 
routes  should  be  available,  and  it  is  best  of  all  if  one  of  these  be  a  good 
water  route. 

5.  Location  with  respect  to  fuel  supplies. — Every  barrel  (380  Ibs.) 
of  Portland  cement  marketed  implies  that  at  least  200  to  300  Ibs.  of 
coal  have  been  used  in  the  power-plant  and  the  kilns.     In  other  words, 
each  kiln  in  the  plant  will,  with  its  corresponding  crushing  machinery, 
use  up  from  6000  to  9000  tons  of  coal  per  year.     The  item  of  fuel  cost 
is  therefore  highly  important,  for  in  the  average  plant  about  30  to  40 


306  CEMENTS,  LIMES,  AND  PLASTERS. 

per  cent  of  the  total  cost  of  the  cement  will  be  chargeable  to  coal  sup- 
plies. 

6.  Location  with  respect  to  markets. — In  order  to  secure  an  estab- 
lished position  in  the  trade,  a  new  cement-plant  should  have  (a)  a  local 
market  area,  within  which  it  may  sell  practically  on  a  non-competitive 
basis,  and  (6)  easy  access  to  a  larger  though  competitive  market  area. 

All  of  these  factors  should  receive  due  consideration  in  deciding  on 
the  erection  of  a  cement-plant.  The  summary  just  given  is  merely 
in  the  nature  of  a  preliminary  note,  for  these  points  are  taken  up  in 
more  detail  in  later  chapters,  particularly  in  those  devoted  to  the  vari- 
ous raw  materials  and  to  the  costs  of  manufacture.  The  prospecting, 
examining,  and  sampling  of  deposits  of  limestones,  marls,  clays,  and 
shales  will  be  taken  up  in  the  chapters  immediately  following. 


CHAPTER  XXIII. 
LIMESTONES. 

THE  Portland-cement  materials  which  are  discussed  in  this  and  the 
following  chapters  (XXIV,  XXV)  under  the  names  of  pure  hard  lime- 
stone, chalk,  argillaceous  limestone,  or  " cement  rock",  and  marl,  agree 
in  that  they  are  all  forms  of  limestones,  though  they  differ  sufficiently 
in  their  physical,  chemical,  and  economic  characters  to  be  discussed 
separately  and  under  different  names.  In  order  to  avoid  unnecessary 
repetition,  no  general  discussion  of  limestone  will  be  presented  here, 
but  reference  should  be  made  to  Chapter  VI,  where  the  origin,  varie- 
ties, composition,  and  properties  of  limestones  are  described  in  detail. 
In  the  present  chapter  these  general  facts  will  be  briefly  summarized, 
and  certain  features  common  to  all  the  types  of  limestone  used  in  Port- 
land-cement manufacture  will  be  noted,  after  which  these  different 
types  will  be  separately  discussed. 

Limestones  in  General. 

Varieties  and  origin. — Limestones  are  rocks  composed  largely  or 
entirely  of  lime  carbonate,  or  of  lime  carbonate  with  magnesium  carbo- 
nate. Though  one  or  both  of  these  carbonates  will  necessarily  be  the 
principal  ingredients  in  the  rock,  various  impurities  may.  occur.  In 
addition  to  the  chemical  differences  which  are  thus  caused  between 
different  samples  or  kinds  of  limestone,  they  may  also  differ  in  their 
physical  characters,  or  in  their  methods  of  origin,  or  in  both  of  these 
points. 

Limestones  are  primarily  formed  by  the  deposition  of  lime. carbonate 
from  sea-  or  lake- water  which  carries  this  salt  in  solution.  This  deposi- 
tion may  be  direct,  caused  by  chemical  processes,  or  it  may  be  effected 
through  the  agency  of  living  organisms.  Travertine  and  tufa  are  chem- 
ically deposited  limestones  formed  by  surface  waters.  Molluscs  are  able 
to  abstract  lime  carbonate  from  sea-water  and  utilize  it  in  the*  forma- 
tion of  tV>pir  shells.  On  the  death  ^  the  animals.. these  shells  sink  to 

307 


308  CEMENTS,  LIMES,  AND  PLASTERS. 

the  sea-bottom  and  thus  aid  in  the  formation  of  calcareous  deposits. 
Microscopic  organisms  acting  in  this  way  are  the  cause  of  the  forma- 
tion of  chalk,  as  noted  later  (p.  318).  Vegetable  life,  acting  in  a  more 
indirect  way,  appears  to  be  an  important  agency  in  the  deposition  of 
•mar/  (p.  338)..  Ordinary  limestones  may  have  originated  in  any  of 
the  ways  noted  above.  After  their  formation,  if  subjected  to  sufficient 
heat  and  pressure,  normal  limestones  ,-*nay  be  converted  into  crystalline 
limestones  or  marbles. 

All  the  varieties  of  limestone  above  named  may  vary  in  composition 
and  degree  of  purity  within  wide  limits.  ». 

Composition  of  limestones. — The  term  limestone  is  used,  in  its  most 
general  sense,  to  include  all  rocks  composed  largely  or  entirely  of  lime 
carbonate,  or  of  lime  carbonate  plus  magnesium  carbonate.*  A  limestone 
of  ideal  purity  will  of  course  consist  of  100  per  cent  of  these  carbonates; 
but  few  limestones  attain  even  approximate  purity  and  many  are  very 
impure.  As  the  percentage  of  impurities  increases,  the  limestone 
becomes  more  and  more  clayey  or  sandy  or  shaly,  until  at  last  the  name 
limestone  is  no  longer  applicable.  The  exact  lower  limit  of  the  group 
it  would  be  difficult  to  fix,  because  the  change  is  gradual,  but  probably 
all  would  agree  that  a  rock  containing  less  than  50  per  cent  of  carbonates 
can  hardly  be  called  a  limestone,  but  should  rather  be  termed  a  cal- 
careous clay  or  sandstone  or  shale,  as  the  case  may  be.  In  the  present 
volume,  therefore,  the  lower  limit  in  composition  of  limestones  will  be 
accepted  as  that  above  noted — i.e.,  50  per  cent  of  carbonates. 

As  the  average  composition  of  a  good  Portland -cement  mixture  is 
about  three  fourths  lime  carbonate  and  one  fourth  clayey  matter,  it 
is  obvious  that  such  a  composition  could  be  secured  either  by  mixing 
a  pure  limestone  and  a  pure  clay  in  the  proportions  of  about  three  parts 
limestone  and  one  part  clay,  or  by  starting  with  a  clayey  limestone 
carrying,  say,  60  to  85  per  cent  lime  carbonate  and  adding  enough  clay 
or  pure  limestone  to  bring  this  percentage  up  or  down  to  the  required 
75  per  cent.  The  " cement  rock"  of  the  Lehigh  district  is  an  example 
of  a  highly  argillaceous  limestone,  usually  too  low  in  lime  carbonate  to 
be  a  good  Portland-cement  material  of  itself  and  requiring  the  addi- 

*  When  discussing  Portland-cement  materials,  the  term  "limestone"  may  be 
still  further  restricted  so  as  to  entirely  exclude  the  highly  magnesian  limestones. 
At  present  all  the  Portland  cement  made  is  kept  as  low  in  magnesia  as  possible, 
because  of  the  fear  that  this  ingredient  may  do  some  harm  to  the  cement.  As  a 
cement  carrying  over  4  per  cent  of  magnesia  (MgO)  would  be  hard  to  market,  a 
limestone  carrying  over  6  to  8  per  cent  of  magnesium  carbonate  (MgCO3)  can 
hardly  be  classed  as  a  possible  Portland-cement  material  at  present. 


LIMESTONES.-  <-  309 

tion  of  a  relatively  small  percentage  of  pure  limestone.  At  a  few  Lehigh 
district  quarries,  however,  the  " cement  rock7'  is  a  little  too  high  in 
carbonate,  rather  than  too  low,  so  that  it  requires  the  addition  of  clay 
and  not  of  limestone. 

In  the  present  volume  the  term  " cement  rock"  will  be  used  to  cover 
clayey  limestones  low  in  magnesia  and  carrying  from  50  to  80  per 
cent  or  so  of  lime  carbonate,  while  limestones  higher  than  80  per  cent 
in  carbonate  will  be  called  for  convenience  "pure  limestones". 

Impurities  of  limestone. — Whether  a  limestone  consists  entirely 
of  calcium  carbonate  or  carries  more  or  less  of  magnesium  carbonate 
in  addition,  it  may  also  contain  a  greater  or  lesser  amount  of  distinct 
impurities.  From  the  point  of  view  of  the  Portland-cement  manu- 
facturer, the  more  important  of  these  impurities  are  silica,  alumina, 
iron,  alkalies,  and  sulphur,  all  of  which  have  a  marked  effect  on  the 
value  of  the  limestone  as  a  cement  material.  These  impurities  will 
therefore  be  discussed  in  the  order  in  which  they  are  named  above. 

The  silica  in  a  limestone  may  occur  either  in  combination  with 
alumina  as  a  clayey  impurity  or  not  combined  with  alumina.  As 
the  effect  on  the  value  of  the  limestone  would  be  very  different  in 
the  two  cases,  they  will  be  taken  up  separately. 

Silica  alone. — Silica,  when  present  in  a  limestone  containing  no 
alumina,  may  occur  in  one  of  three  forms,  and  the  form  in  which  it 
occurs  is  of  great  importance  in  connection  with  cement -manufacture. 

(1)  In  perhaps  its  commonest  form,   silica  is  present  in  nodules, 
masses,  or  beds  of  flint  or  chert.     Silica  occurring  in  this  form  will  not 
readily  enter  into  combination  with  the  lime  of  a  cement  mixture,  and 
a  cherty  or  flinty  limestone  is  therefore  almost  useless  in  cement-manu- 
facture. 

(2)  In  a  few  cases,  as  in  the  hydraulic  limestone  of  Teil,  France, 
a  large  amount  of  silica  is  present  and  very  little  alumina,  notwith- 
standing which  the  silica  readily  combines  with  the  lime  on  burning. 
It  is  probable  that  in  such  cases  the  silica  is  present  in  the  limestone 
in  a  very  finely  divided  condition,  or  possibly  as  hydrated  silica,  pos- 
sibly as  the  result  of  chemical  precipitation  or  of  organic  action.     In 
the  majority  of  cases,  however,  a  highly  siliceous  limestone  will  not  make 
a  cement  on  burning  unless  it  contains  alumina  in  addition  to  the  silica. 

(3)  In  the  crystalline  limestones  (marbles)  and  less  commonly  in 
uncrystalline  limestones,  whatever  silica  is  present  may  occur  as  a  com- 
plex silicate  in  the  form  of  shreds  of  mica,  hornblende,  or  other  sili- 
cate mineral.     In  this  form  silica  is  somewhat  intractable  in  the  kiln 
and  mica  and  other  silicate  minerals  are  therefore  to  be  regarded   as 


310  CEMENTS,  LIMES,  AND  PLASTERS. 

inert  and  useless  impurities  in  a  cement  rock.  These  silicates  will  flux 
at  a  lower  temperature  than  pure  silica  and  are  thus  not  so  trouble- 
some as  flint  or  chert.  They  are,  however,  much  less  serviceable  than 
if  the  same  amount  of  silica  were  present  in  combination  with  alumina 
as  a  clay. 

Silica  with  alumina. — Silica  and  alumina,  combined  in  the  form 
of  clay,  are  common  impurities,  in  limestones,  and  are  of  special  inter- 
est to  the  cement  manufacturer.  The  best-known  example  of  such 
an  argillaceous  limestone  is  the  cement  rock  of  the  Lehigh  district  of 
Pennsylvania.  Silica  and  alumina,  when  present  jn  this  combined 
form,  combine  readily  with  the  lime  under  the  action  of  heat,  and  an 
argillaceous  limestone  therefore  forms  an  excellent  basis  for  a  Port- 
land-cement mixture. 

Iron. — Iron  when  present  in  a  limestone  occurs  commonly  as  the 
oxide  (Fe203)  or  sulphide  (FeS2);  more  rarely  as  iron  carbonate  or 
in  complex  silicate.  Iron  in  the  oxide,  carbonate,  or  silicate  forms 
is  a  useful  flux,  aiding  in  the  combination  of  the  lime  and  silica  in  the 
kiln.  When  present  as  a  sulphide  in  the  form  of  the  mineral  pyrite 
it  is  to  be  avoided  in  quantities  over  2  or  3  per  cent. 

Alkalies. — Soda  and  potash  occur  usually  in  small  percentages 
and  most  commonly  in  the  looser-textured  limestones.  It  is  probable 
that  these  alkalies  are  largely  driven  off  in  the  kiln,  so  that  they  do  no 
particular  harm  to  the  cement.  If  the  total  amount  of  alkalies  is  above 
5  per  cent,  however,  a  sufficient  amount  will  be  carried  over  into  the 
cement  to  cause  trouble;  and  raw  materials  carrying  more  than  5  per 
cent  of  soda  and  potash  together  should  therefore  be  looked  upon  with 
suspicion,  if  not  absolutely  rejected. 

Sulphur. — Sulphur  may  occur  combined  with  lime  as  lime  sulphate, 
or  combined  with  iron  as  the  mineral  pyrite.  In  either  case  it  is  an 
injurious  impurity,  and  the  presence  of  over  1  to  li  per  cent  of  total 
sulphur  should  cause  the  rejection  of  the  raw  material. 

Physical  characters  of  limestones. — In  texture,  hardness,  and  com- 
pactness the  limestones  vary  from  the  loosely  consolidated  marls 
through  the  chalks  to  the  hard,  compact  limestones  and  marbles.  Paral- 
lel with  these  variations  are  variations  in  absorptive  properties  and 
density.  The  chalky  limestones  may  run  as  low  in  specific  gravity  as 
1.85,  corresponding  to  a  weight  of,  say,  110  Ibs.  per  cubic  foot,  while 
the  compact  limestones  commonly  used  for  building  purposes  range 
in  specific  gravity  between  2.3  and  2.9;  corresponding  approximately 
to  a  range  in  weight  of  from  140  to  185  Ibs.  per  cubic  foot. 

From  the  point  of  view  of  the  Portland-cement  manufacturer  these 


LIMESTONES. 


311 


variations  in  physical  properties  are  of  economic  interest  chiefly  in 
their  bearing  upon  two  points:  the  percentage  of  water  carried  by 
the  limestone  as  quarried,  and  the  ease  with  which  the  rock  may  be 
crushed  and  pulverized.  To  some  extent  the  two  properties  counter- 
balance each  other,  for  the  softer  the  limestone  the  more  absorbent 
it  is  likely  to  be.  These  purely  economic  features  will  be  discussed  in 
more  detail  in  later  chapters. 

Effect  of  heating  on  limestone. — On  heating  a  non-magnesian  lime- 
stone to  or  above  750°  F.,  its  carbon  dioxide  will  be  driven  off,  leav- 
ing quicklime  (calcium  oxide,  CaO).  If  a  magnesian  limestone  be  simi- 
larly treated,  the  product  would  be  a  mixture  of  calcium  oxide  and 
magnesium  oxide  (MgO).  The  rapidity  and  perfection  of  this  decom- 
position can  be  increased  by  passing  steam  or  air  through  the  burning 
mass.  In  practice  this  is  accomplished  either  by  the  direct  injection 
of  air  or  steam,  or  more  simply  by  thoroughly  wetting  the  limestone 
before  putting  it  into  the  kiln. 


FIG.  65. — Working  thick. limestone-bed. 

If,  however,  the  limestone  contains  an  appreciable  amount  of  silica, 
alumina,  and  iron,  the  effects  of  heat  will  not  be  of  so  simple  a  char- 
acter. At  temperatures  of  800°  C.  and  upwards  these  clayey  impuri- 
ties will  combine  with  the  lime  oxide,  giving  silicates,  alummates,  and 


312  CEMENTS,  LIMES,  AND  PLASTERS. 

related  salts  of  lime.  In  this  manner  a  natural  cement  will  be  pro- 
duced. An  artificial  mixture  of  certain  and  uniform  composition 
burned  at  a  higher  temperature  will  give  a  Portland  cement  the  details 
of  whose  manufacture  are  discussed  in  the  present  section  of  this 

book. 

Pure  Hard  Limestones. 

Under  this  heading  are  grouped  limestones  of  normal  hardness  (ex- 
cluding the  soft  chalky  limestones  and  the  marls)  which  carry  no  less 
than  80  per  cent  of  lime  carbonate  and  less  than  6  per  cent  of  magne- 
sium carbonate.  Limestones  carrying  less  than  80  per  cent  of  lime 
carbonate  are  described  in  the  next  chapter  under  the  heading  of  Cement 
Rock.  The  boundary  between  the  two  classes  is  of  course  an  arbitrary 
limit,  and  80  per  cent  of  CaCOs  has  been  selected  for  convenience.  As 
a  matter  of  fact,  most  of  the  limestones  used  in  cement-plants  are  much 
purer  than  the  lower  limit  above  fixed,  ranging  usually  from  90  to  95 
per  cent  of  lime  carbonate. 

Soon  after  the  American  Portland-cement  industry  had  become 
fairly  well  established  in  the  Lehigh  district,  attempts  were  made  in 
New  York  State  to  manufacture  Portland  cement  from  a  mixture  of 
pure  limestone  and  clay.  These  attempts  were  not  commercially  suc- 
cessful, and  although  their  lack  of  success  was  not  due  to  any  defects 
in  the  limestone  used,  a  certain  prejudice  arose  against  the  use  of  the 
hard  limestones.  In  recent  years,  however,  this  has  disappeared,  and 
a  very  large  proportion  of  the'  American  output  is  now  made  from  mix- 
tures of  limestone  with  clay  or  shale.  (See  page  304  for  comparative 
figures.)  This  reestablishment  in  favor  of  the  hard  limestone  is  doubtless 
due  in  great  part  to  recent  improvements  in  grinding  machinery,  for 
the  purer  limestones  are  usually  much  harder  than  argillaceous  lime- 
stones like  the  Lehigh  district  "cement  rock". 

Composition  of  hard  limestones  actually  used. — In  Table  146  analyses 
of  a  large  number  of  limestones  used  at  American  cement-plants  are 
given.  On  examination  it  will  be  seen  that  most  of  these  limestones 
range  from  49  to  54  per  cent  of  lime  (CaO)  and  thus  represent  quite 
pure  rocks,  since  a  theoretically  pure  limestone  composed  entirely  of 
lime  carbonate  (CaCOs)  will  contain  only  56  per  cent  of  lime  (CaO),  the 
remaining  44  per  cent  being  carbon  dioxide  (C02).  With  few  excep- 
tions the  limestones  analyzed  carry  less  than  1  per  cent  of  magnesia 
(MgO).  Their  sulphur  percentages  are  also  low,  which  appears  to  be 
more  commonly  the  case  in  dealing  with  a  hard  limestone  than  when 
a  soft  limestone  or  marl  is  in  question.  The  same  may  be  said  in  regard 
;to  alkalies. 


LIMESTONES.  313 

In  prospectuses  and  in  the  reports  of  "cement  experts",  analyses 
of  limestones  averaging  98  or  99  per  cent  of  lime  carbonate  are  quite 
common,  but  in  real  life  a  quarry  that  will  steadily  turn  out  limestone 
94  per  cent  pure  is  about  as  good  as  can  be  hoped  for.  With  a  lime- 
stone of  this  degree  of  purity  little  attention  need  be  paid  to  the  char- 
acter of  the  remaining  6  per  cent  of  impurities.  But  when  a  limestone 
carrying  90  per  cent  or  less  of  lime  carbonate  (equivalent  to  about  50 
per  cent  of  lime)  is  in  use  or  under  consideration,  the  character  of  the 
impurities  becomes  of  the  first  importance. 

Of  course  objectionable  percentages,  of  sulphur  compounds  or  mag- 
nesia would  be  enough  to  debar  a  limestone  from  use,  but  even  when  the 
impurity  consists  of  clayey  matter  (silica,  alumina,  and  iron  oxide)  its 
exact  composition  is  a  matter  of  importance  and  should  be  carefully 
studied.  The  matter  of  interest  is  the  ratio  given  for  the  formula 

Percentage  silica  (SiO2) 
Percentage  alumina  (A12O3)  +  percentage  iron  oxide  (Fe2O3)' 

It  is  to  be  noted  that  the  importance  of  this  question  increases  as 
the  limestone  becomes  less  pure.  The  reason  for  this  is  obvious.  Sup- 
pose we  are  dealing  with  two  limestones  of  respective  composition: 

A.  B. 

Lime  carbonate 95 . 00  80 . 00 

Silica 4.00  16.00 

Alumina 0 . 70  2 . 80 

Iron  oxide 0 .30  1 .20 

The  ratio  •    .     ^ — -r-  will  in  each  case  give  a  value  of  4.0;    but 

Al2O3  +  Fe2O3 

the  result  to  the  cement  manufacturer  will  be  very  different.  If  he 
uses  limestone  A,  its  silica-alumina  ratio  is  of  little  importance,  for 
as  the  limestone  is  very  pure  (95  per  cent  CaCOa)  it  will  require  the  addi- 
tion of  considerable  clay.  The  silica-alumina  ratio  of  the  mix  will  there- 
fore be  determined  by  that  of  the  clay,  not  by  the  ratio  shown  by  the 
limestone;  and  the  manufacturer  can  select  a  clay  which  will  give  what- 
ever he  considers  a  desirable  ratio  for  the  mix. 

But  if  he  should  use  limestone  B,  it  would  require  but  little  clay, 
since  it  is  already  very  clayey;  and  it  would  be  almost  impossible  to 

find   a   clay   sufficiently   aluminous   to   reduce   the  77-^- T?~~FT  ratio 

A12(J3  +  -b  e2(J3 

much  below  the  4.0  which  is  fixed  by  the  limestone. 

For  this  reason  it  may  be  taken  as  a  safe  rule  that  when  a  limestone 


314 


CEMENTS,  LIMES,  AND  PLASTERS. 


TABLE  146. 
ANALYSES  OF  HARD  LIMESTONES  USED  AT  AMERICAN  CEMENT-PLANTS. 


Silica 
(Si02). 

Alumina 
(A1203). 

Iron 
oxide 
(Fe203). 

Lime 
(CaO). 

Magnesia 
(MgO). 

Sulphur 
trioxide 
(S03). 

Carbon 
dioxide 
(C02). 

Water. 

1 

1.21 

0.70 

0.50 

53  .  62  -T 

0.44 

0.11 

42.98 

2 

0.98 

0.58 

0.34 

54.17 

0.13 

0.21 

42.96 

3 

1.02 

1.91 

53.36 

0.39 

0.12 

43.01 

4 

1.93 

2.37 

53.15 

tr. 

n.d. 

42.46 

5 

1.46 

2.15 

53.62 

tr. 

n.  d. 

42.85 

6 

2.12 

0.28 

0.50 

54.06 

0.77 

n.  d. 

42.34 

7 

6.06 

3.92 

49.46 

0.91 

0.10 

39.06 

8 

8.20 

1.30 

49.37 

0.85 

n.  d. 

39.72 

9 

7.54 

3.43 

45.57 

4.36 

.... 

39.57 

10 

5.06 

'    2.32 

48.29 

3.66 

.... 

41.05 

11 

13.89 

2.61 

45.91 

1.00 

.... 

36.82 

12 

5.43 

1.43 

52.02 

1.11 

.... 

40.24 

13 

0.74 

0.13 

52.49 

1.87 

.... 

43.68 

14 

0.89 

0.38 

0.25 

54.48 

0.36 

.... 

43.40 

15 

0.87 

0.34 

0.13 

54.68 

0.32 

.... 

43.44 

16 

0.86 

0.29 

55.74 

0.51 

42.76 

0.04 

17 

1.00 

0.9 

2.0 

51.10 

1.4 

.... 

43.5 

18 

1.19 

0.95 

1.28 

53.13 

1.36 

tr." 

42.66 

19 

1.1 

1.8 

51.7 

2.0 

0.1 

43.3 

20 

0.83 

1.07 

52.67 

1.67 

.... 

43.19 

21 

1.54 

2.06 

52.85 

0.65 

.... 

42.23 

22 

4.17 

1.37 

49.34 

2.94 

.... 

41.94 

23 

0.95 

0.50 

53.94 

0.91 

.... 

43.38 

24 

3.12 

1.15 

52.06 

1.07 

.... 

42.06 

25 

0.40 

0.44 

54.87 

0.20 

.... 

43.34 

26 

0.54 

0.42 

54.73 

0.19 

.... 

43.22 

27 

0.24 

0.38 

55.46 

0.26 

.... 

43.86 

28 

1.54 

0.39 

1.04 

53.87 

0.52 

.... 

29 

3.12 

0.93 

52.58 

0.80 

6^24 

42.17 

30 

2.70 

1.64 

52.18 

1.28 

0.17 

42.39 

31 

9.72 

4.20         0.48 

47.11 

0.66 

32 

6.30 

3.35 

50.25 

0.22 

33 

7.88 

4.01 

48.10 

0.53 

34 

3.30 

1.30 

52.15 

1.58 

0.30 

40.98 

35 

0.06 

0.63          1.03 

53.86 

.... 

.... 

43.20 

36 

3.53 

1.14 

54.45 

6^44 

38.74 

37 

4.20 

1.61 

1.90 

50  .  66 

0.73 

6^23 

40.60 

38 

1.30 

0.73 

1.17 

53.34 

0.75 

0.03 

42.72 

39 

9.46 

2.45 

2.73 

45.70 

0.99 

1.36 

36.98 

40 

0.56 

1.23 

0.29 

54.45 

0.36 

tr. 

43.17 

41 

4.50 

0.20 

1.77 

49.31 

0.75 

0.06 

40.54 

2.59 

42 

4.14 

0.21 

1.77 

50.16 

0.42 

0.20 

39.87 

2.03 

43 

2.31 

0.24 

1.18 

52.04 

0.43 

0.17 

41.72 

1.65 

44 

5.52 

2.97 

49.66 

0.78 

45 

n.  d. 

n.  d. 

n.  d. 

54.3 

0.7 



43.63 

1-5.  Pacific  P.  C.  Co.,  Suisun,  Calif.     C.  J.  Wheeler,  analyst. 

6.  Southern  States  P.  C.  Co.,  Rockmart,  Ca.     J.  F.  Davis,  analyst. 

7.  Chicago  P.  C.  Co.,  Oglesby,  111.     Quoted  in  manufacturers'  circular. 

8.  Marquette  C.  Co.,  Oglesby,  111.     20th  Ann.  Rep.  U.  S.  G.  S.,  pt.  6,  p.  544. 
9-12.  German-American  P.  C.  Works,  La  Salle,  111.     W.  E.  Pressing,  analyst. 

13.  Lehigh  P.  C.  Co.,  Mitchell,  Ind.     F.  W.  Clarke,  analyst. 


LIMESTONES. 


315 


carries  less  than  90  per  cent  of  lime  carbonate  it  should  give  a  value 

Si02 


of  between  2.25  and  3.0  for  the  ratio 


These  are  comfort- 


able  limits,  and  will  give  the  manufacturer  considerable  latitude  in  his 
choice  of  a  clay  to  mix  with  it. 


FIG.  66. — Working  heavy  horizontal  bed  of  limestone. 

Prospecting  and  examining  limestone  deposits. — The  prospector 
looking  for  a  deposit  of  good  limestone,  or  the  engineer  engaged  to 
report  on  a  deposit  already  located,  should  both  realize  that  much 
trouble  can  be  avoided  if  they  will  first  familiarize  themselves  with 


14-15.  Bedford  P.  C.  Co.,  Bedford,  Ind.     A.  W.  Smith,  analyst.     20th  Ann.  Rep.  U.  S.  GeoL 
Survey,  pt.  6,  p.  381. 

16.  Tola  P.  C.  Co.,  Tola,  Kansas.     H.  N.  Stokes,  analyst.     Bull.  78,  U.  S.  Geol.  Survey,  p.  124. 
17  -18.   Tola  P.  C.  Co.,  lola.  Kansas. 

19.  Kansas  P.  C.  Co.,  lola,  Kansas. 
20  -24.  Alpena  P.  C.  Co.,  Alpena,  Mich. 
25-26.  Atlas  P.  C.  Co.,  Ilasco,  Mo. 

27.  Atlas  P.  C.  Co.,  Ilasco,  Mo.     E.  Davidson,  analyst. 

28.  Catskill  P.  C.  Co.,  Smith's  Landing,  N.  Y. 

29-30.  Helderberg  P.  C.  Co.,  Howe's  Cave,  N.  Y.     Black,  analyst. 
31-33.  Cayuga  P.  C.  Co.,  Portland  Point,  N.  Y.     J.  H.  McGuire,  analyst. 

34.  Glens  Falls  P.  C.  Co.,  Glens  Falls,  N.  Y.     Mineral  Industry,  vol.  6,  p.  97. 

35.  Ironton  P.  C.  Co.,  Ironton,  Ohio.     C.  D.  Quick,  analyst. 

36.  Alma  P.  C.  Co.,  Wellston,  Ohio.     21st  Ann.  Rep,  U.  S.  Geol.  Survey,  pt.  6,  p.  402. 
37-39.  Diamond  P.  C.  Co.,  Middle  Branch,  Ohio.     E.  Davidson. 

40.  Wellston  P.  C.  Co.,  Wellston,  Ohio.     W.  S.  Trueblood,  analyst. 
41-44.  Crescent  P.  C.  Co.,  Wampum,  Pa.     Robertson  Bros.,  analysts.     Report  Q.  Q.,  Penna.  GeoL 

Surv.,  p.  107. 
45.  Virginia  P.  C.  Co.,  Craigsville,  Va.     Cement  Industry,  p.  235. 


G16  CEMENTS,  LIMES,  AND  PLASTERS. 

the  work  that  has  been  done  by  geologists  in  the  areas  under  consider- 
ation. Most  States  now  have  geological  surveys,  and  there  are  few 
important  limestone  deposits  that  have  not  been  located  and  examined 
by  these  organizations  or  by  the  Federal  survey.  Numerous  reports  * 
on  these  subjects  have  been  issued  by  State  or  Federal  Geological'  Sur- 
veys, and  these  reports  can  usually  be  obtained  free  or  at  a  merely 
nominal  price  on  application'  to  th^  proper  officials.  If  such  a 
report  can  be  obtained  covering  the  area  to  be  examined  it  will  da 
away  with  a  lot  of  preliminary  work  on  the  part  of  the  prospector  or 
engineer.  t. 

Preliminary  Examination. — In  commencing  work,  it  is  desirable 
to  prepare  a  rough  map  of  the  area.  For  this  purpose  high  accuracy 
is  not  required,  and  a  pocket  compass  or  Brunt  on  compass,  with  a  Locke 
level,  and  a  small  protractor  will  be  the  only  instruments  required. 
With  these  a  map  can  be  made  and  plotted  on  a  scale  of  50  or  100,  feet 
to  the  inch,  distances  being  measured  by  pacing.  The  location  of  any 
natural  outcrop,  pits,  wells,  road  or  railroad  cuts,  and  streams  should 
be  shown  on  the  map,  and  their  relative  elevations  ascertained  as  exactly 
as  possible.  When  the  rocks  are  lying  almost  horizontally,  the  loca- 
tions of  the  outcrops  are  of  far  less  importance  than  their  elevations. 

If  there  are  sufficient  good  exposures  of  the  rock,  in  either  natural 
or  artificial  cuts,  samples  should  be  collected  from  these  outcrops.  The 
weathered  part  of  the  rock  should  be  rejected,  care  being  taken  that 
the  samples  represent  the  fresh,  undecomposed  rock.  When  the  natural 
exposures  are  not  satisfactory,  it  will  be  necessary  to  secure  samples 
by  trenches,  pits,  or  boring. 

Most' of  the  limestones  with  which  the  cement  manufacturer  may 
have  to  deal  occur  in  beds  or  layers  which  are  practically  horizontal 
In  the  Appalachian  and  other  disturbed  districts,  however,  the  beds, 
may  be  tilted  to  a  considerable  angle  with  the  horizontal,  and  in  rare 
cases  they  may  even  be  almost  vertical.  Usually  samples  from  differ- 
ent parts  of  the  same  bed  (within  reasonable  distances  of  each  other) 
will  be  very  similar  in  composition;  but,  on  the  contrary,  two  adjoin- 
ing beds  may  differ  greatly  from  each  other. 

In  sampling,  therefore,  it  is  desirable  to  collect  at  least  one  speci- 
men from  each  bed  or  layer,  noting  the  thickness  and  position  of  the 
bed.  Even  thin  beds  should  not  be  neglected,  for  a  4-inch  layer  of 
highly  magnesian  rock  might  prove  a  serious  drawback  to  the  eco- 
nomical working  of  the  quarry  if  its  presence  were  unsuspected. 

*  See  reference  lists  on  pp.  92-94. 


LIMESTONES.  317 

When  the  beds  are  horizontal  or  nearly  so  a  stream  gorge  or  road 
cut  may  furnish  a  good  idea  of  the  character  of  the  different  beds.  In 
default  of  such  an  exposure,  it  will  be  necessary  to  sink  test  pits  to 
the  rock,  unless  it  is  exposed  conveniently  at  the  surface,  and  then 
secure  samples  from  various  depths  by  drilling.  Whenever  possible 
the  diamond-drill  is  the  most  satisfactory  exploring  device,  for  it  is 
practically  an  automatic  sampler. 

When  the  beds  are  steeply  inclined,  a  trench  cut  across  at  right 
angles  to  the  bedding  will  expose  a  series  of  beds  and  enable  each  to 
be  sampled. 

If  the  beds  are  horizontal  or  nearly  so,  and  the  various  samples 
show  little  difference  in  composition,  such  a  preliminary  examination 
as  is  described  above  may  be  all  that  is  required.  In  case  the  rock- 
beds  dip  at  high  angles,  or  if  folds  or  faults  are  suspected,  it  will  be 
safest  to  call  in  a  geologist  or  mining  engineer  as  associate.  If  the 
analyses  disagree  markedly,  it  will  be  advisable  to  undertake  a  more 
detailed  examination  of  the  area. 

Detailed  Mapping  and  Sampling. — A  much  more  detailed  examina- 
tion is  always  desirable  before  the  actual  erection  of  the  plant  is  com- 
menced. Such  an  examination  will  decide  the  best  possible  location 
for  the  quarry,  and  should  also  give  data  which  will  aid  in  keeping  a 
uniform  mix. 

For  these  purposes  a  contour  map,  with  1-,  5-,  or  10-foot  contours, 
according  to  the  slope,  on  a  scale  of  25  feet  to  the  inch,  should  be  care- 
fully prepared.  The  area  to  be  examined  should  be  laid  out  in  25-  or 
50-foot  squares  and  their  corners  marked  and  numbered  to  correspond 
to  their  locations  on  the  map.  At  least  three  good  points  should  be 
selected  as  permanent  bench-marks,  far  enough  away  from  the  pros- 
pective quarry-site  as  not  to  be  disturbed  by  excavation  or  blasting, 
and  the  locations  and  elevations  of  these  points  should  be  carefully 
determined  and  placed  on  the  map. 

Sampling  should  now  be  taken  up  carefully.  For  final  work  this 
can  be  done  satisfactorily  only  with  the  diamond  drill.  Drill-holes 
should  be  put  down  at  every  corner  of  the  50-foot  squares.  Each  5 
feet  of  the  core  should  be  sampled  and  analyzed  separately,  to  a  depth 
of  at  least  50  feet.  If  the  rock  dips  steeply,  or  if  for  any  other  reason 
a  deep,  narrow  quarry  seems  probable,  the  drilling  should  be  continued 
to  200  feet.  If  the  cores  from  adjacent  bore-holes  give  closely  similar 
analyses,  closer  drilling  is  not  necessary.  But  if  two  samples  taken 
at  the  same  depth  from  two  adjoining  holes  show  differences  of  more 
than  3  per  cent  in  their  lime  carbonate,  or  more  than  1J  per  cent  in 


.  -    . .    ..  v 


.... 


of  Ac 

tioD  ft  viB  be  safe  to 
stone  in  the  quarry,  and  to 

rulrur  ;>>*  of  limestone  per  year.    His  would  cnrnryoMJ  to  a 
of  about  4}  feet,  over  one  acre .  per  year  per  kim. 

Chalk  and  Other  Soft  Limestones. 

Cbafl^  propaly  speaking,  is  a  pore  carbonate  of  Erne  composed  of 
of  tfa*  flifilg  of  minute  organisms,  ****"**£  windi  those  of 

A  or^mmfr  if  ^pinE  JUP£  cspcojui^r  t^roffn  ^y  h^^t \ ,  j.  DC?  f'fi^rTsf^  mid.  90»i  .DDQGSWQMMQB  * 
discussed  in  this  chapter  agree  not  only  in  having  usually  originated 
in  this  wayy  but  also  in  being  rather  soft  and  therefore  readily  and 
cheaply  crushed  and  pulverized.  As  Portland-cement  materials  they 
are  therefore  almost  ideal.  One  defect,  however,  which  to  a  saaH 
extent  counterbalances  their  obvious  advantages  is  the  fact  that  most 
of  these  soft,  chalky  limestones  absorb  water  quite  readily.  A  chalky 
limestone  which  in  a  dry  season  will  not  earn*  over  2  per  cent  of  n 
lire  as  quarried  ma}'  in  consequence  of  prolonged  wet  weather  show  as 
high  as  15  or  20  per  cent  of  water.  This  difficulty  can  of  course  be 
avoided  if  care  be  taken  in  quarrying  to  avoid  unnecessary  exposure 
to  water  and,  if  necessary,  to  provide  facilities  for  storing  a  supply  of 
the  raw  materials  during  wet  seasons. 

Origin  of  chalk. — The  term  chalk  is  properly  applied  to  a  fine-grained 
and  usually  very  pure  limestone,  formed  largely  or  entirely  of  the  cal- 
cLrcous  shells  of  microscopic  organisms.  These  shells  are  chiefly  of 
the  minute  Foraminifera,  though  equally  small  and  smaller  calcareous 
particles  of  various  shapes  also  occur.  Calvin  describes  *  a  section  of 
chalk  from  Iowa  as  follows: 

*  Reports  Iowa  Geological  Survey,  vol.  3,  p.  224.     1  > 


LIMESTONES.  319 

"In  thin  sections  under  the  microscope  the  unbroken  shells  of  Foram- 
inifera  are  very  conspicuous.  They  lie  in  close  proximity  to  each 
other,  and  their  inflated  chambers,  filled  with  crystals  of  calcite,  some- 
times occupy  more  than  one  third  the  area  of  the  entire  field.  It  is 
certain  that  more  than  one  fourth,  and  in  some  instances  more  than 
one  third,  of  the  volume  of  the  chalk  is  composed  of  foraminiferal  shells 
still  practically  entire.  The  matrix  in  which  the  shells  are  embedded 
is  made  up  of  a  variety  of  objects,  the  most  numerous  and  the  most 
conspicuous  under  proper  amplification  being  the  circular  or  elliptical 
calcareous  discs  known  as  coccoliths.  The  small  rodlike  bodies  to 
which  the  name  rhabdoliths  has  been  applied  are  not  very  common, 
although  their  pressure  is  easily  detected  with  a  moderately  high-power 
objective.  Mingled  with  coccoliths  and  rhabdoliths  are  numerous 
fragments  that  are  evidently  the  debris  resulting  from  comminution  of 
foraminiferal  shells.  When  the  chalk  is  treated  with  acid  there  remains 
a  small  amount  of  insoluble  matter  consisting  of  clay,  fine  grains  of 
quartz  sand,  minute  pebbles  not  exceeding  5  millimeters  in  diameter, 
and  a  very  few  internal  casts  of  the  chambers  of  Foraminifera.  Nearly 
all  the  foraminiferal  shells  have  the  chambers  filled  with  calcite;  a  few 
have  these  cavities  still  empty;  but  in  a  small  number  of  cases  the 
chambers  were  filled  with  an  opaque,  insoluble  mineral,  probably  silica 
deeply  stained  with  iron  oxide,  that  remains  as  perfect  internal  casts 
after  the  shell  has  been  dissolved  in  acid.  The  amount  and  compo-' 
sition  of  the  residuum  varies  with-  the  purity  of  the  chalk.  In  some 
samples  it  scarcely  exceeds  1  per  cent,  hi  others  it  is  equal  to  10  per 
cent." 

Chalk  was  probably  deposited  in  deep,  quiet  water  little  affected 
by  debris  from  the  land.  At  present  material  of  exactly  similar  type 
is  being  formed  hi  the  deeper  portions  of  the  Xorth  Atlantic  and  other 
oceanic  basins. 

Distribution  of  chalk  and  soft  limestones. — Both  the  true  chalks 
and  the  other  soft  limestones  here  considered  are  of  comparatively  recent 
geologic  age,  occurring  only  in  Cretaceous  or  Tertiary  roc*ks.  There 
is  also  a  certain  geographic  unity  apparent,  for  both  types  occur  only 
along  the  Atlantic  and  Gulf  coasts  and  in  the  Western  States.  For 
detailed  information  regarding  the  distribution  of  these  rocks  reference 
should  be  made  to  the  papers  and  reports  listed  on  page  322.  In  the 
present  place  only  a  summary  can  be  given  covering  the  more  impor- 
tant features  of  the  subject. 

The  true  chalks  occur  only  in  formations  of  Cretaceous  age  in  certain 
Southern  and  Western  States.  The  principal  chalk  deposits  available 


320  CEMENTS,  LIMES,  AND   PLASTERS. 

for  use  in  Portland-cement  manufacture  occur  in  three  widely  separated 
areas  occupying  respectively  (a)  parts  of  central  Alabama  and  north- 
eastern Mississippi,  (b)  southwestern  Arkansas  and  central  Texas,  and 
(c)  parts  of  Iowa,  Nebraska,  North  and  South  Dakota,  Colorado,  and 
other  States  of  the  Great  Plains  region.  Though  the  chalk  is  in  all  these 
areas  of  approximately  the. same  age  and  character,  the  formations 
containing  it  have  been  given  different  names — i.e.,  the  Selma  chalk, 
in  Alabama  and  Mississippi;  the  Whitecliffs  chalk,  in  Arkansas;  the 
Austin  chalk,  in  Texas;  and  the  Niobrara  chalk,  in  the  Great  Plains 
region. 

In  addition  to  the  true  chalks,  soft  limestones  of  Tertiary  age  occur 
in  all  the  Atlantic  and  Gulf  coast  States  from  Virginia  to  Mississippi 
inclusive,  as  well  as  in  California.  These  are  the  materials  commonly 
described  as  "marls"  in  the  older  geological  reports,  though  they  are 
in  no  way  related  to  the  fresh-water  marls  now  so  largely  used  in  Port- 
land-cement manufacture,  discussed  in  Chapter  XXV. 

Physical  Properties.  —  When  dry,  the  chalks  and  soft  limestones, 
are  commonly  considerably  lighter  than  the  hard  limestones.  As 
noted  on  a  previous  page,  the  chalky  limestones  may  run  as  low  in 
specific  gravity  as  1.85,  corresponding  to  a  weight  of  about  110  Ibs.  per 
cubic  foot,  while  the  hard,  compact  limestones  in  common  use  range  in 
specific  gravity  from  2.3  to  2.9,  corresponding  approximately  to  a  range 
in  weight  of  from  140  to  185  Ibs.  per  cubic  foot. 

The  low  weight  above  quoted  is,- however,  exceptional,  and  the  soft 
limestones  may  be  expected  to  range  between  125  and  150  Ibs.  per  cubic 
foot  when  dry.  They  are  usually  very  porous,  however,  and  but  brief 
exposure  to  water  will  increase  their  weight  and  moisture  content  re- 
markably. This,  indeed,  is  their  single  defect  from  the  point  of  view 
of  the  cement  manufacturer,  for  during  a  rainy  season  or  with  a  badly 
drained  quarry  he  may  have  to  handle  a  material  carrying  15  or  20  per 
cent  of  moisture. 

Otherwise  they  are  admirable  cement  materials,  being  soft  and 
easily  quafried  and  ground. 

Composition  of  chalks  and  soft  limestones  used  in  cement-plants. 
— In  composition  the  chalks  and  other  soft  limestones  vary  from  a  rather 
pure  lime  carbonate  low  in  both  magnesia  and  clayey  matter  to  an 
impure  clayey  limestone  of  about  the  composition  of  the  Lehigh  district 
cement  rock.  Magnesium  carbonate  is  rarely  present  in  quantities  of 
over  2  or  3  per  cent,  but  alkalies,  sulphur,  and  phosphoric  acid  may 
occur  in  sufficient  percentages  to  require  careful  considerations. 


LIMESTONES. 


321 


TABLE  147. 
ANALYSES  OF  PURE  CHALKS  USED  IN  AMERICAN  CEMENT-PLANTS. 


1. 

2, 

3. 

4. 

5. 

6. 

7 

8. 

Silica  (SiO2)  

5.33 

4.42 

6.09 

3.83 

4.14 

2.15 

5.77 

2.22 

Alumina  (A12O3) 

\3.03 

f  2.21 

ir.oa 

3.52 
1.20 

1    2.31 

ri.si 

12.72 

}2.72 

2.14 

JO.  92 
\0.18 

Iron  oxide  (Fe2O3)  .  .  . 

Lime  (CaO)  

50.53 

53.36 

49.24 

52.16 

51.00 

52.48 

50.45 

54.08 

Magnesia  (MgO)  

0.55 

n.  d. 

n.  d. 

0.14 

tr. 

n.  d. 

0.28 

0.10 

Alkalies  (K2O,Na2O). 

n.  d. 

n.  d. 

n.  d. 

tr. 

n.  d. 

n.  d. 

n.  d. 

Sulphur  trioxide  (SO3) 

n.  d. 

n.  d. 

n.  d. 

0.20 

0.50 

n.  d. 

n.  d. 

Carbon  dioxide  (CO2) 
Water    

50.30 
n.<*. 

n.  d. 
n.  d. 

n.  d. 
n.  d. 

1.41,64 

J39.99 
[n.  d. 

n.d. 
n.  d. 

40.00 
n.  d. 

}42.50 

1.  Whitecliffs  P.  C.  Co.,  Whitecliffs,  Ark.       18th  Ann.  Rep.,  U.  S.  Geol.  Survey,  pt.  5,  p.  1174. 
2-3.  Trans.  Amer.  Institute  Mining  Engrs.,  vol.  21,  p. 

4.  Western  P.  C.  Co.,  Yankton,  S.  D.     C.  B.  McVay,  analyst. 

5.  "         Mineral  Industry,  vol.  1,  p.  52. 

6.  "  "  "  "  "          vol.  6,  p.  97. 

7.  Alamo  Cement  Works,  San  Antonio,  Texas.     22d  Ann.  Rep.  U.  S.  Geol.  Survey,  pt.  3,  p.  737. 

8.  Almendares,  P.  C.  Co.,  Marinao,  Cuba.     Engineering  Record,  vol.  49,  p.  36. 

TABLE  148. 
ANALYSES  OF  CLAYEY  CHALKS  USED  IN  AMERICAN  CEMENT-PLANTS. 


Silica  (SiO2)  

9.88 

7.64 

12.13 

13  32 

Alumina  (A12O3)  

/4.171 

Iron  oxide  (Fe2O3)  

i      6.20 

7.62 

1  3.28J 

8.74 

Lime  (CaO) 

43  19 

45  20 

42  04 

41  41 

Magnesia  (MgO) 

0  52 

0  59 

0  44 

0  67 

Sulphur  trioxide  (SO3) 

n  d 

1  62 

n  d 

0  27 

Carbon  dioxide  (CO2) 

34  49 

36  06 

33  51 

33  26 

Water 

5  72 

1  36 

n  d 

n  d 

Examining  chalk  deposits.* — The  chalk  deposits  of  most  of  the 
States  have  been  carefully  mapped  by  geological  surveys,  and  much 
time  will  be  saved  by  procuring  and  studying  the  proper  reports.  These 
will  give  general  data  on  the  distribution  and  character  of  the  chalk 
formations. 

In  examining  chalk  deposits  it  is  well  to  recollect  that  they  are  always 
found  hi  thick  and  almost  horizontal  beds.  Stream  ravines  usually 
give  good  natural  sections,  which  will  serve  to  give  a  preliminary  idea 
of  the  character  of  the  rock.  In  securing  samples,  the  earth-auger 
gives  satisfactory  results  in  most  chalk  deposits,  because  the  material 
is  usually  soft  enough  to  be  penetrated  readily  by  this  tool. 

The  principal  impurities  to  be  guarded  against  are  nodules  of  pyrite 
and  grains  of  sand,  both  of  which  are  very  common  in  many  American 
chalk  deposits. 


*  See  pages  315-318  for  further  notes  on  this  subject. 


322  CEMENTS,  LIMES,  AND  PLASTERS. 

List  of  references  on  chalks  and  soft  limestones. — The  following 
papers  deal  largely  with  the  chalky  limestones  of  the  United  States. 
For  convenience  of  reference  those  which  consider  chiefly  the  origin  and 
structure  of  chalk  are  marked  A ;  those  which  describe  its  distribution  in 
certain  States  or  areas  are  marked  B. 

B.  Branner,  J.  C.  The  cement  materials  of  southwest  Arkansas.  Trans. 
Am.  Inst.  Min.  Engrs.,  vol.  27,  p£.  42-63.  1898. 

A.  Calvin,  S.  The  Niobrara  chalk.  Proc.  Amer.  Assoc.  Adv.  Sci.,  vol.  43, 
pp.  197-217.  1895. 

A.  Calvin,  S.  Composition  and  origin  of  Iowa  chalk.-  Reports  Iowa  Geolog- 
ical Survey,  vol.  3,  pp.  211-236.  1895. 

A.  Dawson,  G.  M      Note  on  the  occurrence  of  Foraminifera,  etc.,  in  the  Creta- 

ceous rocks  of  Manitoba.     Canadian  Naturalist,  vol.  7,  no.  5.     1874. 

B.  Eckel,  E.  C.     Cement  materials  and  cement  industries  of  the  United  States. 

Bulletin  243,  U.  S.  Geological  Survey.     1905. 
B.  Hill,  R.  T.     A  brief  description  of  the  Cretaceous  rocks  of  Texas  and  their 

economic  value.     1st  Ann.  Report  Texas  Geological  Survey,  pp.  103- 

144.     1890. 
A.  B.  Hill,  R.  T.     Neozoic  geology  of  southwestern  Arkansas.     Ann.  Rep. 

Arkansas  Gecl.  Survey  for  1888,  vol.  2. 

A.  Hill,   R.   T.     The  foraminiferal  origin  of   certain  Cretaceous   limestones. 

American  Geologist,  Sept.,  1889. 

B.  Smith,  E.  A      Report  on  the  geology  of  the  Coastal  Plain  of  Alabama. 

Report  Alabama  Geological  Survey,  759  pp.     1894. 
B.  Smith,  E.  A.     Alabama 's  resources  for  the  manufacture  of  Portland  cement. 

Proc.  Ala.  Industrial  and  Scientific  Society,  vol.  5,  pp.  44-51.     1895. 
B.  Smith,  E.  A.     The  cement  resources  of  central  and  southern  Alabama. 

Senate  Document  No.  19,  58th  Congress,  1st  session.     1903. 
B.  Smith,  E.  A.     Cement  resources  of  Alabama.     Bulletin  225,  U.  S.  Geological 

Survey,  pp.  424-447.     1904. 
B.  Smith,   E.   A.     Cement   resources    of    Alabama.      Bulletin    8,    Alabama 

Geological  Survey.     12mo,  93  pp.     1904. 
B.  Taff,  J.  A.     Chalk  of  southwestern  Arkansas,  with  notes  on  its  adaptability 

to  the  manufacture  of  hydraulic  cement.     22d  Ann.  Rep.  U.  S.  Geol. 

Survey,  pt.  3,  pp.  687-742.     1902. 
A.  Williston,  S.  W.     Chalk  from  the  Niobrara  Cretaceous  of  Kansas.     Science, 

vol.  16,  p.  294.     1890. 
A.  Williston,  S.  W.     On  the  structure  of  the  Kansas  chalk.     Trans.  Kansas 

Acad.  Sci.,  vol.  12,  p.  100.     1890. 


CHAPTER  XXIV. 
ARGILLACEOUS  LIMESTONE:    CEMENT  ROCK. 

THE  term  "cement  rock"  is  here  used  to  include  all  the  very  clayey 
limestones  carrying  from  50  to  80  per  cent  of  lime  carbonate,  with 
correspondingly  high  percentages  of  argillaceous  matter,  and  less  than 
8  per  cent  of  magnesium  carbonate.  It  is  evident  that  an  argillaceous 
limestone  low  in  magnesia,  and  containing  approximately  75  to  77  per 
cent  of  lime  carbonate  and  20  per  cent  or  so  of  clayey  materials  (silica, 
alumina,  and  iron  oxide)  would  be  the  ideal  material  for  use  in  the 
manufacture  of  Portland  cement;  for  a  rock  of  this  composition  would 
contain  within  itself,  mixed  in  the  proper  proportions,  all  the  ingre- 
dients necessary  for  the  manufacture  of  a  good  Portland.  Such  an 
ideal  rock  would  require  the  addition  of  no  other  raw  material,  but  when 
burnt  alone  would  give  a  good  cement. 

This  ideal  cement  material  is,  of  course,  never  realized  in  practice, 
but  certain  deposits  of  clayey  limestone  approach  it  very  closely  in 
composition.  A  limestone  carrying  70  or  80  per  cent  of  lime  car- 
bonate and  20  to  30  per  cent  clayey  matter  will  require  the  addition 
either  of  pure  limestone  or  of  clay  in  order  to  bring  it  to  the  desired 
composition  for  a  Portland-cement  mixture.  But  it  will  be,  of  itself, 
so  near  to  the  correct  composition  that  it  will  need  but  little  of  the  extra 
raw  material  to  make  it  absolutely  perfect.  Deposits  of  such  "cement 
rocks"  possess  important  technologic  advantages,  and  have  been  sought 
for  with  great  industry.  Many  such  deposits  of  clayey  limestones,  low 
in  magnesia,  occur  in  various  parts  of  the  United  States,  but  few  of  them 
are  well  located  with  regard  to  transportation  routes*  fuel  supplies,  and 
markets. 

The  most  important  of  these  argillaceous  limestone,  or  "  cement-rock  ", 
deposits  is  at  present  that  which  is  so  extensively  utilized  in  Portland- 
cement  manufacture  in  the  "Lehigh  district"  of  Pennsylvania  and 
New  Jersey,  though  similar  "cement  rocks "  occur  in  many  other  States. 
As  the  Lehigh  district  still  produces  over  half  of  all  the  Portland  cement 
manufactured  in  the  United  States,  its  raw  materials  will  be  described 
below  in  some  detail,  after  which  other  areas  of  "cement  rock"  will 
be  briefly  noted. 

323 


324  CEMENTS,  LIMES,  AND  PLASTERS. 

Cement  Rock  of  the  Lehigh  District,  Pennsyivania-New  Jersey. 

The  "Lehigh  district"  of  the  cement  manufacturer  has  been  so 
greatly  extended  in  recent  years  that  the  name  is  now  hardly  appli- 
cable. Originally  it  included  merely  an  area  about  4  miles  square, 
located  along  the  Lehigh  River  partly  in  Lehigh  County  and  partly  in 
Northampton  County,  and.  containing  the  villages  of  Egypt,  Coplay, 
Northampton,  Whitehall,  and  Siegfried.  The  cement-plants  which  were 
early  located  here  secured  control  of  most  of  the  cement-rock  deposits  in 
the  vicinity,  and  plants  of  later  establishment  have  therefore  been  forced 
to  locate  farther  away  from  the  original  center  of  the  district.  At 
present  the  district  includes  parts  of  Berks,  Lehigh,  and  Northampton 
Counties,  Pa.,  and  Warren  County,  N.  J.,  reaching  from  near  Reading, 
Pa.,  at  the  southwest,  to  a  few  miles  north  of  Stewartsville,  N.  J.,  at  the 
northeast.  It  forms  an  oblong  area  about  25  miles  in  length  from 
southwest  to  northeast  and  about  4  miles  in  width.  Within  this  area 
about  twenty  Portland-cement  plants  are  now  in  operation,  and  the 
Portland  cement  produced  in  this  relatively  small  district  amounts  to 
over  half  of  the  entire  United  States  output. 

Geology  of  the  district. — Within  the  "  Lehigh  district "  three  geo- 
logic formations  occur,  all  of  which  must  be  considered  in  attempting  to 
account  for  the  distribution  of  the  cement  materials  used  here.  These 
three  formations  are,  in  descending  order,  the  (1)  Hudson  shales,  slates, 
and  sandstones;  (2)  Trenton  limestone  (Lehigh  cement  rock);  (3)  Kitta- 
tinny  limestone  (magnesian).  As  all  these  rocks  dip,  in  general,  north- 
westward, the  Hudson  rocks  occupy  the  northwestern  portion  of  the 
district,  while  the  cement  rock  and  magnesian  limestone  outcrop  in 
succession  farther  southeast. 

Hudson  shale. — This  series  includes  very  thick  beds  of  dark-gray 
to  black  shales,  with  occasional  thin  beds  of  sandstone.  In  certain 
localities,  as  near  Slatington  and  Bangor,  Pa.,  and  Newton,  N.  J.,  these 
shales  have  been  so  altered  by  pressure  as  to  become  slates,  the  quarry- 
ing of  which  now  supports  a  large  roofing-slate  industry. 

The  composition  of  the  typical  shales  and  slates  of  the  Hudson  for- 
mation is  well  shown  by  the  following  analyses  (Table  149). 

The  geographic  distribution  of  the  Hudson  shales  and  slates  in  the 
Lehigh  district  can  be  indicated  only  approximately  without  the  pres- 
entation of  a  geologic  map  of  the  area.  They  cover  practically  all  of 
Northampton,  Lehigh,  and  Berks  counties  north  of  a  line  passing 
through  Martins  Creek,  Nazareth,  Bath,  Whitehall,  Ironton,  Guthsville, 
Monterey,  Kutztown,  Molltown,  and  Leesport. 

The  rocks  of  the  Lehigh  district  have  a  general  dip  to  the  northwest, 


ARGILLACEOUS  LIMESTONE:  CEMENT  ROCK. 


325 


TABLE  149. 
ANALYSES  OF  HUDSON  SHALE  AND  SLATE  IN  PENNSYLVANIA  AND  NEW  JERSEY. 


1. 

2. 

3. 

4. 

Silica  (SiO  ) 

Per  Cent. 
68   62 

Per  Cent. 
68  00 

Per  Cent. 
56   60 

Per  Cent. 
*  76  22 

Alumina  (Al  Oo) 

12  68 

14   40 

21  00 

Iron  oxide  (Fe2O3)      

4  20 

5  40 

5  65 

|    13.05 

Lime  (CaO)             

1  31 

2  68 

3  42 

2  67 

Magnesia  (MgO)     

1  80 

1  51 

2  30 

0  93 

Alkalies        

3  73 

0  11 

0  50 

n.  d. 

Carbon  dioxide  (CO,).  
Water  (H2O) 

2.99 
4  47 

2.30 
2  70 

2.20 
3  00 

n.d. 
n  d 

*  Insoluble. 

1.  East  Bangor,  Pa.     20th  Ann.  Rep.  U.  S.  Geol.  Survey,  pt.  6,  p.  436. 

2.  1  mile  northwest  of  Colemanville,  N.  J.     Geology  New  Jersey,  1868,  p.  136. 

3.  Delaware  Water  Gap,  N.  J.     Geology  New  Jersey,  1868,  p.  136. 

4.  Lafayette,  N.  J.     Kept.  New  Jersey  State  Geol.  for  1900,  p.  74. 

though  there  are  numerous  local  exceptions  to  this  rule.  The  lowest 
beds  of  the  Hudson  series,  therefore,  are  those  which  outcrop  along  the 
southern  boundary  of  the  formation,  as  above  outlined.  These  lowest 
beds  carry  much  more  lime  and  less  silica,  alumina,  and  iron  than  the 
higher  beds  whose  analyses  are  given  in  table  149..  The  lowest  beds 
form  a  natural  transition  into  the  underlying  cement  rock. 

Trenton  limestone. — The  Lehigh  cement  rocks,  which  are  equivalent 
in  age  to  the  Trenton  limestone  beds  of  New  York,  are  made  up  of  a 
series  of  argillaceous  limestones.  The  formation  appears  to  vary  in 
thickness  from  150  feet  in  New  Jersey  to  250  feet  or  even  more  at  Naz- 
areth and  on  the  Lehigh  River.  Its  upper  beds  near  the  contact  with 
the  overlying  Hudson  shales  are  very  shaly  or  slaty  black  limestones 
carrying  approximately  50  to  60  per  cent  of  lime  carbonate  and  40  to  50 
per  cent  of  silica,  alumina,  iron,  etc.  Lower  in  the  formation  the  per- 
centage of  lime  steadily  increases,  while  that  of  clayey  material  decreases 
correspondingly,  until  near  the  base  of  the  formation  the  rock  may  carry 
from  85  to  95  per  cent  of  lime  carbonate  with  only  5  to  15  per  cent  of 
impurities.  This  change  in  chemical  composition  is  accompanied  by  a 
change  in  the  appearance  and  physical  character  of  the  rock,  which  grad- 
ually loses  its  slaty  fracture  and  blackish  color  as  the  percentage  of  lime 
increases,  until  near  the  base  of  the  formation  it  is  often  a  fairly  mas- 
sively bedded  dark-gray  limestone.  Even  so,  it  can  usually  be  readily  dis- 
tinguished from  the  magnesian  Kittatinny  limestone,  described  below,  for 
the  cement  rock  is  always  darker  than  the  magnesian  limestone  and  con- 
tains none  of  the  chert  beds  which  are  so  common  in  the  magnesian  rock. 

The  Lehigh  cement  rock  is  never  nearly  so  high  in  magnesia  as  is 
the  underlying  Kittatinny  limestone.  It  does,  however,  carry  con- 


326 


CEMENTS,  LIMES,  AND   PLASTERS. 


siderable  magnesia  (as  compared  with  other  Portland-cement  materials) 
throughout  its  entire  thickness,  and  few  analyses  will  show  less  than 
4  to  6  per  cent  of  magnesium  carbonate.  The  following  series  of 
analyses  is  fairly  representative  of  the  lower,  middle,  and  upper  beds 
of  the  formation.  The  specimens  from  the  upper  beds,  near  the  Hud- 
son shales,  show  considerably  less  lime  and  more  clayey  matter  than 
those  from  the  lower  parts -of  the  formation. 

TABLE  150. 
ANALYSES  OF  TRENTON  LIMESTONE  (LEHIGH  CEMENT  ROCK). 


l. 

2. 

3. 

4. 

5. 

Silica  (SiO  ) 

Per  Cent. 
1  83 

Per  Cent. 
5  03 

Per  Cent. 

8  33 

Per  Cent. 
11    90 

Per  Cent 
11    71 

Alumina  (A12O3)  
Iron  oxide  (1  e2O3)    

.CO 
51 

2.0G 
1  23 

4.C3 
1  32 

4.42 

1.70 

4.36 
1  62 

Lime  (CaO)           

53  64 

49  73 

45  45 

44  18 

43  47 

Magnesia  (MgO)         

.81 

1  02 

1  34 

1   18 

1  82 

Carbon  dioxide  (CO2)  

43.03 

40.19 

37.18 

3G.01 

33  15 

6. 

7. 

8. 

9. 

10. 

Silica  (SiO2)              

Per  Cent. 
11    11 

Per  Cent. 
17   04 

Per  Cent. 
22   71 

Per  Cent. 
19  53 

Per  Cent. 
24  45 

Alumina  (A12O3)     

4  40 

6  90 

5  84 

6  03 

5  68 

Iron  oxide  (Fe2O3)  

1  91 

2   13 

2  13 

1  70 

1  57 

Lime  (CaO)     

42  51 

37  53 

36.50 

35  71 

35  00 

Magnesia  (MgO)  

2.89 

2.17 

1.69 

3.33 

2  21 

Carbon  dioxide  (CO2)  

36.57 

32.88 

30.52 

32.73 

29.89 

Ann.  Kept.  New  Jersey  State  Geologist  for  1COO,  p.  95. 

The  specimens  whose  analyses  are  given  above  were  mostly  from 
the  vicinity  of  Belvidere,  N.  J.,  and,  though  representative  in  other 
respects,  seem  to  have  been  rather  lower  in  magnesia  than  the  usual 
run  of  the  Trenton  limestone  in  the  Lehigh  district. 

Kittatinny  magnesian  limestone. — Underlying  the  cement-rock  series 
is  a  very  thick  formation  consisting  of  light-gray  to  light-blue  massive- 
bedded  limestone,  with  frequent  beds  of  chert.  These  limestones  are 
predominantly  highly  magnesian,  though  occasionally  beds  of  pure 
non-magnesian  limestone  will  be  found  in  the  series.  The  magnesian 
beds  are,  of  course,  valueless  for  Portland-cement  manufacture,  but 
the  pure  limestone-beds  furnish  part  of  the  limestone  used  in  the  Lehigh 
district  for  addition  to  the  cement  rock.  An  excellent  example  of  this 
is  furnished  by  the  quarry  near  the  east  bank  of  Lehigh  River,  just 
above  Catasauqua.  In  this  quarry  most  of  the  beds  are  highly  mag- 
nesian, and  are  therefore  useful  only  for  road  metal  and  flux;  but  a 


ARGILLACEOUS   LIMESTONE:  CEMENT  ROCK. 


327 


few  pure  limestone  beds  occur,  and  the  material  from  these  low-magnesia 
beds  is  shipped  to  a  neighboring  cement-mill. 

Numerous  analyses  of  the  highly  magnesian  limestones  are  available, 
from  which  a  few  typical  results  have  been  selected  for  insertion  here. 
Analyses  of  the  purer  limestone,  used  to  add  to  the  cement  rock,  will 
be  found  in  the  table  on  page  329. 

TABLE  151. 
ANALYSES  OF  KITTATINNY  MAGNESIAN  LIMESTONE.* 


1. 

2. 

3. 

4. 

5. 

Silica  (SiO2)     

Per  Cent. 
9.9 

Per  Cent. 
9   9 

Per  Cent. 

8  8 

Per  Cent. 
5.5 

Per  Cent. 
9.8 

Alumina  (A12O3)  

I         1      -7 

Iron  oxiclc  (I(1e2Oo) 

I              ^ 

1.7 

0.8 

1.3 

3.7 

Lime  (CaO) 

27  6 

28  5 

29  4 

28  2 

26  4 

Magnesia  (MgO) 

17  9 

17  3 

17  8 

20  2 

15.1 

Carbon  dioxide  (CO2) 

41  9 

41  5 

42  8 

44.3 

45.0 

6. 

7. 

8. 

9. 

10. 

Silica  (SiO2)     

^»er  Cent. 
4.9 

Per  Cent. 
2  0 

Per  Cent. 
8.0 

Per  Cent. 
4.1 

Per  Cent. 
16.9 

Alumina  (Al  Oo) 

\     a   _ 

Iron  oxide  (Fe2Oo) 

|     6.5 

8.4 

5.3 

1.6 

1.0 

Lime  (CaO) 

27  3 

32  4 

26  3 

30  3 

28  3 

Magnesia  (MgO) 

14  6 

15  5 

17  4 

18  3 

15  3 

Carbon  dioxide  (CO2) 

44  8 

42  5 

41  1 

44  1 

38  9 

From  various  reports  of  the  New  Jersey  Geological  Survey. 


1.  Chandlers  Island,  Sussex  County,  N.  J. 

2.  Sparta,  Sussex  County,  N.  J. 

3.  Asbury,  Warren  County,  N.  J. 

4.  Oxford  Furnace,  Sussex  County,  N.  J. 


5,  6.  Clinton,  Hunterdon  County,  N.  J. 

7.  Pottersville,  Somerset  County,  N.  J. 

8,  9.  Peapack,  N.  J. 
10.  Annandale,  N.  J. 


While  all  of  the  above  analyses  are  from  New  Jersey  localities,  the 
magnesian  limestone  of  the  rest  of  the  Lehigh  district  would  give  closely 
similar  results. 

Throughout  most  of  the  Lehigh  district  the  practice  is  to  mix  a 
small  amount  of  pure  limestone  with  a  relatively  large  amount  of  the 
"cement  rock"  or  argillaceous  limestone,  in  order  to  bring  the  lime 
carbonate  content  up  to  the  percentage  proper  for  a  Portland-cement 
mixture.  As  above  noted,  all  of  the  "cement  rock"  is  derived  from  the 
middle  part  of  the  Trenton  formation,  where  the  beds  will  run  from 
60  to  70  per  cent  of  lime  carbonate.  The  pure  limestone  which  is  re- 
quired to  bring  this  material  up  to  the  necessary  percentage  of  lime 
carbonate  (75  per  cent  or  so)  is  obtained  either  from  the  lower  portion 
of  the  Trenton  itself  or  from  certain  low-magnesia  beds  occurring 
in  the  Kittatinny  formation. 


328  CEMENTS,  LIMES,  AND  PLASTERS. 

In  the  plants  located  near  Bath  and  Nazareth,  however,  the  practice 
has  been  slightly  different.  In  this  particular  area  the  cement-rock 
quarries  usually  show  rock  carrying  from  75  to  80  per  cent  of  lime  car- 
bonate. The  mills  in  this  vicinity,  therefore,  require  practically  no 
pure  limestone,  as  the  quarry  rock  itself  is  sufficiently  high  in  lime 
carbonate  for  the  purpose.  Indeed,  it  is  at  times  necessary  for  these 
plants  to  add  clay  or  slate,  instead  of  limestone,  to  their  cement  rock, 
in  order  to  reduce  its  content  of  lime  carbonate  to  the  required  figure. 
In  general,  however,  it  may  be  said  that  Lehigh  practice  is  to  mix  a 
low-carbonate  cement  rock  with  a  relatively  small  amount  of  pure  lime- 
stone, and  analyses  of  both  these  materials,  as  used  at  various  plants 
in  the  district,  are  given  below  in  Tables  152  and  153. 

Character  and  composition  of  the  cement  rock. — The  cement  rock  is  a 
dark-gray  to  black,  slaty  limestone,  breaking  with  an  even  fracture 
into  flat  pieces,  which  usually  have  smooth,  glistening  surfaces.  As 
the  percentage  of  lime  carbonate  in  the  rock  increases — i.e.,  as  the 
lower  beds  of  the  formation  are  reached — the  color  becomes  a  some- 
what lighter  gray  and  the  surfaces  of  the  fragments  lose  their  slaty 
appearance. 

The  range  in  composition  of  the  cement  rock  as  used  at  various 
plants  is  well  shown  in  the  first  eight  columns  of  the  above  table.  The 
nearer  the  material  from  any  given  quarry  or  part  of  a  quarry  approaches 
the  proper  Portland-cement  composition  (say  75  to  77  per  cent  lime 
carbonate)  the  less  addition  of  pure  limestone  will  be  necessary.  In 
by  far  the  greater  part  of  the  district,  as  above  noted,  the  cement  rock 
is  apt  to  run  about  65  to  70  per  cent  of  lime  carbonate,  therefore  re- 
quiring the  addition  of  a  proportionate  amount  of  limestone.  Most 
of  the  quarries  near  Bath  and  Nazareth,  however,  have  been  opened 
on  beds  of  cement  rock  running  considerably  higher  in  lime  carbonate 
and  occasionally  running  so  high  (80  per  cent,  etc.)  as  to  require  the 
addition  of  shale  or  clay  rather  than  of  pure  limestone. 

Character  and  composition  of  the  pure  limestones. — The  pure  lime- 
stones added  to  the  cement  rock  are  commonly  gray  and  break  into 
rather  cubical  fragments.  The  fracture  surfaces  show  a  finely  granu- 
lar structure  quite  distinct  in  appearance  from  the  slaty  cement  rock. 

In  composition  the  limestones  commonly  used  will  carry  from  90  to 
96  per  cent  of  lime  carbonate,  with  rather  less  magnesium  carbonate 
than  is  found  in  the  cement  rock.  All  of  the  cement-plants  own  and 
operate  their  own  cement-rock  quarries,  but  most  of  them  are  com- 
pelled to  buy  the  pure  limestone.  When  this  is  the  case  only  very 
pure  grades  of  limestone  are  purchased,  but  when  a  cement-plant  owns 


ARGILLACEOUS  LIMESTONE:  CEMENT  ROCK. 


329 


TABLE  152. 
ANALYSES  OF  HIGHLY  CLAYEY  LIMESTONES: 


'CEMENT  ROCK". 


! 

. 

3 

I? 

|g 

1 

1| 

g% 

g 

+ 

3'* 
«  .8 

J 

13 

fl£ 

I 

-§SB 

cc 

q 

33 

1 

3 

& 

3 

S~ 

o 

3 

d 

1 

18.30 

6.11 

1.85 

36.38 

2.13 

28.96 

2. 

29 

1.51 

2 

15.97 

7.53 

2.24 

34.34 

3.93 

32.80 

3 

17.32 

9.11 

38.59 

2.05 

32.55 

4 

19.62 

5.68 

39.08 

2.35 

33.25 

5 

16.77 

6.50 

41.37 

n.  d. 

n.  d. 

6 

15.73 

7.92 

39.62 

1.81 

33.08 

1.23 

7 

19.06 

4.44 

1.14 

38.77 

2.02 

32.66 

8 

22.22 

7.24 

0.92 

35.53 

2.19 

30.29 

2. 

72 

9 

19.08 

7.92 

37.56 

1.95 

31.62 

10 

14.20 

6.14 

41.51 

1.56 

34.47 

11 

14.52 

6.52 

41.17 

2.25 

34.79 

12 

15.05 

9.02 

1.27 

39.26 

1.90 

32.90 

1. 

46 

13 

15.20 

8. 

80 

38.70 

1.  47 

31.99 

TABLE  153. 
ANALYSES  OF  PURE  LIMESTONES  USED  FOR  MIXING  WITH  CEMENT  ROCK. 


Silica 
(Si02). 

Alumina 

(A1203). 

Iron 
Oxide 
(Fe203). 

Lime 
(CaO). 

Magnesia 

(MgO). 

Carbon 
Dioxide 
(C02). 

3.64 

52.93 

n.  d. 

n.  d. 

0. 

61 

5.56 

2 

40 

50.47 

1.00 

40.73 

3.02 

1. 

90 

51.55 

1.46 

42.08 

1.98 

0. 

70 

53.31 

0.97 

42.94 

2.14 

1. 

46 

52.84 

1.05 

42.64 

4.50 

0. 

82 

51.50 

0.66 

41.19 

3.40 

0. 

70 

52.53 

0.61 

41.94 

1.02 

0. 

48 

54.60 

0.53 

43.47 

0.08 

0. 

40 

54.90 

0.61 

43.80 

6.1 

3. 

5 

47.21 

2.35 

39.64 

its  limestone  quarry  material  running  as  low  as  85  per  cent  of  lime 
carbonate  is  often  used. 

Quarry  practice. — In  most  of  the  cement-rock  quarries  of  the 
Lehigh  district  the  rock  dips  from  15°  to  25°,  usually  to  the  northwest. 
At  a  few  quarries,  particularly  in  New  Jersey,  the  dip  is  much  steeper. 
The  quarries  are  opened  preferably  on  a  side-hill,  and  the  overlying 
stripping,  which  consists  of  soil  and  weathered  rock,  is  removed  by 
scrapers  or  shoveling.  The  quarry  of  the  Lawrence  Cement  Company 
has  been  extended  in  its  lower  levels  so  as  to  give  a  tunnel  through 
which  the  material  is  hoisted  to  the  mill.  Several  other  quarries  have 


330  CEMENTS,  LIMES,  AND  PLASTERS. 

been  carried  straight  down,  until  now  they  are  narrow  and  deep  pits, 
from  which  the  material 'is  hoisted  vertically.  The  Bonneville  Port- 
land Cement  Company's  quarry  is  an  extreme  example  of  this  type. 


FIG.  67. — Tunnel,  Lawrence  Cement  Co.,  Siegfried,  Pa. 

In  quarries  opened  on  a  side-hill,  so  as  to  have  a  long  and  rather 
low  working-face  and  a  floor  at  the  natural  ground  level,  the  rock  is 
commonly  blasted  down  in  benches,  sledged  to  convenient  size  for 
handling  and  crushing,  and  carried  by  horse  carts  to  a  point  in  the 
quarry  some  distance  from  the  face  where  the  material  can  be  dumped 
into  cars,  which  are  hauled  by  cable  to  the  mill.  Occasionally  the 
material  is  loaded  at  the  face  into  small  cars  running  on  temporary 
tracks.  The  loaded  cars  are  then  drawn  by  horses  or  pushed  by  men 
to  a  turntable,  where  they  are  connected  to  the  cable  and  hauled  to  the 
mill.  While  these  methods  seem  clumsy  at  first  sight,  they  are  capable 
of  little  improvement.  The  amount  of  rock  used  every  day  in  a  large 


ARGILLACEOUS  LIMESTONE:  CEMENT  ROCK  331 

mill   necessitates  very  heavy  blasting,   and   this   prevents   permanent 
tracks  and  cableways  from  being  laid  near  to  the  working-face. 

At  several  quarries  the  loading  into  the  cars  or  carts  is  accomplished 
by   means    of   steam-shovels.      The    cement    rock    seems    to    be   well 


FIG.  68. — Open  cut  in  cement  rock. 

adapted  for  handling  by  steam-shovels,  but  even  then  much  sledging 
is  necessary  and  the  blasting  operations  are  interfered  with. 

Cement  production  of  the  district. — The  importance  of  these  Lehigh 
district  cement-rock  deposits  is  well  brought  out  by  Table  154. 

Probable  extension  of  the  industry. — As  noted  in  the  earlier  portion 
of  this  chapter,  the  cement  deposits  have  been  developed  only  from  near 
Reading,  Pa.,  to  a  few  miles  west  of  Stewartsville,  N.  J.  Most  of  the 
readily  accessible  cement  land  between  these  points  has  been  taken 
up  by  the  cement  companies  or  is  being  held  at  impossible  prices  by 
the  owners.  Under  these  circumstances  it  seems  probable  that  few 
additional  plants  can  be  profitably  established  in  the  district  now 
developed,  and  that  the  growth  of  the  industry  here  will  be  brought 
about  by  extending  the  district.  A  few  notes  on  the  distribution  of 
the  same  cement-beds  in  adjoining  areas  may  therefore  be  of  interest 
to  those  desiring  to  engage  in  the  manufacture  of  Portland  cement 
from  materials  of  the  Lehigh  district  type. 


332 


CEMENTS,  LIMES,  AND   PLASTERS. 


TABLE  154. 
PORTLAND-CEMENT  PRODUCTION  OF  THE  LEHIGH  DISTRICT,  1890-1902. 


Year. 

Lehigh  District. 

Entire  United  States. 

Percentage  of 
Total  Product 
Manufactured 
in  Lehigh 
District. 

Number 
of  Plants. 

Number  of 
Barrels. 

Number 
of  Plants. 

Number  of 
Barrels. 

Value. 

1890.. 
1891 

5 
5 
5 
5 
7 
8 
8 
8 
9 
11 
15 
16 
17 
19 

201,000 
248,500 
280,840 
265,317 
485,329 
634,276 
1,048,154 
2,002,059 
2,674,304 
4,110,132 
6,153,629 
8,595,340 
10,829,922 
12,324,922 

-    16 
17 
16 
19 
24 
22 
26 
29 
31 
36 
50 
56 
65 
75 

^35,500 

'.  454,813 
547,440 
590,652 
798,757 
990,324 
1,543,023 
2,677,775 
3,692,284 
5,652,266 
8,482,020 
12,711,225 
17,230,644 
22,342,973 

$439,050 
1,067,429 
1,152,600 
1,158,138 
1,383,473 
1,586,830 
2,424,011 
4,315,891 
5,970,773 
8,074,371 
9,280,525 
12,532,360 
20,864,078 
27,713,319 

60.0 
54.7 
51.3 
44.9 
60.8 
64.0 
68.1 
74.8 
72.4 
72.7 
72.6 
67.7 
62.8 
55.2 

1892  

1893  

1894  

1895  
1896 

1897  .    . 

1898  .    . 

1899  

1900  

1901  

1902  

1903  

Northeast  of  Stewartsville,  N.  J.,  the  cement-beds  outcrop  at  fre- 
quent intervals  in  the  Kittatinny  Valley  all  the  way  across  New  Jersey 
and  a  few  miles  into  Orange  County,  N.  Y.  The  exact  locations  of 
these  deposits,  with  numerous  analyses  of  the  cement  rocks,  are  given 
in  the  Annual  Report  of  the  State  Geologist  of  New  Jersey  for  1900, 
pages  41-95.  Many  detailed  maps  in  this  report  show  the  outcrops 
very  precisely. 

Southwestward  from  Reading  the  Trenton  beds  outcrop  in  a  belt 
crossing  Lebanon,  Cumberland,  and  Franklin  counties,  Pa.,  passing 
near  the  tows  of  Lebanon,  Harrisburg,  Carlisle,  and  Chambersburg. 
In  Maryland  the  Trenton  rocks  occur  in  Washington  County,  while  in 
West  Virginia  and  Virginia  they  are  extensively  developed.  The  dis- 
tribution of  these  rocks  in  Virginia  is  discussed  in  the  papers  by  Messrs. 
Bassler  and  Catlett,  cited  in  the  list  on  page  333. 

Throughout  this  southern  extension  of  the  Lehigh  rocks,  the  Tren- 
ton is  not  everywhere  an  argillaceous  limestone,  but  it  is  frequently 
so,  and  it  is  always  very  low  in  magnesium  carbonate.  It  is  therefore 
probably  safe  to  say  that  in  southern  Pennsylvania,  Maryland,  West 
Virginia,  and  Virginia  the  Trenton  rocks  are  everywhere  good  Port- 
land-cenlent  materials,  though  in  some  cases  they  will  require  pure 
limestone,  and  in  other  places  clay,  to  bring  them  to  proper  composition. 

Cement  Rocks  in  Other  States. 

Limestones  sufficiently  clayey  to  be  called  "  cement  rocks"  are  not 
by  any  means  confined  to  the  Lehigh  district,  nor  even  to  the  imme- 


ARGILLACEOUS  LIMESTONE:  CEMENT  ROCK. 


333 


diate  vicinity  of  that  fortunate  area.  As  noted  in  the  last  chapter, 
cement  rock  exactly  similar  to  that  used  in  the  Lehigh  district  occurs 
in  other  parts  of  Pennsylvania,  in  Maryland,  and  the  Virginias.  Similar 
clayey  limestones  occur  southward,  along  the  Appalachian  Valley, 
through  Tennessee  and  northern  Georgia.  In  all  this  range,  however, 
they  have  never  been  used  as  Portland-cement  materials,  though  a 
natural-cement  plant  was  erected  a  few  years  ago  at  Rossville,  Ga.,  a 
few  miles  south  of  Chattanooga,  to  utilize  limestones  closely  similar  to 
the  Lehigh  rock  in  composition. 

The  following  analyses  show  the  composition  of  " cement  rocks" 
used  at  various  Portland-cement  plants  in  the  Western  States,  together 
with  that  of  the  purer  limestones  used  for  mixing. 

TABLE  155. 
ANALYSES  OF  "CEMENT-ROCK"  MATERIALS  FROM  THE  WESTERN  UNITED  STATES. 


Utah. 

California. 

Colorado. 

Cement 
Rock. 

Lime- 
stone. 

Cement 
Rock. 

Lime- 
stone. 

Cement 
Rock. 

Lime- 
stone. 

Silica  (SiO2)     

21.2 
8.0 

6.8 
3.0 

20.06 
10.07 
3.39 
63.40 
1.54 

7.12 
2.36 
1.16 
87.70 
0.84 

14.20 
5.21 
1.73 
75.10 
1.10 

88.0 

Alumina  (A12O3)  

Iron  oxide  (Fe2O3) 

Lime  carbonate  (CaCO3)         .  .  . 

62.08 
3.8 

89.8 
0.76 

Magnesium  carbonate  (MgCO3). 

In  addition  to  the  "cement  rocks"  noted  in  this  chapter,  it  is  neces- 
sary to  call  atention  to  the  fact  that  many  of  the  chalky  limestones 
discussed  in  the  following  chapter  are  sufficiently  argillaceous  to  be 
classed  as  " cement  rocks".  Because  of  their  softness,  however,  all 
these  chalky  limestones  will  be  described  together. 

List  of  references  on  "  cement  rock  ". 

Bassler,  P.  S.  Cement  materials  of  the  Valley  of  Virginia.  Bulletin  260, 
IT.  S.  Geol.  Survey,  pp.  531-544.  1905. 

Catlett,  C.  Cement  resources  of  the  Valley  of  Virginia.  Bulletin  225, 
U.  S.  Geol.  Survey,  pp.  457-461.  1904. 

Eckel,  E.  C.  Cement-rock  deposits  of  the  Lehigh  district  of  Pennsylvania  and 
New  Jersey.  Bulletin  225,  U.  S.  Geol.  Survey,  pp.  448-456.  1904. 

Eckel,  E.  C.  Cement  materials  and  cement  industries  of  the  United  States. 
Bulletin  243,  U.  S.  Geol.  Survey,  pp.  .  1905. 

Kiimmel,  H.  B.  Report  on  the  Portland-cement  industry  in  New  Jersey. 
Ann.  Rep.  N.  J.  State  Geologist  for  1900,  pp.  9-101. 

Peck,  F.  B.  The  cement-belt  of  Lehigh  and  Northampton  counties,  Pennsyl- 
vania. Mines  and  Minerals,  vol.  25,  pp.  53-57.  1904. 


CHAPTER  XXV. 

FRESH-WATER  MARLS. 

It 

MARLS,  in  the  sense  in  which  the  term  is  used  in  the  Portland-cement 
industry,  are  fine-grained,  friable  limestones  which  have  been  deposited 
in  the  basins  of  existing  or  extinct  lakes.  So  far  as  chemical  composi- 
tion is  concerned,  marls  are  practically  pure  limestones,  being  usually 
composed  almost  entirely  of  calcium  carbonate.  Physically,  however, 
they  differ  greatly  from  the  hard,  compact  rocks  to  which  the  term 
limestone  is  more  commonly  applied,  for  the  marls  are  granular,  loose, 
non-coherent  deposits.  These  curious  physical  characters  of  marls, 
as  compared  with  ordinary  limestones,  are  due  to  the  peculiar  condi- 
tions under  which  the  former  have  been  deposited.  Samples  of  marl 
from  different  localities  will  on  comparison  be  found  to  exhibit  consider- 
able variations,  and  these  arise  in  large  part  from  differences  in  local 
conditions  during  deposition. 

As  explained  on  a  later  page,  differences  of  opinion  exist  as  to  the 
exact  cause  of  the  formation  of  marl  deposits.  The  points  in  con- 
troversy are  of  no  particular  practical  importance,  and  may  be  dis- 
regarded in  the  present  brief  statement  of  facts.  It  may  safely  be 
said  that  marls  are  deposited  in  lakes  by  spring  or  stream  waters  carrying 
lime  carbonate  in  solution.  The  actual  deposition  of  the  marl  is  in 
part  due  to  purely  physical  and  chemical  causes,  and  in  part  to  the 
direct  or  indirect  action  of  animal  or  vegetable  life.  The  result  in 
any  case  is  that  a  calcareous  deposit  forms  along  the  sides  and  over 
the  bottom  of  the  lake,  this  deposit  consisting  of  lime  carbonate,  mostly 
in  a  finely  granular  form,  interspersed  with  shells  and  shell  fragments. 

Various  uses  of  the  term  "marl". — A  warning  to  the  reader  con- 
cerning other  uses  of  the  term  "marl"  may  profitably  be  introduced 
here.  The  meaning  above  given  is  that  in  which  the  term  marl  is  com- 
monly used  in  the  cement  industry  at  the  present  day.  But  in  geological 
and  agricultural  reports,  particularly  in  those  issued  before  the  Portland- 
cement  industry  became  prominent  in  this  country,  the  term  marl  has 
been  used  to  cover  several  very  different  substances.  The  following 

334 


FRESH-WATER  MARLS.  335 

three  uses  of  the  term  will  be  found  particularly  common,  and  must 
be  guarded  against  when  such  reports  are  being  examined  in  search 
for  descriptions  of  deposits  of  cement  materials. 

1.  In  early  days  the  terms  " marls"  and  " marly tes"  were  used  to 
describe   deposits    of   calcareous   shales — and   often   these   terms   were 
extended  to  cover  shales  which  were  not  particularly  calcareous.     This 
use  of  the  term  will  be  found  in  many  of  the  earlier  geological  reports 
issued  by  New  York,  Ohio,  and  other  interior  States. 

2.  In  New  Jersey  and  the  States  southward  bordering  on  the  Atlantic 
and   Gulf  of  Mexico  the  term   marl  is  commonly  applied  to  deposits 
of  soft  chalky  or  unconsolidated  limestone  often  containing  consider- 
able clayey  and  phosphatic  matter.     These  limestones  are  of  marine 
origin  and  not  related  to  the  fresh-water  marl  deposits  which  are  the 
subject  of  the  present  chapter. 

3.  In  the  same  States,  but  particularly  in  New  Jersey  and  Virginia,  large 
deposits  of  the  so-called  " green-sand  marls"  occur.     This  material  is  in 
no  way  related  to  the  true  marls  (which  are  essentially  lime  carbonates), 
but  consists  largely  of  the  iron  silicate  called  glauconite,  or  green  sand, 
with  very  small  percentages  of  clayey,  calcareous,  and  phosphatic  matter. 

The  three  early  uses  of  the  term  "marl"  above  noted  all  agree  in 
that  they  apply  to  deposits  of  marine  origin,  while  the  marls  of  the  cement 
manufacturer  are  purely  fresh-water  deposits. 

Occurrence  of  marl  deposits. — Fresh-water  marls  occur  in  more  or 
less  lenticular  or  basin-shaped  deposits  of  relatively  small  size.  Their 
form  and  local  character  are  both  due  to  the  fact  that  the  marls  were 
formed  by  deposition  in  lake  basins.  In  many  cases  these  lakes  still 
contain  water,  and  in  some  instances  marl  deposition  is  now  in  progress. 
In  other  cases,  however,  the  lake  has  entirely  disappeared,  and  the  marl- 
bed  now  occurs  in  a  swamp  or  marsh  covered  with  peat  or  muck. 

The  disappearance  of  a  lake  in  this  fashion  must  be  regarded  as  part 
of  a  very  natural  and  almost  invariable  cycle  of  events.  The  existence 
of  a  lake  at  any  point  along  a  drainage  system  is  to  be  considered  a 
somewhat  unnatural  and  temporary  condition,  and  one  which  will  be 
removed  by  natural  causes  as  soon  as  possible.  In  the  glaciated 
portion  of  the  United  States  many  lakes  were  formed  at  the  close  of 
the  Glacial  period.  These  lakes  were  due  in  some  cases  to  the  fact  that 
deposits  of  sand  and  clay  laid  down  by  the  glaciers  had  filled  old 
valleys  and  dammed  the  streams  occupying  such  valleys.  In  other  cases 
the  lake  basins  were  formed  by  the  irregular  distribution  of  these  glacial 
deposits,  leaving  hollows  and  depressions  which  subsequently  became 
•illed  with  water.  In  either  case  a  lake  or  pond  was  formed,  and  imme- 


336  CEMENTS,  LIMES,  AND  PLASTERS. 

diately  a  series  of  natural  forces  were  set  in  operation  which  tended 
to  remove  this  lake.  Of  the  two  common  methods  of  lake  disappearance, 
one  has  but  little  to  do  with  our  present  subject,  but  the  other  is  closely 
connected  with  the  history  of  marl  deposition.  The  first  method  is 
the  gradual  deepening  of  the  outlet  by  the  action  of  its  own  current, 
resulting  in  the  draining  of. .the  lake.  The  second  is  the  filling  up  of 
the  lake  basin  by  deposits  of  sand,  cla$,  marl,  muck,  and  .peat. 

Origin  of  marl  deposits. — The  exact  cause  of  the  formation  of  marl 
deposits  has  been  the  subject  of  much  investigation  and  discussion, 
particularly  in  the  past  few  years,  since  these  deposits  have  become 
of  so  great  economic, importance.  For  details  concerning  this  dis- 
cussion, reference  should  be  made  to  the  papers  listed  on  pages  34G-347, 
especially  to  those  by  Davis  and  Blatchley.  In  the  present  place  only 
a  summary  of  the  main  facts — and  theories — in  regard  to  the  forma- 
tion of  marl  deposits  will  be  given. 

Marl  deposits  in  their  present  form  and  position  are  due  directly 
or  indirectly  to  glacial  action,  on  which  account  these  deposits  occur 
almost  exclusively  in  that  portion  of  the  country  which  was  covered 
by  ice  during  the  Glacial  epoch.  The  glaciers  aided  in  the  formation 
of  marl  deposits  in  two  ways:  first,  by  furnishing  a  large  supply  of 
finely  ground  calcareous  material  from  which  surface  waters  could 
take  up  lime  carbonate  in  solution,  and,  second,  by  forming  the  lake 
basins  in  which  these  waters  deposited  their  burden  of  lime  carbonate 
as  marl.  The  processes  followed  in  the  formation  of  marl  deposits 
may  be  outlined  with  some  confidence,  though  certain  of  the  steps  are 
still  subject  to  discussion. 

Rain-water,  though  theoretically  pure  before  approaching  the  earth's 
surface,  takes  up  a  considerable  percentage  of  carbon  dioxide  in  pass- 
ing through  the  atmosphere.  When  it  reaches  the  surface,  therefore, 
such  rain-water  is  in  reality  a  very  dilute  form  of  carbonic  acid  (H^COs), 
and  as  such  is  capable  of  attacking  limestone,  taking  the  lime  car- 
bonate (CaCO3)  into  solution  in  the  form  of  calcium  bicarbonate 
(CaH2(CO3)2).  Practically  all  natural  water,  including  the  percolat- 
ing ground-water  as  well  as  spring  and  stream  water,  is  therefore  able 
to  change  itself  with  lime  carbonate  if  some  source  of  that  compound 
presents  itself.  In  the  present  marl  districts  such  a  source  is  not  far 
to  seek,  for  from  New  York  to  Michigan  limestones  cover  a  large  pro- 
portion of  the  surface.  The  glaciers  during  their  advance  over  this 
area  ground  up  vast  quantities  of  the  surface  rocks,  leaving  the  pul- 
verized debris  in  the  form  of  deposits  of  limey  gravels  and  limey  clays. 

Surface  waters  running  through  such  areas,  or  underground  waters 


FRESH-WATER  MARLS.  337 

percolating  through  beds  of  limestone  or  coarse  limey  clays,  will,  if 
charged  with  carbon  dioxide,  dissolve  and  carry  off  lime  carbonate, 
the  exact  amount  so  dissolved  being  determined  by  the  percentage 
of  CO2  contained  in  the  water,  its  temperature,  etc.  The  tendency  is 
for  every  water  to  charge  itself  with  its  maximum  possible  amount 
of  calcium  bicarbonate,  and  until  it  is  so  charged  it  will  continue  to 
attack  and  dissolve  limestones  which  it  encounters  in  its  course. 

When  the  water  is  almost  or  quite  saturated  with  calcium  bicar- 
bonate, any  increase  in  temperature  or  decrease  in  pressure  will  cause 
the  deposition  of  lime  carbonate.  Reactions  of  this  type  have  been 
appealed  to  as  explanations  of  the  formation  of  marl  deposits  through 
the  warming  or  loss  of  pressure  which  occurs  when  spring^  or  stream 
water  enters  a  lake.  A  recent  statement  *  of  this  theory  is  as  follows: 

"This  spring-water  as  it  enters  the  lake  is  always  colder  than  the 
waters  of  the  lake  itself.  The  bicarbonate  of  lime  is  more  soluble  in 
cold  water  than  in  warm  and  a  part  of  the  dissolved  material  is  there- 
fore precipitated  in  the  form  of  a  fine  powder  soon  after  the  cold  stream 
enters  the  warmer,  still  water  of  the  lake.  Such  precipitation  of  cal- 
cium carbonate  from  cold  water  as  it  becomes  warm  is  seen  every  day 
in  almost  every  household.  The  hard  water  heated  in  tea-kettles  holds 
while  cold  a  large  quantity  of  bicarbonate  of  lime  in  solution.  As  it 
becomes  warm,  much,  if  not  all,  of  this  falls  and  forms  a  coating  of 
lime  carbonate  upon  the  bottom  of  the  kettle. 

"  Again,  if  there  is  a  large  amount  of  carbon  dioxide  in  the  perco- 
lating waters  the  percentage  of  carbonate  of  lime  held  in  solution  will 
be  increased  in  proportion.  As  the  spring-water  enters  the  lake  and 
rises  to  the  surface  the  pressure  will  be  decreased  and  a  part  of  the 
carbon  dioxide  will  escape  and  so  cause  a  precipitation  of  another  part 
of  the  carbonate  of  lime  according  to  the  following  formula: 

"CaH2(CO3)2-CO2  =  CaCO3+H2O." 

In  support  of  his  belief  that  the  formation  of  most  marl  deposits 
is  due  to  the  two  causes  above  outlined,  Blatchley  urges  that  most,  if 
not  all,  of  the  marl  lakes  examined  in  Indiana  are  fed  by  subterranean 
or  subaqueous  springs,  even  though  they  also  have  streams  entering 
and  leaving  them,  and  that  "the  larger  deposits  of  marl  in  the  lakes 
are  found  in  close  proximity  to  these  springs  ". 

Davis,  in  studying  the  Michigan  marls,  came  to  the  conclusion  that 
the  causes  above  noted  would  not  of  themselves  account  for  the 

*  Blatchley,  W.  S.     25th  Ann.  Rep.  Indiana  Dept.  Geology,  p.  45. 


338  CEMENTS,  LIMES,  AND  PLASTERS. 

majority  of  marl  deposits.  His  studies  *  led  him  to  believe  that  more 
important  effects  were  due  to  the  action  of  certain  aquatic  plants  of 
low  type,  notably  Char  a  (sonewort)  and  Zonotrichia,  another  alga. 
Plants  of  higher  type  are  also  influential  in  marl  deposition,  but  to  a 
less  degree.  Davis  has  summarized  f  his  views  as  follows : 

-'All  green  plants,  whether  aquatic  or  terrestrial,  take  in  the  gas 
(carbon  dioxide)  through  their  leaves^  and  stems  and  build  the  carbon 
atoms  and  part  of  the  oxygen  atoms  of  which  the  gas  is  composed  into 
the  new  compounds  of  their  own  tissues,  in  the  process  releasing  the 
remainder  of  the  oxygen  atoms.  Admitting  these^facts,  we  have  two 
possible  general  causes  for  the  formation  of  the  incrustation  (of  cal- 
cium carbonate)  upon  all  aquatic  plants.  If  the  calcium  and  other 
salts  are  in  excess  in  the  water,  and  are  held  in  solution  by  free  carbon 
dioxide,  then  the  more  or  less  complete  abstraction  of  that  gas  from 
the  water  in  direct  contact  with  plants  causes  precipitation  of  the  (lime) 
salts  upon  the  parts  abstracting  the  gas,  namely,  the  stems  and  leaves. 
But  in  water  containing  the  salts,  especially  calcium  bicarbonate,  in 
amounts  so  small  that  they  would  not  be  precipitated  if  there  were 
no  free  carbon  dioxide  present  in  the  water  at  all,  the  precipitation 
may  be  considered  a  purely  chemical  problem,  a  solution  of  which  may 
be  looked  for  in  the  action,  upon  the  bicarbonates,  of  the  oxygen  set 
free  by  the  plants.  Of  these  bicarbonates,  calcium  bicarbonate  is  the 
most  abundant,  and  the  reaction  upon  it  may  be  taken  as  typical  and 
expressed  by  the  following  chemical  equation: 

CaH2(CO3)2   +    0  =      CaCO3       +       C02      4-H2O+    O, 

Calcium  bicarbonate  +  oxygen  =  calcium  carbonate  +  carbon  dioxide  +  water  +  oxygen 

in  which  the  calcium  bicarbonate  is  converted  into  the  normal  (and  very 
slightly  soluble)  carbonate  by  the  oxygen  liberated  by  the  plants,  and 
both  carbon  dioxide  and  oxygen  are  set  free,  the  free  oxygen  possibly 
acting  still  further  to  precipitate  calcium  monocarbonate.  It  is  probable 
that  the  plants  actually  do  precipitate  calcium  carbonate  in  both  these 
ways  (i.e.,  by  abstracting  carbon  dioxide  from  the  water  and  by  freeing 
oxygen),  but  in  water  containing  relatively  small  amounts  of  calcium 
bicarbonate  the  latter  would  seem  to  be  the  probable  method." 

Professor  Davis  has  further  proven  that  Cham  acts  in  still  a  third 
way,  abstracting  lime  salts  directly  from  the  water  as  part  of  its  life 
processes  and  depositing  them  in  its  tissues. 

*  See  papers  by  Davis,  cited  in  list  on  pp.  346-347. 
f  Vol.  8,  pt.  3,  Reports  Michigan  Geol.  Survey,  p.  69. 


FRESH-WATER  MARLS.  339 

A  further  possible  mode  of  derivation,  which  is  admittedly  the  way 
in  which  part  of  all  the  marl  deposits  have  originated,  is  through  the 
direct  action  of  molluscs.  These  animals  are  especially  frequent  in  limey 
waters  and  have  the  power  of  abstracting  lime  salts  from  the  water 
and  utilizing  the  resulting  lime  carbonate  in  the  formation  of  their 
shells.  On  the  death  of  the  animals  their  shells  sink  to  the  bottom 
and  form  an  essential  portion  of  any  deposit  which  is  in  process  of  forma- 
tion. In  some  marl-beds  shells  amount  to  an  impoitant  percentage  of 
the  total,  but  in  most  cases  they  will  probably  constitute  less  than  5  per 
cent  of  the  entire  mass. 

The  facts  so  far  stated  may  be  summaiized  as  follows:  Spring  or 
stream  water,  carrying  lime  carbonate  in  solution,  Deposits  it  in  lakes 
in  the  form  of  marl,  this  deposition  being  caused  by: 

(a)  Escape  of  carbon  dioxide,  owing  to  decrease  in  pressure; 
(6)  Supersaturation,  owing  to  rise  in  temperature; 

(c)  Abstraction  of  carbon  dioxide  by  plants; 

(d)  Freeing  of  oxygen  by  plants,  resulting  in  formation  of  carbon- 

ates from  bicarbonates  ; 

(e)  Direct  abstraction  and  crystallization  of  lime  salts  by  Chara. 

(f)  Abstraction  of  limeby  molluscs  and  formation  of  shell  deposits. 

The  formation  of  a  given  marl-bed  may  be  due  to  the  operation  of 
any  one  of  these  causes,  or  the  cooperation  of  two  or  more  of  them. 

Geographic  distribution  of  marl  deposits. — The  geographic  dis- 
tribution of  marl  deposits  is  intimately  related  to  the  geologic  history 
of 'the  region  in  which  they  occur.  Marl-beds  are,  as  indicated  in  the 
preceding  section,  the  result  of  the  filling  of  old  lake  basins.  Lakes 
are  not  common  except  in  those  portions  of  the  United  States  which 
were  affected  by  glacial  action,  since  lakes  are  in  general  due  to  the 
damming  of  streams  by  glacial  material  or  to  irregularities  in  deposition 
of  such  material.  Workable  marl  deposits,  therefore,  are  almost  ex- 
clusively confined  to  those  portions  of  the  Unit  d  States  and  Ganada 
lying  north  of  the  former  southern  limit  of  the  glaciers. 

Marl-bed^  are  found  in  the  New  England  States,  where,  however, 
they  are  seldom  of  important  size,  and  in  New  York,  large  beds  occurring 
in  the  central  and  western  portions  of  that  State.  Deposits  are  frequent 
and  important  in  Michigan,  and  in  the  northern  portions  of  Ohio,  In- 
diana, and  Illinois.  Marl-beds  occur  in  Iowa,  Wisconsin,  and  Minnesota, 
but  have  not  been  as  yet  exploited  for  cement-manufacture.  Extensive 
marl-beds  also  occur  in  Ontario,  Quebec,  and  other  Canadian  prov- 
inces. 


340 


CEMENTS,  LIMES,  AND  PLASTERS. 


Physical  characters  of  marl. — Marl  as  found  in  existing  lakes  may 
contain  as  high  as  50  per  cent  of  water,  while  even  the  dry  marl-beds 
occurring  in  swamps  or  marshes  will  carry  15  to  25  per  cent  of  moisture. 
This  moisture,  together  with  the  fine  granular  character  of  the  marl 
itself,  gives  it  a  sticky,  putty-like  character.  In  color  pure  marl  is 
white,  but  it  usually  contains  so  much  organic  matter  as  to  give  even 
the  better  samples  a  grayish'  or  yellowish  tint,  while  the  more  impure 
marls  may  be  very  dark  gray  in  color. 

Marl  usually  contains  very  little  sand  or  grit,  though  some  of  its 
shells  and  lime  carbonate  particles  may  give  it  a*- gritty  feeling  when 
examined.  Such  shells,  etc.,  can,  however,  be  usually  crushed  between 
the  fingers,  which  will  serve  to  distinguish  them  in  the  field  from  sand 
grains.  Though  as  sticky  as  clay,  marl  is  markedly  lighter  in  weight, 
owing  to  the  high  percentage  of  moisture  which  it  contains. 

The  natural  fineness  of  marl  is  a  matter  which  is  of  direct  interest 
to  the  Portland-cement  manufacturer,  because  of  its  effect  on  the 
cost  of  grinding  the  raw  material.  Marls  differ  quite  widely  in  this  regard, 
some  being  fine-grained  throughout,  while  others  contain  considerable 
percentages  of  coarse  material,  including  shells,  etc. 

The  sieving  tests  tabulated  below  *  were  carried  out  by  Prof.  Davis 
on  samples  of  marl  from  three  Michigan  localities,  and  serve  to  show 
the  differences  in  fineness  above  noted. 

TABLE  156. 
FINENESS  OF  CRUDE  MARL.     (DAVIS.) 


1. 

2. 

3. 

Residue  on 

it        it 

ti        1  1 
tt        1  1 
it        tt 

Passing 

20-mesh  sieve 

Per  Cent. 
32.25 
6.06 
7.58 
2.90 
4.81 
46.40 

Per  Cent. 
31.52 
14.48 
12.76 
2.56 
6.74 
31.94 

Per  Cent, 
0.36 
3.53 
6.51 
3.34 
6.44 
79.82 

40-      '    •      '•   

60-     '          '    

80-     '          '    

100-     '          ' 

100-     '          ' 

1.  Cedar  Lake. 

2.  Littlefield  Lake. 

3.  Michigan  P.  C.  Co.,  Cold  water. 

The  weight  of  the  marl  is  also  a  matter  of  economic  interest.  A 
wet  marl,  as  dredged  from  a  lake  bottom  carrying  from  50  to  60  per  cent  of 
water,  may  average  about  2000  Ibs.  per  cubic  yard,  so  that  a  cubic  yard 
of  such  material  would  contain  only  about  800  to  1000  Ibs.  dry  marl. 
A  dry  marl  taken  from  a  well-drained  marsh  or  swamp  may  run  as 


*  Vol.  8,  pt.  3,  Reports  Michigan  Geol.  Survey,  pp.  74-77. 


FRESH-WATER  MARLS.  341 

low  as  20  per  cent  of  water.  Such  a  marl  would  then  weigh  about 
2600  Ibs.  per  cubic  yard,  and  a  cubic  yard  would  contain  about  a  ton 
of  pure  marl. 

In  dealing  with  the  wet  marls  a  cement-plant  may  produce  from 
one  and  a  half  to  three  barrels  of  cement  from  each  cubic  yard  of  marl, 
while  a  marsh  marl  might  yield  four  barrels  cement  per  cubic  yard. 
In  estimating  the  life  of  a  lake  marl  deposit  it  will  be  safest  to  assume 
that  each  cubic  yard  of  marl  in  place  will  produce  only  two  barrels  of 
cement. 

Chemical  composition  of  marl. — Marl  itself,  being  a  chemical  deposit, 
is  almost  a  pure  carbonate  of  lime.  During  and  after  its  deposition,  how- 
ever, foreign  matter  of  various  kinds  is  apt  to  get  mixed  in  with  the 
marl,  the  principal  impurities  thus  introduced  being  fine  sand,  clayey 
matter,  and  organic  material.  Of  these  the  most  important,  from  the 
cement  manufacturer's  point  of  view,  is  the  organic  matter. 

Sand  is  rarely  present  in  sufficient  amount  to  render  the  marl  unser- 
viceable, and  of  the  2  or  3  per  cent  of  sand  shown  by  most  marls  some 
is  fine  enough  to  pass  a  150-mesh  sieve  and  will  therefore  enter  into 
combination  in  the  kiln.  The  clay  present  in  marls  is  principally  objec- 
tionable because  of  its  tendency  to  increase  the  percentage  of  magnesia 
and  sulphur  trioxide. 

Organic  matter  burns  out  in  the  kiln  and  might  therefore  be  regarded 
as  a  harmless  impurity.  But  a  high  percentage  of  it  in  a  marl  is  in  reality 
very  objectiona'ble,  both  negatively,  because  it  lowers  the  percentage 
of  lime  carbonate  in  the  marl,  and  positively,  because  it  retains  moisture 
with  great  avidity.  It  is  almost  impossible  to  dry  a  marl  containing 
much  organic  matter,  and  in  any  semi-dry  or  dry  process  this  would 
be  a  very  serious  disadvantage.  Organic  matter  in  its  coarser  forms 
— i.e.,  roots,  branches,  twigs,  etc.,  interferes  greatly  with  the  grinding 
of  the  marl,  though  the  larger  fragments  are  usually  taken  out  by  a 
separator  early  in  the  reducing  process. 

In  the  following  table  (157)  are  given  the  analyses  of  marls  used  at 
different  American  cement-plants,  some  quoted  from  published  sources 
and  others  supplied  by  the  chemists  of  the  plants.  A  few  of  the  quoted 
analyses  are  taken  from  prospectuses,  but  in  general  the  analyses  are 
of  more  satisfactory  character.  In  all  cases  they  are  calculated  dry, 
all  water  below  212°  being  neglected. 

The  analyses  given  in  this  table  are  mostly  not  picked  analyses, 
such  as  are  usually  quoted  in  prospectuses,  in  which  the  marl  rarely 
carries  less  than  98  per  cent  of  lime  carbonate.  On  the  other  hand, 
some  of  them  are  still  considerably  better  than  can  be  expected 


342 


CEMENTS,  LIMES,  AND  PLASTERS. 


TABLE  157, 
ANALYSES  OF  MARLS  USED  IN  AMERICAN  CEMENT-PLANTS. 


Silica 
(Si02). 

Alu- 
mina 
(AlsOs). 

Iron 
Oxide 
(Fe203). 

Lime 
(CaO). 

Magnesia 
(MgO). 

Alkalies 

(S&,. 

Sulphur 

oxide 
(S03). 

Carbon 
Dioxide 
(COaJ. 

Organic 
Matter. 

1 

2 
3 
4 
5 

6 
7 
•    '8 
9 
10 
11 
12 
13 
14 
15 
10 
17 
18 
19 
20 
21 
22 
23 
24 
25 
26 

1.74 

1.78 
0.85 
0.66 
3.80 
0.19 
0.22 
0.77 
1.24 
0.72 
0.06 
1.19 
1.20 
n.  d. 

0.90 
1. 
0. 
0. 
n. 
0.05 
0. 
0. 
0. 
0.24 
0. 
0.55 
0.55 
n.  d. 

0.28 
21 
86 
62 
d. 
0.07 
76 
11 
80 
0.12 
80 
0.25 
0.40 
n.  d 

49.84 
49.55 
51.04 
53  .  17 
51.10 
51.31 
51.56 
53.58 
50.90 
55.12 
55.00 
52.50 
51.15 
51.90 
50.77 
53.50 
52.30 
52.80 
50.98 
47.86 
53.16 
54.40 
50.95 
52.86 
50.62 
54.44 

l.ft 

1.30 
1.31 
0.47 
1.54 
1.93 
1.26 
0.91 
1.43 
0.44 

lYl*6 
0.37 
0.83 
tr. 
0.3 
1.01 
0.18 
0.19 
0.04 
1.50 
2.34 
0.55 
n.  d. 
2.09 
0.30 

:::: 

1.12 
1.58 

46. 
40.35 

42.35 

41.82 
42.40 
46. 
43.14 
41.54 
43.77 
43.22 
42.51 
40.59 
41.67 
39.89 

42.26 
41.73 
40.26 
42.11 

42.20 
40.03 

45. 
43.10 

01 
4.23 

2.53 
1.50 
2.25 
2C 

4.09 

n.  d. 
n.  d. 
n.  d. 
n.  d. 

0.86 
1.54 

1.68 

0.25 

58 
1.12 

.... 

G\24. 
0.14 

i.'si 

5.79 
n.  d. 
n.  d. 

tr. 
0.05 
tr. 
0.26 
0.20 
0.66 
1.7 
2.01 

1.65 
0.4 
0.42 
0.26 
0.26 
6.22 
0.14 
0.54 
1.98 
0.26 
1.43 
0.46 

0. 
0.2 

1. 
0. 
0.21  I 
1.70  1 
0. 
0. 
0. 
0. 
0.20  | 
0. 

81 
0.2 
C8 
10 
0.01 
0.86 
36 
56 
97 
20 
0.18 
44 

2.20 



0.12 

0.10 

1-2.  Sandusky  P.  C.  Co.,  Syracuse,  Ind.     S.  B.  Newberry,  analyst.     25th  Ann.  Rep.  Indiana 
Dept.  Geology,  p.  29,  182. 

3.  W abash  P.  C.  Co.,  Stroh,  Ind.     W.  R.  Oglesby,  analyst.     25th  Ann.  Rep.  Indiana  Dept. 

Geology,  p.  112. 

4.  Wabash  P.  C.  Co.,  Stroh,  Ind. 

5.  Millens  P.  C.  Works,  South  Bend,  Ind.     H.  H.  Hooper,  analyst.     25th  Ann.  Rep.  Indiana 

Dept.  Geology,  p.  25. 

6.  Millens  P.  C.  Works,  South  Bend,  Ind.       W.  A.  Noyes,  anaylst.      25th  Ann.  Rep.  Indiana 

Dept.  Geology,  p.  273. 

7.  Peninsular  P.  C.  Co.,  Cement  City,  Mich.     J.  G.  Dean,  analyst.     Vol.  8,  Mich.  Geol.  Survey, 

p.  236. 

8.  Newaygo  P.  C.  Co,  Newaygo,  Mich.      Lathbury  and  Spackman,  analysts.     Manufacturer's 

prospectus. 

9.  Newaygo  P.  C.  Co.,  Newaygo,  Mich.     Vol.  8,  Mich.  Geol.  Survey,  p.  240. 

10.  Allerman,  analyst.     Manufacturer's  prospectus. 

12-13.  Wolverine  P.  C.  Co.,  Coldwater,  Mich.     H.  E.  Brown,  analyst.     Vol.  8,  Mich.  Geol.  Survey, 
p.  247. 

14.  Wolverine  P.  C.  Co.,  Coldwater,  Mich.     "Cement  Industry",  p.  78. 

15.  Bronson  P.  C.  Co.,  Bronson,  Mich.     Mineral  Industry,  vol.  6,  p.  99. 

16.  Iroquois  P.  C.  Co.,  Caledonia,  N.  Y.     22d  Ann.  Rep.  N.  Y.  State  Geologist. 

17.  Millens  P.  C.  Works,  Wayland,  N.  Y. 
18-19.   Empire  P.  C.  Co.,  Warners,  N.  Y. 

20.  Montezuma,  N.  Y.     First  marl  used  for  cement.     Mineral  Industry,  vol.  1,  p.  52. 

21.  American  C.  Co.,  Jordan,  N.  Y. 

22.  Genesee  Wayland  P.  C.  Co.,  Perkinsville,  N.  Y. 

23.  Buckeye  P.  C.  Co.,  Harper,  Ohio.     Mineral  Industry,  vol.  1,  p.  52. 

24.  Castalia  P.  C.  Co.,  Castalia,  Ohio. 

25.  Imperial  P.  C.  Co.,  Owen  Sound,  Ontario. 

26.  Canadian  P.  C.  Co.,  Marlbank,  Ontario.     Rep.  Ontario  Bureau  Mines,  1901,  p.  16. 


FRESH-WATER  MARLS.  343 

in  steady  practice.  The  following  data  may  throw  some  light  on  what 
sort  of  results  are  really  obtained  when  a  marl  deposit  is  worked  con- 
tinuously. 

.First,  as  to  water  percentages:  At  a  Michigan  plant  which  takes 
its  marl  from  under  about  10  feet  of  water,  an  average  of  ten  con- 
secutive analyses  gave  the  following  results. 

Silica  (SiO2) 0.07 

Alumina  (A12O3) 1  Q  lg 

Iron  oxide  (Fe2O3) / 

Lime  carbonate  (CaCO3) 39.80  (  =  CaO  22.29%) 

Organic  matter 0 . 59 

Water 59.36 

The  marl  in  question  is,  it  will  be  noted,  very  pure,  being  low  in 
both  clay  and  organic  matter.  The  point  to  be  noted  is  the  high  per- 
centage of  water,  each  100  Ibs.  of  material  dredged  containing  approxi- 
mately only  40  Ibs.  of  lime  carbonate,  with  60  Ibs.  of  water.  It  must 
be  borne  in  mind  that  this  marl  was  not  pumped  to  the  plant,  so  that 
this  large  percentage  of  water  represents  only  what  was  unavoidably 
taken  up  with  the  marl  during  dredging. 

Second,  as  to  purity:  A  long  series  of  analyses  of  marl  at  another 
prominent  Michigan  plant  gave  the  following  limits  of  results.  These 
are  calculated  on  a  dry  basis,  the  55  per  cent  or  so  of  water  which  the 
marl  carried  when  reaching  the  plant  being  neglected. 

Silica  (SiO2) 1.40  to    8.60 


Alumina  (A12O3) 0.55 

Iron  oxide  (Fe2O3) 0 .25 

Lime  (CaO) 54. 60 

Magnesia  (MgO) 1 .25 

Carbon  dioxide  (CO2) 42.90 

Organic  matter 0 . 05 


1.30 
1.54 

46.20 

2.78 

36.30 

10.50 


It  will  be  seen  from  these  results  that  the  manager  should  expect  to 
receive  material  carrying  often  very  high  percentages  of  water  and 
frequently  containing  a  large  amount  of  organic  matter  and  other  im- 
purities. 

Examining  marl  deposits. — Owing  to  the  nature  of  the  material 
and  the  physical  conditions  under  which  it  occurs,  the  work  of  examin- 
ing and  valuing  a  marl  deposit  presents  certain  features  of  difficulty 
peculiar  to  itself.  As  in  any  other  prospecting  work,  the  two  factors 
which  require  determination  are  respectively  the  extent  of  the  deposit 
and  the  composition  of  the  material. 


344  CEMENTS,  LIMES,  AND  PLASTERS. 

When  the  marl  occurs  in  an  old  lake-bed  overlain  by  soil  or  peat,  the 
area  can  be  roughly  laid  out  into  blocks  or  squares  of  convenient  size, 
borings  being  made  and  samples  taken  at  the  corners  of  these  squares.  A 
pocket  compass,  or,  better  yet,  the  cheap  " drainage  level"  made  t>y 
Gurley  and  other  instrument-makers,  will  suffice  for  laying  out  the  work. 

A  marl  deposit  covered  by  water  must  be  handled  like  any  sound- 
ing proposition.  The  shore  line  should*first  be  roughly  surveyed,  after 
which  soundings  and  borings  must  be  made  from  a  raft  or  boat,  the 
position  of  each  boring  being  located  by  bearings  taken  to  fixed  points 
in  the  shore.  A  broad  steady  platform  is  necessary  for  the  borings. 
This  is  afforded  either  by  using  a  raft  with  a  square  opening  in  its  center 
or  by  laying  planks  across  the  ends  of  two  boats. 

As  the  methods  employed  in  determining  the  thickness  and  char- 
acter of  marl-beds  are  of  a  somewhat  special  character  and  are  not 
fully  described  in  current  engineering  text-books,  the  writer  feels  justified 
in  introducing  here  a  very  detailed  account  of  these  methods  by  Mr. 
David  J.  Hale,  of  the  Michigan  Geological  Survey.  This  account  is 
taken  almost  verbatim  from  the  paper  cited  below.* 

In  dealing  with  fairly  solid  marls  not  deeply  covered  with  peat 
or  soil,  the  simple  outfit  described  below  has  proven  very  successful 
when  manipulated  with  care.  It  is  prepared  as  follows: 

Weld  an  ordinary  2-inch  auger  on  a  f-inch  gas-pipe  2  feet  long. 
Thread  the  unwelded  end  of  the  pipe  for  coupling.  Cut  three  lengths 
of  pipe  each  in  half  or  in  four  pieces  if  it  is  desired  to  carry  the  outfit 
long  distances.  Thread  the  ends  of  these  sections  for  coupling.  Get 
couplings  enough  to  couple  all  together,  so  as  to  make  a  continuous 
hollow  rod  with  attached  auger.  Insert  a  "T"  coupling  on  the  handle 
end,  or  end  farthest  from  the  auger,  and  pass  a  rod  or  stick  through 
this  so  as  to  turn  the  outfit.  A  better  way  is  to  screw  into  each  free 
end  of  the  "T"  a  rod  or  piece  of  gas-pipe  18  inches  long.  Usually  a 
pair  of  Stillson  wrenches  are  needed  to  untwist  the  pipe,  which  becomes 
jammed  during  the  boring. 

Three-eighths-inch  pipe,  as  above  recommended,  will  be  found  to  lift 
out  much  easier  than  half-inch,  but  will  not  do  for  deep  borings-inch  pipe 
is  entirely  too  light  and  1-inch  pipe  is  too  difficult  to  handle.  A  light, 
easily  handled  outfit  is  a  great  aid  in  boring,  because  the  quicker  the  rod 
can  be  driven  the  less  friction  there  will  be  to  contend  with,  for  the  marl 
particles  will  not  have  time  to  settle  after  each  movement  of  the  rod. 


*  Hale,  D.  J.     The  use  of  marl  for  cement  manufacture.     Vol.  8,  pt.  3,  Reports 
Mich.  Geol.  Survey,  especially  pp.  9-13,  108-110. 


FRESH-WATER  MARLS.  345 

In  boring,  the  handle  should  be  twisted  around  as  the  rod  is  shoved 
down,  even  though  the  surface  material  may  be  soft  enough  to  permit 
it  to  be  driven  down  without  twisting,  because  if  the  latter  method  is 
adopted  the  surface  material  first  taken  up  by  the  auger  will  cling  to 
it  during  its  descent,  and  will  prevent  securing  a  sample  of  the  marl 
at  lower  depth.  As  each  new  length  of  pipe  is  added,  the  couplings 
should  be  firmly  tightened,  as  neglect  of  this  precaution  may  mean 
the  loss  of  most  of  the  outfit  through  uncoupling  while  it  is  being 
drawn  up. 

This  device  gives  good  results  when  employed  on  a  fairly  dense  marl 
not  deeply  covered  by  peat  or  grass,  because  the  auger  will  clear  itself 
of  the  surface  material  on  the  way  down  and  will  retain  fairly  well  the 
clean  sample  taken  at  the  bottom. 

In  heavily  covered  marl-beds,  or  in  dealing  with  very  fluid  marls, 
other  boring  devices  must  be  tried.  A  clumsy  but  efficient  type  of 
sampler  for  this  purpose  is  made  as  follows:  Take  a  2-foot  length  of 
1-inch  gas-pipe  and  thread  one  end  for  coupling.  Screw  reducers  on  the 
coupled  end  until  the  last  reducer  can  take  a  f-inch  or  J-inch  pipe, 
any  necessary  number  of  lengths  of  which  pipe  will  form  the  rod  proper. 
Sharpen  the  open  edge  of  the  1-inch  pipe  and  fit  into  it  a  plug  with  a 
shoulder  that  fits  against  the  rim,  allowing  the  plug  to  penetrate '  J  inch 
into  the  open  end  of  the  pipe.  Sharpen  the  end  of  the  plug  opposite 
the  shoulder  and  bore  a  hole  lengthwise  through  the  plug.  Pass  a 
&-inch  iron  rod  through  the  plug  from  the  shoulder  end  and  bolt  it  by 
screwing  a  nut  upon  the  end  opposite  the  shoulder,  which  end  should  be 
sharpened  so  as  to  penetrate  the  marl  more  easily.  The  end  of  the  rod 
may  be  threaded  for  several  inches  and  a  nut  screwed  on,  then  pass  the 
end  of  the  rod  through  the  plug  and  screw  the  nut  tight  against  the  plug. 
This  will  hold  the  plug  in  place  during  boring  and  withdrawing.  The 
rod  is  inserted  in  the  1-inch  pipe  and  passed  up  through*  that  and  the 
f-inch  pipe,  from  the  upper  end  of  which  the  free  end  of  the  rod  may 
project.  The  rod  gives  a  means  of  either  closing  firmly  or  opening  the 
bottom  end  of  the  1-inch  pipe.  When  boring,  the  plug  is  held  firmly 
against  the  mouth  of  the  pipe  by  means  of  the  rod,  and  the  whole  appara- 
tus is  shoved  down  into  the  marl  to  the  desired  depth.  The  pipe  is  then 
raised,  while  the  rod  is  held  stationary;  the  apparatus  is  held  in  this 
position  a  moment  to  allow  the  marl  to  close  in  about  the  rod  and  then 
the  pipe  is  lowered  until  the  plug  closes  it.  With  the  plug  held  firmly 
the  entire  apparatus  is  raised  to  the  surface,  the  plug  loosened,  and  the 
sample  of  marl  taken  out  of  the  section  of  1-inch  pipe.  This  device  can 
be  driven  through  and  withdrawn  from  a  marl-bed  covered  by  peat, 


346  CEMENTS,  LIMES,  AND   PLASTERS. 

grass,  etc.,  and  still  the  marl  sample  can  be  preserved  from  intermixture 
with  these  materials. 

A  borer  invented  and  manufactured  by  Robert  G.  Hunt  &  Co.  is  also 
noted  by  Mr.  Hale.  This  consists  of  a  piece  of  steel  about  18  feet 
long,  much  the  shape  of  the  half  of  a  long  gun-barrel  split  longitudinally. 
The  end  which  first  enters  the  marl  is  capped  and  pointed  with  steel 
so  that  it  will  penetrate  more  easily,  Ttfhile  the  other  end  is  provided 
with  a  handle  for  raising  the  apparatus.  The  two  vertical  edges  of  the 
barrel  are  sharpened  so  as  to  cut  the  marl.  When  the  instrument  has 
been  driven  down  to  the  desired  depth  it  is  turned  half  around,  filling 
the  half  cylinder  with  marl  for  its  entire  length,  and  then  withdrawn. 
This  gives  a  perfect  sample  of  the  bed  from  top  to  bottom. 

The  various  devices  above  described  will  generally  give  satisfactory 
results  when  operating  in  moderate  depths  of  water  and  on  any  but 
the  most  fluid  marls.  For  these  latter,  as  well  as  for  sampling  in  deep 
water,  special  devices  are  required,  which  are  described  by  Mr.  Hale 
in  the  paper  cited.  But  in  examing  deposits  of  marl  to  be  used  as 
Portland-cement  material  the  very  deep  and  very  fluid  marls  may  be 
dismissed  without  sampling.  For  under  present  economic  conditions 
such  materials  could  not  be  profitably  used  in  cement-manufacture. 

After  the  results  of  the  borings  have  been  plotted  in  such  a  way  as  to 
give  both  depth  of  water  and  thickness  of  marl,  the  amount  of  marl 
available  can  be  calculated  quite  closely.  In  making  these  estimates  it 
will  be  safest  to  assume  that  each  cubic  yard  of  marl  in  the  lake  will 
yield  900  pounds  of  dry  marl,  or  sufficient  to  make  two  barrels  of  cement. 
Each  rotary  kiln  in  the  prepared  plant  will  on  this  basis  use  about  50 
to  60  cubic  yards  of  marl  per  day,  or  about  18,000  cubic  yards  per  year. 
An  eight-kiln  plant  should  therefore  own  about  3,000,000  cubic  yards 
of  marl,  which  would  insure  a  twenty-year  supply  of  raw  material. 

List  of  references  on  marls. — Of  the  following  papers  on  marls,  those 
dealing  chiefly  with  the  origin  of  marl  deposits  are  marked  A;  those 
describing  the  deposits  of  certain  States  or  areas  are  marked  B]  and 
those  discussing  the  technology  of  marls  as  cement  materials  are 
marked  C: 

A,  B.  Blatchley,  W.  S.,  and  Ashley,  G.  H.     The  lakes  of  northern  Indiana  and 

their  associated  marl  deposits.     25th  Ann.  Rep.  Indiana  Dept.  Geology 

and  Natural  Resources,  pp.  31-321.     1901. 
A.  Davis,  C.  A.     A  contribution  to  the  natural  history  of  marl.     Journal  of 

Geology,  vol.  8,  pp.  485-497.     1900. 
A.  Davis,  C.  A.      A  remarkable  marl  lake.      Journal  of  Geology,  vol.  8,  pp. 

498-500.     1900. 


FRESH-WATER  MARLS.  347 

A.  Davis,  C.  A.     Second  contribution  to  the  natural  history  of  marl.     Journal 
of  Geology,  vol.  9,  pp.  491-506.     1901. 

A.  Davis,  C.  A.     A  contribution  to  the  natural  history  of  marl.     Vol.  8,  pt.  3, 

Reports  Michigan  Geological  Survey,  pp.  65-102.     1903. 

B,  C.     Eckel,  E.  C.     Cement  materials  and  cement  industries  of  the  United 

States.     Bulletin  243,  U.  S.  Geological  Survey,     1905. 
B.  Ells,  R.  Vv7.     Marl  deposits  of  eastern  Canada.     Ottawa  Naturalist,  vol.  16, 

pp.  59-69.     1902. 
B.  Fall,  D.     Marls  and  clays  in  Michigan.     Vol.  8,  pt.  3,  Reports  Michigan 

Geological  Survey,  pp.  343-348.     1903. 
AyB,Cf     Hale,  D.  J.     Marl  and  its  application  to  the  manufacture  of  Portland 

cement.     Vol.  8,  pt.  3,  Reports  Michigan  Geological  Survey,  pp.  1-64, 

103-190.     1903. 

A.  Lane,  A.  C.     Notes  on  the  origin  of  Michigan  bog-limes.     Vol.  8,  pt.  3, 

Reports  Michigan  Geological  Survey,  pp.  199-223.     1903. 

B,  C.  Lane,  A.  C.     List  of  marl  localities  and  Portland-cement  mills  in  Michigan. 

Vol.  8,  pt.  3,  Reports  Michigan  Geological  Survey,  pp.  224-342.     1903. 
<7.  Lathbury,  B.  B.     The  development  of  marl  and  clay  properties  for  the 
manufacture   of    Portland   cement.     Vol.    8,  pt.    3,  Reports   Michigan 
Geological  Survey,  pp.  191-198.     1903. 

B.  Ries,  H.     Lime  and  cement  industries  of  New  York.     Bulletin  44,  New 

York  State  Museum,  pp.  326.     1£01. 

A,  B.  Russell,  I.  C.     The  Portland-cement  industry  in  Michigan.     22d  Ann. 
Rep.  U.  S.  Geol.  Survey,  pt.  3,  pp.  629-685.     1902. 

C.  Spackman,  H.  S.     The  manufacture  of  cement  from  marl  and  clay.     Proc. 

Engineers'  Club  of  Phila1.,  April,  1903.    Engineering  News,  vol.  49,  pp. 
492-494.     June  4,  1903. 


CHAPTER  XXVI. 
ALKALI  WASTE:  BLAST-FURNACE  SL^G. 

THE  two  raw  materials  to  be  discussed  in  the  present  chapter  agree 
in  being  waste  products  or  by-products  of  other  industries  which,  because 
of  their  chemical  composition,  can  be  used  in  Portland-cement  manu- 
facture. In  almost  every  other  respect  they  differ.  Alkali  waste  is 
a  fine-grained,  soft  and  pure  form  of  lime  carbonate.  Slag  is  very  hard, 
coarse-grained,  and  is  composed  of  lime  (CaO),  silica,  and  alumina. 

Waste  products  or  by-products  can,  of  course,  be  usually  obtained 
at  a  low  or  nominal  cost,  and  on  this  account  both  slag  and  alkali  waste 
assume  an  importance  entirely  out  of  proportion  to  their  other  proper- 
ties. But  it  must  be  recollected  that  as  by-products  their  production 
and  quality  depend  entirely  upon  the  condition  of  the  industries  of 
which  they  are  wastes,  and  that  no  furnace  manager  or  alkali- works 
superintendent  will  run  his  plant  solely  in  or*der  to  turn  out  a  by-product 
regular  in  amount  and  composition.  For  this  reason  it  is  essential  that 
a  cement-plant  using  a  waste  product  must  be  closely  identified  in  owner- 
ship with  the  furnace  or  works  which  furnishes  this  waste  product. 
Common  ownership  is  practically  the  only  way  of  insuring  a  sufficient 
and  regular  supply  of  satisfactory  composition. 

Alkali  Waste. 

\ 

A  large  amount  of  waste  material  results  from  the  processes  used 
at  alkali  works  in  the  manufacture  of  caustic  soda.  This  waste  mate- 
rial is  largely  a  precipitated  form  of  calcium  carbonate,  and  if  sufficiently 
free  from  injurious  impurities,  furnishes  a  cheap  source  of  lime  for  use 
in  Portland-cement  manufacture.  The  value  of  the  waste  for  this  pur- 
pose depends  largely  on  the  process  from  which  it  resulted. 

Leblanc-process  waste. —  The  waste  resulting  from  the  Leblanc 
process  carries  a  very  large  percentage  of  sulphur,  mostly  in  the  form 
of  lime  sulphides,  carried  over  from  the  pyrites  used  in  the  process.  A 

348 


ALKALI  WASTE:  BLAST-FURNACE  SLAG. 


349 


fairly  typical  analysis  *  of  Leblanc-process  waste   is  given   below  and 
will  serve  to  show  the  composition  of  this  material: 

Lime  carbonate  (CaCO3) 41 .20 

Lime  sulphate  (CaSO4) 2 . 53 

Lime  hydrate  (CaH2O2) 8.72 

Lime  disulphide  (CaS2) 5 . 97 

Lime  sulphide  (CaS) 25.79 

Sodium  sulphide  (Na2S). 1 .44 

Magnesium  silicate  (MgSiO3) 3.63 

Phosphates  of  iron  and  alumina 8.91 

This  material  is  obviously  unfit  for  use  in  the  manufacture  of  Port- 
land cement.  Attempts  have  been  made  to  recover  the  sulphur  con- 
tained in  the  waste,  but  the  removal  of  this  constituent  is  never  suffi- 
ciently perfect  to  permit  the  resulting  waste  to  be  of  use  to  the  cement 
manufacturer. 

Ammonia-process  waste. — The  waste  from  ammonia-process  works 
is,  on  the  contrary,  a  very  pure  mass  of  precipitated  lime,  mostly  in  the 
carbonate  form,  though  some  lime  hydrate  is  always  present.  As  pyrite 
is  not  used  in  this  process,  the  sulphur  in  the  waste  is  commonly  well 
within  Portland-cement  limits.  The  magnesia  content  of  the  waste  may 
or  may  not  be  High,  according  to  the  character  of  the  limestone  that  has 
been  used  in  the  process  of  soda-manufacture.  When  a  pure  limestone 
low  in  magnesium  carbonate  has  been  used,  the  waste  will  be  low  in 
magnesia  and  is  then  a  very  satisfactory  Portland-cement  material.  The 
following  analyses  are  representative  of  the  waste  obtained  at  alkali- 
plants  using  the  ammonia  process. 

TABLE  158. 
ANALYSES  OF  ALKALI  WASTE,  AMMONIA  PROCESS. 


1. 

2. 

3. 

4. 

5. 

Silica  (SiO2) 

0  CO 

1.98 

1.75 

n.  d. 

0.98 

Alumina  (A12O3) 

1.41 

Iron  oxide  (Fe2O3)   

}    3-04{ 

1.38 

>    0.61 

2.20 

1.62 

Lime  (CaO) 

53  33 

48  29 

50  60 

52  40 

50  40 

Magnesia  (MgO).  

0.48 

1.51 

5.35 

3.75 

4.97 

Alkalies  (K2O  Na2O) 

0  20 

0  64 

0  64 

0  20 

0.50 

Sulphur  trioxide  (SO3)  

n.  d. 

1  26 

n.  d. 

n.  d. 

n  d 

Sulphur  (S)               

n.  d. 

n.  d. 

0.10 

n.  d. 

0  06 

Carbon  dioxide  (CO.)  

42.43 

39.60 

41.17 

n.  d. 

Water 

n  d 

3  80 

V  41.  70  < 

n   d 

n  d 

The  analyses  given  in  the  above  table  are  of  alkali  wastes  which 
have  at  one  time  or  another  been  used  in  the  manufacture  of  Portland 


*  Kingzett,  C.  T.     The  Alkali  Trade,  p.  134. 


350  CEMENTS,  LIMES,  AND  PLASTERS. 

cement  either  in  the  United  States  or  in  England.  The  effect  on  the 
waste  when  a  magnesian  limestone  is  used  in  the  alkali-plant  is  well 
shown  by  analyses  3,  4  and  5,  in  all  of  which  the  magnesia  is  high  for  a 
Portland-cement  material. 

At  the  only  American  cement-plant  which  uses  alkali  waste  the 
materials  (clay  and  waste)  are  mixed  wet.  The  waste  carries  90  to  95 
per  cent  of  lime  carbonate/  while  th£  clay  used  gives  the  following 
analysis : 

Silica  (SiO2) 63.54 

Alumina  (A12O3) \  _ 

Iron  oxide  (Fe2O3) J 

Lime  (CaO) 1 .66 

Magnesia  (MgO) 1 .05 

Alkalies  (K2O,Na2O) 0.78 

Carbon  dioxide  (CO2) 2.47 

Water 7.05 

The  clay  is  put  through  a  rotary  drier  and  ground  in  a  dry -pan, 
after  which  the  waste  and  clay  are  mixed  in  a  wet  pug-mill  and  ground 
in  wet  tube  mills.  The  mix  is  made  drier  than  at  most  of  the  plants 
using  marl  and  contains  usually  about  40  per  cent  of  water. 

It  is  not,  of  course,  necessary  that  wet  mixing  should  be  practiced 
when  alkali  waste  is  employed  as  one  raw  material.  The  waste  could 
be  dried,  though  it  is  possible  that  its  physical  properties  might  render 
this  more  difficult  than  drying  limestones  or  clays. 

List  of  references  on  alkali  waste  as  a  cement  material. — The  follow- 
ing brief  list  covers  the  few  available  references  on  this  subject: 

Butler,  D.  B.  [Alkali  waste  used  in  England.]  Portland  Cement:  its  Manu- 
facture, Testing,  and  Use,  pp.  25-27.  1899. 

Lathbury,  B.  B.  The  Michigan  Alkali  Company's  plant  for  manufacturing 
Portland  cement  from  caustic-soda  waste.  Engineering  News,  June  7, 
1900. 

Lathbury,  B.  B.,  and  Spackman,  H.  S.  The  Michigan  Alkali  Company's  plant, 
Wyandotte,  Michigan.  The  Rotary  Kiln,  pp.  110-119.  1902. 

Redgrave,  G.  R.  [Use  of  alkali  waste  in  England.]  Calcareous  Cements: 
their  Nature  and  Uses,  pp.  182-184.  1895. 

Blast-furnace  Slag. 

True  Portland  cements,  which  must  be  sharply  distinguished  from 
the  slag  (or  puzzolan)  cements  described  in  Part  VII  of  this  volume,  can 
be  made  from  mixtures  which  contain  blast-furnace  slag  as  one  ingredient. 
In  this  case  the  slag  is  intimately  mixed  with  limestone  and  the  mixture 
is  finely  powdered.  It  is  then  burned  in  kilns  and  the  resulting  clinker 
pulverized. 


ALKALI  WASTE:  BLAST-FURNACE  SLAG. 


351 


The  slags  from  iron  furnaces  consist  essentially  of  lime  (CaO),  silica 
(SiO2),  and  alumina  (A^Os),  though  small  percentages  of  iron  oxide 
(FeO),  magnesia  (MgO),  and  sulphur  (S)  are  commonly  present. 
Slag  may  therefore  be  regarded  as  a  very  impure  limestone  or  a  very 
calcareous  clay  from  which  the  carbon  dioxide  has  been  driven  off. 

Two  plants  are  at  present  engaged  in  the  United  States  in  the 
manufacture  of  true  Portland  cement  from  slag,  and  there  seems  to  be 
no  reason  why  this  cheap  and  satisfactory  raw  material  should  not 
become  an  important  factor  in  the  cement  industry  of  the  country. 

Slags  in  general. — Slags  are  the  fusible  silicates  formed,  during  the 
'  smelting  or  refining  of  metals,  by  the  combination  of  the  fluxing  materials 
with  the  gangue  of  the  ore.  The  composition  of  the  slag,  therefore,  will 
be  determined  by  the  composition  and  relative  proportions  of  the  fluxes 
and  the  gangue.  In  general,  the  slag  will  contain  only  those  elements 
which  are  present  in  either  the  gangue  or  the  flux,  though  it  may  carry 
also  a  percentage,  usually  small,  of  the  metal  which  is  being  smelted  or 
treated.  In  some  processes  also  the  composition'  of  the  slag  may  be 
slightly  modified  through  the  action  of  the  fuel,  from  which  certain 
impurities  may  be  taken  up. 

While  many  elements  may  occur  in  slags,  those  which  are  of  uni- 
versal or  even  common  occurrence  are  comparatively  few.  The  slags 
commonly  found  in  iron  metallurgy  consist  essentially  of  silica,  alu- 
mina, iron  oxide,  and  lime,  with  or  without  magnesia.  Alkalies,  sul- 
phur, and  phosphorus  are  also  almost  invariably  present,  but  in  small 
percentages. 

The  following  analyses  of  slags  from  various  furnaces  will  serve 
to  give  some  idea  of  the  range  in  composition  of  these  products. 

TABLE  159. 
ANALYSES  OF  IRON-FURNACE  SLAGS. 


Silica  (SiO2)       

30  00 

30.72 

32  51 

32  90 

26  88 

31  65 

Alumina  (A12O3)     

28  00 

16.40 

13.91 

13.25 

24.12 

17  00 

Iron  oxides  (FeO,Fe2O3)  . 
Lime  (CaO) 

0.75 
32  75 

0.43 

48  59 

0.48 
44  75 

0.46. 
47  30 

0.44 
45  11 

0.65 
47  20 

Magnesia  (MgO)       

5  25 

1  28 

2  20 

1  37 

1  09 

1  36 

Lime  sulphide  (CaS).  .  .  . 

1.90 

2.16 

4.90 

3.42 

1.86 

n.  d. 

Silica  (SiO2) 

28  35 

38  00 

31  50 

32  20 

33  10 

Alumina  (A12O3) 

18  15 

10  00 

18  56 

15  50 

12  60 

Iron  oxides  (FeO,Fe2O3) 

1  50 

n  d 

n  d 

n   d 

n  d 

Lime  (CaO)         

47  40 

46.0 

42  22 

48  14 

49  98 

Magnesia  (MgO)  

2.45 

n.  d. 

3.18 

2  27 

2.45 

Lime  sulphide  (CaS) 

n  d 

n.  d. 

n  d 

n  d 

n  d 

352  CEMENTS,  LIMES,  AND  PLASTERS. 

Slags  used  as  Portland-cement  materials. — The  slags  used  in  Port- 
land-cement manufacture  are  iron  blast-furnace  slags  of  the  more  basic 
types — i.e.,  those  in  which  the  lime  (CaO)  reaches  30  per  cent  or  over. 
The  higher  the  lime,.,  up  to  say  50  per  cent,  the  more  valuable  the  slag 
for  this  use.  The  composition  of  the  slags  will  usually  be  controlled, 
however,  by  the  requirements  of  the  furnaces,  not  by  the  needs  of  the 
cement-plant.  ^ 

The  following  shows  the  range  in  composition  of  the  slags  used  at 
a  German  Portland-cement  plant. 

ANALYSES  OF  SLAG  USED  IN  PORTLAND-CEMENT  MANUFACTURE. 

Per  Cent. 

Silica  (SiO2). 30      to  35 

Alumina  (A12O3) 10       "14 

Iron  oxide  (FeO) 0.2  "     1.2 

Lime  (CaO) 46      "49 

Magnesia  (MgO) 0.5  "    3.5 

Sulphur  trioxide  (SO3) 0.2  "    0.6 

As  a  Portland-cement  material  slag  possesses  one  great  advantage 
in  addition  to  its  cheapness.  This  advantage  is  chemical,  and  is  due 
to  the  fact  that  the  lime  contained  in  the  slag  is  present  in  the  form 
of  oxide  (CaO),  instead  of  carbonate  (CaCOs),  as  in  limestones.  It  does 
not  require  to  be  decarbonated,  and  therefore  a  mixture  made  up  of 
slag  and  clay  will  clinker  with  less  fuel  than  one  consisting  of  limestone 
and  clay. 

Opposed  to  this  chemical  advantage  is  a  physical  disadvantage. 
If  the  slag  is  allowed  to  cool  as  it  issues  from  the  furnaces,  it  solidifies 
into  very  hard  and  tough  masses  much  more  resistant  than  the  hard- 
est of  limestones.  In  order  to  avoid  this  difficulty,  it  is  the  common 
practice  to  "granulate"  the  slag,  i.e.  to  run  it  direct  from  the  furnace 
into  cold  water.  This  proceeding  breaks  up  the  slag  into  little  porous 
granules  -^  to  J  inch  in  diameter,  and  incidentally  removes  part  of 
the  sulphur  contained  in  the  slag.  But  to  offset  these  gains,  it  intro- 
duces a  large  amount  of  water  into  the  product,  so  that  a  granulated 
slag  may  carry  from  20  to  40  per  cent  of  water,  and  this  greatly  increases 
the  cost  of  drying. 

As  the  chemical  and  physical  properties  of  slag  introduce  certain 
interesting  features  into  the  manufacture  of  Portland  cement  from  a 
limestone-slag  mixture,  this  mixture  will  be  discussed  separately  on 
later  pages. 


CHAPTER  XXVII. 
CLAYS,  SHALES,  AND  SLATES. 

EXCEPT  when  a  very  clayey  limestone  or  a  slag  is  one  component  of 
a  Portland-cement  mixture,  the  silica,  alumina  and  iron  oxide  necessary 
for  the  mix  are  always  supplied  in  the  form  of  clay,  shale,  or  slate. 

The  materials  known  respectively  as  clays,  shales,  and  slates  are 
of  practically  the  same  composition  and  ultimate  origin,  but  differ  in 
their  degree  of  consolidation. 

Clays  are  ultimately  derived  from  the  decay  of  older  rocks,  the 
finer  particles  resulting  from  this  decay  being  carried  off  and  deposited 
by  streams  along  their  channels,  in  lakes,  or  along  parts  of  the  seacoast 
or  sea-bottom  as  beds  of  clay.  In  chemical  composition  the  clays  are 
composed  essentially  of  silica  and  alumina,  though  iron  oxide  is  almost 
invariably  present  in  more  or  less  amount,  while  lime,  magnesia,  alka- 
lies, and  sulphur  are  of  frequent  occurrence,  though  usually  only  in 
small  percentages. 

Shales  are  clays  which  have  become  hardened  by  pressure.  The 
so-called  "fire-clays"  of  the  Coal  Measures  are  shales,  as  are  many 
of  the  other  "clays"  of  commerce.  The  slates  include  those  clayey 
rocks  which  through  pressure  have  gained  the  property  of  splitting 
readily  into  thin  parallel  leaves. 

Clays. — The  term  clay  is  applied  to  fine-grained  unconsolidated 
materials  which  possess  the  property  of  plasticity  when  wet,  while  they 
lose  this  property  and  harden  on  being  strongly  heated.  Being,  as 
explained  below,  the  finer  de*bris  resulting  from  the  decay  of  many 
different  kinds  of  rocks,  the  clays  will  naturally  differ  greatly  among 
themselves  in  composition,  etc. 

Origin  of  clays. — When  rocks  of  any  kind  are  exposed  to  atmospheric 
action,  more  or  less  rapid  disintegration  sets  in.  This  is  due  partly  to 
chemical  and  partly  to  physical  causes.  It  is  hastened,  for  example, 
by  the  dissolving  out  of  any  soluble  minerals  that  may  occur  in  the 
rock,  by  the  expansion  and  contraction  due  to  freezing,  and  by  the 
action  of  the  organic  acids  set  free  by  decaying  vegetable  matter.  The 

353 


354  CEMENTS,  LIMES,  AND  PLASTERS. 

more  soluble  ingredients  of  the  rock  are  usually  removed  in  solution 
by  surface  or  percolating  waters,  while  the  more  insoluble  portions 
are  either  left  behind  or  are  carried  off  mechanically  by  streams.  These 
relatively  insoluble  materials  when  sufficiently  fine  grained  constitute 
the  clays.  When  they  are  left  as  a  deposit  in  the  spot  where  the  orig- 
inal rock  disintegrated,  they  are  cajled  residual  clays;  when  they  are 
carried  off  by  surface-waters  and  finally  deposited  in  the  sea  or  along 
river-beds  they  are  transported  or  sedimentary  clays.  A  third  class  of 
particular  interest  to  the  cement  manufacturer  are  the  glacial  clays, 
deposited  under  or  in  front  of  the  glaciers  which  formerly  covered  most 
of  the  northern  states. 

Composition  of  clays. — The  residual,  sedimentary  and  glacial  clays 
usually  differ  markedly  in  composition,  owing  to  the  different  manner 
in  which  they  have  been  deposited.  The  residual  clays,  for  example, 
are  apt  to  contain  coarse  fragments  of  any  very  insoluble  and  hard 
material  which  the  original  rock  may  have  contained.  A  residual 
clay  arising  from  the  decay  of  a  granite  will  probably  contain  frag- 
ments of  quartz;  one  derived  from  a  limestone  may  contain  chert  or 
flint,  as  well  as  masses  of  undissolved  lime  carbonate.  A  sedimen- 
tary clay,  on  the  other  hand,  having  been  transported  by  water  for 
great  distances,  has  usually  lost  all  its  coarser  material,  and  is  a  fine 
grained  and  homogeneous  product.  The  glacial  clays,  being  formed 
mechanically  by  the  abrading  power  of  the  ice,  show  even  less  homo- 
geneity than  the  residual  clays,  and  are  apt  to  contain  much  sand, 
gravel,  and  pebbles. 

Clays  used  in  Portland-cement  manufacture. — For  use  as  Portland- 
cement  materials  clays  should  be  as  free  as  possible  from  gravel  and 
sand,  as  the  silica  present  as  pebbles  or  grit  is  practically  inert  in  the 
kiln  unless  ground  more  finely  than  is  economically  practicable.  In 
composition  they  should  not  carry  less  than  55  per  cent  of  silica,  and  pref- 
erably from  60  to  70  per  cent.  The  alumina  and  iron  oxide  together 
should  not  amount  to  more  than  one-half  the  percentage  of  silica,  and 
the  composition  will  usually  be  better  the  nearer  the  ratio  Al203+Fe2O3 

Si02  . 

=  — - —  is  approached. 
o 

Nodules  of  lime  carbonate,  gypsum,  or  pyrite,  if  present  in  any  quan- 
tity, are  undesirable;  though  the  lime  carbonate  is  not  absolutely 
injurious.  Magnesia  and  alkalies  should  be  low,  preferably  not  above 
3  per  cent. 

The  clays  actually  used  in  cement  plants  may  be  separated,  for  con- 
venience, into  the  normal  clays  and  the  limey  clays.  In  this  section  the 


CLAYS,  SHALES,  AND    SLATES. 


355 


dividing  line  between  these  classes  will  be  fixed  arbitrarily  at  5  per 
cent  of  lime  (CaO)  and  magnesia  (MgO)  together,  all  clays  containing 
over  5  per  cent  of  both  oxides  being  called  limey  clays,  while  those 
carrying  less  than  5  per  cent  are  termed  normal  clays. 


TABLE   160. 
ANALYSES  OF  NORMAL  CLAYS  USED  IN  AMERICAN  CEMENT-PLANTS. 


Silica  (Si02). 

Alumina 
(A1203). 

If 

1 

1 

1 

1 

1 

Sulnhur 
Trioxide 

(S03). 

|i 

Water. 

1 

1 

53.30 

23.29 

9.52 

0.35 

1.49 

n.  d. 

n.  d. 

n.  d. 

n.  d. 

1.62 

2 

65.12 

19.05 

7.66 

0.34 

0.31 

n.  d. 

n.  d. 

n.  d. 

n.  d. 

2.44 

3 

63.73 

22.12 

9.01 

2.83 

0.21 

n,  d. 

n.  d. 

n.  d. 

2.04 

4 

53.21 

15.91 

7.25 

1.89 

6^99 

2.21 

0.97 

17.21 

2.29 

5 

59.10 

25.41 

3.61 

0.87 

1.10 

0.31 

9.81 

2.32 

6 

58.02 

26.12 

3.70 

1.00 

1.55 

0.33 

9.27 

2.22 

7 

57.25 

26.15 

3.09 

1.10 

1.88 

0.39 

9.30 

2.19 

8 

58.25 

18.56 

7.35 

3.10 

1.28 

2.35 

0.45 

8.55 

2.25 

9 

74.29 

12.00 

4.92 

0.41 

0.68 

2.56 

n.  d. 

n.  d. 

n.  d. 

4.39 

10 

63.54 

24.00 

.66 

1.05 

0.78 

2.47 

7.05 

2.65 

11 

64.65 

24.31 

.16 

1.92 

n.  d. 

n.'  d. 

n.  d. 

n.  d. 

2.66 

12 

60.28 

27.10 

.20 

n.  d. 

n.  d. 

n.  d. 

8.38 

2.22 

13 

60.30 

29.78 

.98 

n.  d. 

n.  d. 

n.  d. 

8.30 

2.03 

14 

61.40 

25.08 

.40 

n.  d. 

n.  d. 

n.  d. 

6.60 

2.45 

15 

63.82 

25.36 

3.42 

n.  d. 

n.  d. 

n.  d. 

6.96 

2.52 

16 

63.07 

24.00 

3.  CO 

1.20 

n.  d. 

n.  d. 

8.80 

2.63 

17 

61.92 

16.58 

7.84 

2.01 

1.58 

3.64 

tr. 

n.  d. 

n.  d. 

2.53 

18 

65.68 

24.08 

2.C1 

1.75 

n.  d. 

n.  d. 

n.  d. 

n.  d. 

2.73 

19 

62.5 

20.2 

7.5 

0.8 

1.8 

n.  d. 

0.4 

n.  d. 

n.  d. 

2.26 

20 

58.90 

27.50 

4.08 

0.79 

n.  d. 

n.  d. 

n.  d. 

n  d. 

2.14 

21 

59.10 

24.01 

2.20 

2.00 

n.  d. 

n.  d. 

n.  d. 

n.  d. 

2.46 

22 

64.85 

17.98 

5.92 

2.24 

1.40 

n.  d. 

n.  d. 

4.98 

2.82 

23 

58.04 

14.63 

9.27 

1.53 

2.02 

n.  d. 

0.37 

12 

.67 

2.33 

1,2.  Whitecliffs  P.  C.  Co.,  Whitecliffs,  Ark.     Trans.  Amer.  Irjst.  Mining  Engrs.,  vol.  21. 

3.  Santa  Cruz,  Calif.     Mineral  Industry,  vol.  1,  p.  52. 

4.  Pacific  P.  C.  Co.,  Suisun,  Calif.     C.  J.  Wheeler,  analyst, 
5. 

I 


10. 
11. 
12. 
13. 
14. 
15. 
16. 
17. 
18. 
19. 
20 
21. 
22. 
23. 


Bedford  P.  C.  Co.,  Bedford,  Ind.     A.  W.  Smith,  analyst.     25th  Ann.  Rep.  Indiana  Dept. 

Geology,  p.  328. 

Wyandotte  P.  C.  Co.,  Wyandotte,  Mich. 
Peerless  P.  C.  Co.,  Union  City,  Mich.     Lundteigen,  analyst. 
Peninsular  P.  C.  Co.,  Cement  City,  Mich. 


Catskill  P.  C.  Co.,  Smiths  Landing,  N.  Y. 

American  Cement  Co.,  Jordan,  N.  Y 

Iroquois  P.  C.  Co.,  Caledonia,  N.  Y.' 

Hudson  P.  C.  Co.,  Hudson  N.  Y.     Heiberg  and  Roney,  analysts. 

Castalia  P.  C.  Co.,  Castalia,  Ohio. 

Omega  P.  C.  Co.,  Jonesville.  Mich.     Vol.  8,  Mich.  Geol.  Survey,  p.  229. 

Almendares  P.  C.  Co.,  Marinao,  Cuba.     Engineering  Record,  vol.  49,  p.  37. 


356 


CEMENTS,  LIMES,  AND   PLASTERS. 


TABLE  161. 
ANALYSES  OF  LIMEY  CLAYS  USED  IN  AMERICAN  CEMENT-PLANTS. 


Silica  (SiO2). 

Alumina 
(A12O3). 

1. 

HH 

I 

I 

'     3 

<SX 
|3 

f 

I 

i 

< 

• 

"O 

11? 

ja£cc 
~r*-s 

OQ 

V 

3U 

J*      CM 
oO 

as°~ 

1 

1 

9  5 
•  | 

< 

1 

47.5 

4.0 

2.0 

1.5 

n.  d. 

13 

.5 

1.44 

33.0 

2 

61.70 

18.00 

8.40 

2.91 

n.  d. 

n.  d. 

13.30 

3.43 

3 

57.74 

17.76 

7.80 

3.52 

n.  d. 

n.  dV 

12.30 

3.25 

4 

56.74 

19.43 

4.83 

7.27 

3.05 

n.  d. 

n.  d. 

10.39 

2.34 

5 

55.27 

10.20 

3.40 

9.12 

5.73 

n.  d. 

n.  d. 

n.  d. 

n.  d. 

4.06 

6 

40.56 

8.52 

2.84 

20.94 

1.32 

1.97 

n.  d. 

17.90 

5.95 

3.57 

7 

59.36 

10.01 

23.80 

2.40 

0.58 

1.71 

2.05 

5.93 

8 

58.05 

25.50 

2.50 

3.24 

n.  d. 

n.  d. 

"8.80 

2.27 

9 

46.40 

16.30 

14.20 

2.06 

0.75 

n.  d. 

23.40 

7.00 

2.85 

10 

46.81 

14.21 

14.04 

3.61 

3.04 

1.18 

15.75 

n.  d. 

3.29 

11 

55.84 

8.90 

3.02 

9.98 

5.16 

n.  d. 

n.  d. 

13.68 

4.69 

12 

55.27 

28.15 

5.84 

2.25 

n.  d. 

0.12 

n.  d. 

n.  d. 

1.96 

13 

45.21 

19.08 

6.74 

11.17 

1.57 

n.  d. 

1.55* 

10.47 

4.17 

1.75 

14 

50.08 

14.50 

4.61 

6.62 

4.40 

5.10 

n.  d. 

n.  d. 

n.  d. 

2.62 

15 

40.48 

20.95 

14.45 

0.47 

3.14 

n.  d. 

11.87 

8.50 

1.93 

16 

42.85 

13.51 

4.49 

12.69 

3.32 

3.08 

2.85 

13.57 

n.  d. 

2.38 

17 

53.50 

24.20 

5.15 

2.15 

n.  d. 

n.  d. 

14.10 

2.21 

18 

52.00 

31.00 

7.10 

3.33 

n.  d. 

n.  d. 

n.  d. 

n.  d. 

1.68 

19 

52.10 

35.56 

5.90 

3.33 

n.  d. 

n.  d. 

n.  d. 

n.  d. 

1.46 

20 

51.56 

14.50 

3.84 

9.80 

n.  d. 

n.  d. 

tr. 

7.70 

n.  d. 

2.81 

21 

47.45 

19.85 

17.80 

0.09 

4.34 

1.03 

n.  d. 

n.  d. 

2.39 

22 

60.16 

28.58 

1.97 

6.56 

n.  d. 

n.  d. 

n.  d. 

n.  d. 

2.10 

23 

59.18 

27.74 

1.89 

8.65 

n.  d. 

n.  d. 

n.  d. 

n.  d. 

2.13 

24 

54.96 

23.09 

5.03 

14.57 

1.37 

0.48 

0.57 

n.  d. 

n.  d. 

1.95 

25 

41.69 

14.86 

6.71 

12.80 

4.96 

2.24 

n.  d. 

16.74 

1.93 

26 

39.23 

12.13 

2.79 

21.61 

2.69 

1.69 

n.  d. 

19.84 

2.63 

27 

53.32 

24.22 

7.17 

2.05 

n.  d. 

n.  d. 

7.85 

n.  d. 

2.20 

CaS04. 


1. 
2. 
3. 

5*. 
6. 
7. 
8. 
9. 
10. 

11. 
12. 
13. 
14. 
15. 
16. 
17. 
18. 
19. 
20. 
21. 
22. 
23. 
24. 
25. 
26. 
27. 


California  P.  C.  Co.,  Colton,  Cal. 
Wabash  P.  C.  Co.,  Stroh,  Ind. 


Sandusky  P.  C.  Co.,  Syracuse,  Ind.     25th  Ann.  Rep.  Indiana  Dept.  Geology,  p.  28. 
Monolith  P.  C.  Co.,  Bristol,  Ind.     21st  Ann.  Rep.  U.  S.  Geol.  Survey,  pt.  6,  p.  400. 
Millens  P.  C.  Works,  South  Bend,  Ind.     25th  Ann.  Rep.  Indiana  Dept.  Geology,  p.  25. 
Peninsular  P.  C.  Co.,  Cement  City,  Mich. 
Wyandotte  P.  C.  Co.,  Wyandotte,  Mich.     22d  Ann.  Rep.  U.  S.  Geol.  Survey. 

Lathbury  and   Spackman,   analysts.     Engineering 
News,  vol.  43,  p.  373. 

Newaygo,  P.  C.  Co.,  Newaygo,  Mich.     Prospectus. 

Glens  Falls  P.  C.  Co.,  Glens  Falls,  N.  Y.    .Mineral  Industry,  vol.  6,  p.  97. 
Millen  P.  C.  Co.,  Wayland,  N.  Y. 

Montezuma  P.  C.  Co.,  Montezuma,  N.  Y.     Mineral  Industry,  vol.  1,  p.  52. 
Empire  P.  C,  Co.,  Warners,  N.  Y.     Cummings,  "American  Cements",  p.  253. 

Genesee  P.  C.  Co.,  Wayland,  N.  Y. 

Hudson  P.  C.  Co.,  Hudson,  N.  Y.     Heiberg  and  Roney,  analysts. 

Castalia  P.  C.  Co.,  Castalia,  Ohio. 

Buckeye,  P.  C.  Co.,  Harper,  Ohip.     Mineral  Industry,  vol.  1,  p.  52. 

Clay  used  for  reduce^ at  &  plant ^n  the  Lehigh  district,  Pa. 

Orangeville,  Ontario,  Canada.     Report  Ontario  Bureau  of  Mines,  1901. 
Imperial  P.  C.  Co.,  Owen  Sound,  Ontario,  Canada. 

Canadian  P.  C.  Co.,  Marlbrook,  Ontario,  Canada. 


CLAYS,  SHALES,  AND  SLATES. 


357 


Shales. 

It  has  been  noted  above  that  shales  are  simply  clays  which  have 
been  hardened  by  pressure.  This  statement,  while  approximately 
correct,  requires  some  restriction.  For  the  shales  were  formed  almost 
entirely  from  extensive  deposits  of  clays  of  marine  origin,  and,  there- 
fore, do  not  show  the  same  irregularities  of  composition,  etc.,  that  modern 
clays  exhibit.  .  Shales,  for  example,  rarely  are  so  full  of  coarse  sand 
and  gravel  as  the  glacial  clays  of  Michigan  and  other  Northern  States. 


TABLE  162. 

ANALYSES  OF  NORMAL  SHALES  USED  IN  AMERICAN  CEMENT-PLANTS. 


Silica  (SiO2). 

Alumina 

(A1203). 

0>     . 

S3 

| 

h-  1 

1 

3 

•is 

0>  M 

J5 

Alkalies 
(K20,Na20). 

Sulphur  Tri- 
oxide  (S03). 

*s 

II 

r 

1 

SiO2 
Al203+Fe203 

1 

57.98 

18.26 

4.57 

1.75 

1.83 

n.  d. 

1.28 

12.08 

2 

65.99 

21.57      6.07 

0.47 

0.82 

n.  d. 

n.  d. 

n.  d. 

n.d. 

3 

63.30 

26.00 

1.25 

1.25 

n.  d. 

n.  d. 

n.  d. 

6.25 

4 

63.56 

27.32 

1.20 

1.20 

n.  d. 

n.  d. 

n.  d. 

n.  d. 

5 

55.80 

30.20 

1.16 

n.  d. 

n.  d. 

n.  d. 

n.  d. 

n.  d. 

6 

56.30 

29.86 

n.  d. 

n.  d. 

n.  d. 

n.  d. 

n.  d. 

n.  d. 

7 

60.00 

23.26 

4.32 

0.90 

1.12 

n.  d. 

n.  d. 

6.16 

8 

62.67 

19.99 

5.46 

1.25 

0.72 

n.  d. 

n.  d. 

n.  d. 

n.  d. 

9 

60.15 

19.78 

9.10 

0.52 

0.10 

n.  d. 

tr. 

n.  d. 

n.  d. 

10 

60.97 

20.66 

6.59 

0.65 

1.13 

n.  d. 

tr. 

n.  d. 

n.  d. 

11 

55.00 

21.79 

9.26 

n.  d. 

n.  d. 

n.  d. 

n.  d. 

8.61 

12 

54.70 

31.68 

1.15 

n.  d. 

n.  d. 

n.  d. 

n.  d. 

n.  d. 

1.72 

13 

64.30 

33.60 

1.46 

1.30 

n.  d. 

n.  d. 

n.  d. 

n.  d. 

1.91 

14 

70.20 

26.90 

n.  d. 

n.  d. 

n.  d. 

n.  d. 

n.  d. 

n.  d. 

2.61 

15 

61.09 

19.19 

6.78 

2.51 

0.65 

3.16 

1.42 

5.13 

16 

61.15 

18.47 

5.05 

0.98 

2.26 

n.  d. 

0.91  ' 

7.02 

1? 

58.24 

18.56 

7.68 

0.61 

0.24 

n.  d. 

n.  d. 

10.04 

18 

59.64 

19.14 

7.59 

0.26 

2.31 

4.33 

n.  d. 

4.71 

19 

62.10 

20.09 

7.81 

0.65 

0.96 

n.  d. 

0.49 

20 

59.02 

29.84 

0.68 

2.16 

n.  d. 

n.  d. 

n.  d. 

n.  d. 

21 

58.44 

27.45 

1.16 

2.23 

n.  d. 

n.  d. 

n.  d. 

n.d. 

22 

58.90 

27.25 

1.23 

2.18 

n.  d. 

n.  d. 

n.  d. 

n.d. 

23 

58.92 

27.00 

1.41 

2.32 

n.  d. 

n.  d. 

n.  d. 

n.d. 

24 

60.24 

30.04 

2.21 

1.55 

n.  d. 

n.  d. 

n.  d. 

n.  d. 

2.01 

25 

60.02 

26.60 

2.31 

1.62 

n.  d. 

n.  d. 

n.  d. 

n.  d. 

1.  Western  P.  C.  Co.,  Yankton,  S.  D.     Mineral  Industry,  vol.  6,  p.  97. 

2.  Crescent  P.  C.  Co.,  Wampum,  Pa. 

3.  Wellston  P.  C.  Co.,  Wellston,  Ohio.     W.  S.  Trueblood,  analyst. 
4-7.  Ironton  P.  C.  Co.,  Ironton,  Ohio.     C.  D.  Quick,  analyst. 

8-11.  Diamond  P.  C.  Co.,  Middle  Branch,  Ohio.     E.  Davidson,  analyst. 

12-14.  Hudson  P.  C.  Co.,  Hudson,  N.  Y.     Heiberg  and  Roney,  analysts. 

15.  Alpena  P.  C.  Co.,  Alpena,  Mich.     Vol.  8,  pt.  3,  Reports  Mich.  Geol.  Survey,  p.  227. 

16.  Wolverine  P.  C.  Co.,  Cold  water,  Mich. 

17.  Michigan  P.  C.  Co.,  Coldwater,  Mich.     Cement  Industry,  p.  78. 

18.  Lehigh  P.  C.  Co.,  Mitchell,  Ind.     26th  Ann.  Rep.  Indiana  Dept.  Geology,  p.  276. 

19.  Bronson  P.  C.  Co.,  Bronson,  Mich.     Mineral  Industry,  vol.  6,  p.  99. 

20.  Peerless  P.  C.  Co.,  Union  City,  Mich.     Lundteigen,  analyst. 
22-25.  Cayuga  P.  C.  Co.,  Portland  Point,  N.  Y.     J.  H.  McGuire,  analyst. 


358 


CEMENTS,  LIMES,  AND  PLASTERS. 


FIG.  69. — Pit  in  heavy  shale-bed. 


FIG.   70. — Shale-pit  worked  on  two  levels. 


CLAYS,  SHALES,  AND  SLATES. 


359 


The  limey  shales  are  almost  exclusively  shales  which  occur  inter- 
bedded,  in  comparatively  thin  layers,  with  limestones.  Occasionally 
a  limey  shale  will  owe  its  content  of  lime  almost  entirely  to  the  fossil 
shells  it  contains,  the  remainder  of  the  shale  being  practically  free  from 
carbonates.  For  both  of  the  above  reasons  limey  shales  are  apt  to- 
be  a  source  of  trouble  in  the  practical  working  of  a  plant  and  require 
considerable  care  in  quarry  management  to  insure  that  the  raw  mate- 
rials are  anywhere  near  uniform  in  composition  from  day  to  day. 

Fig.   70  shows  a  shale  deposit  which  consists   of  three  horizontal 

TABLE  163. 
ANALYSES  OF  LIMEY  SHALES  USED  IN  AMERICAN  CEMENT-PLANTS. 


3 

«  . 

? 

1 

jo 

o 

il 

13 

C  £ 

0 

II 

|1| 

o  o  O 

| 

It 

i 

3 

h-  1 

3 

a 

1HS 

0 

£ 

3 

1 

53.12 

20.60 

4.09 

4.02 

2.24 

n.  d. 

2.15 

13.70 

2 

54.30 

19.33 

5.57 

3.29 

2.57 

2.36 

n.  d. 

n.  d. 

3 

52.74 

21.73 

12.37 

2.01 

n.  d. 

11.27 

n.  d. 

4 

54.4 

18.2 

5.7 

7.2 

1.8 

n.  d. 

12.3 

5 

54.18 

19.17 

6.11 

7.05 

1.89 

n.  d. 

11.95 

6 

56.0 

22.1 

8.0 

1.5 

tr. 

10.7 

2.53 

7 

57.45 

20.56 

2.78 

4.27 

3.17 

0.35 

8.15 

8 

55.96 

22.44 

2.80 

3.78 

3.22 

0.74 

8.03 

9 

58.22 

17.68 

4.48 

3.82 

2.85 

0.43 

7.83 

10 

57.50 

21.70 

12.19 

1.93 

n.  d. 

n.  d. 

n.  d. 

11 

57.82 

21.76 

8.32 

1.81 

n.  d. 

n.  d. 

n.  d. 

12 

38.84 

17.76 

21.58 

1.78 

n.  d. 

n.  d. 

n.  d. 

13 

50.48 

8.89 

23.74 

2.21 

n.  d. 

n.  d. 

n.  d. 

5.68 

14 

46.54 

21.50 

11.51 

1.88 

n.  d. 

n.  d. 

n.  d. 

15 

46.72 

22.00 

11.82 

2.11 

n.  d. 

n.  d. 

n.  d. 

16 

56.50 

24.50 

5.14 

1.78 

n.  d. 

n.  d. 

n.  d. 

2.31 

17 

58.10 

26.14 

3.34 

2.01 

n.  d. 

n.  d. 

n.  d. 

18 

58.25 

24.18 

3.46 

2.10 

n.  d. 

n.  d. 

n.  d. 

19 

61.94 

11.58 

3.49 

5.92 

4.85 

.18 

n/d. 

n.  d. 

20 

56.64 

12.18 

3.59 

8.17 

4.29 

.31 

n.  d. 

n.  d. 

21 

61.10 

13.91 

3.62 

6.32 

3.91 

.31 

n.  d. 

n.  d. 

22 

59.36 

12.38 

3.62 

5.63 

4.62 

.30 

n.  d. 

n.  d. 

23 

53.63 

24.47 

5.94 

1.79 

n.  d. 

10.03 

2.19 

1.  Chicago  P.  C.  Co.,  Oglesby,  111.     Manufacturer's  circular. 

2.  Marquette  Cement  Co.,  Oglesby,  111.     25th  Ann.  Rep.  U.  S.  Geol.  Survey,  pt.  6,  p.  544. 

3.  German-American  P.  C.  Works,  La  Salle,  111.     W.  E.  Trussing,  analyst. 

4.  lola  P.  C.  Co.,  lola,  Kansas. 

5.  " 

6.  Kansas  P.  C.  Co.,  lola,  Kansas. 

7.  Alpena  P.  C.  Co.,  Alpena,  Mich. 

8.  " 
9. 

10-18.  Cayuga  P.  C.  Co.,  Portland  Point,  N.  Y.     J.  H.  McGuire,  analyst. 

19-22.  Bronson  P.  C.  Co.,  Bronson,  Mich.      W.  H.  Simmons,  analyst.      Vol.  8,  Mich.  Geol.  Survey, 

p.  239. 
23.  Virginia  P.  C.  Co.,  Craigsville,  Va.     "Cement  Industry",  p.  235. 


360 


CEMENTS,  LIMES,  AND   PLASTERS. 


beds  quite  different  in  composition.  They  are  consequently  worked 
as  separate  benches  or  levels,  temporary  tracks  being  run  in  on  the 
upper  levels,  while  the  main  switch  tracks  are  on  the  lowest  level. 

Examination  of  clay  deposits. — Most  of  the  notes  in  relation  to 
examining  limestone  deposits  presented  on  an  earlier  page  will  apply  to 
the  report  on  a  deposit  of  clay,  or  shale^  In  sampling,  however,  the  earth- 
auger  can  be  used  much  more  extensively,  as  the  clayey  materials  are 
usually  soft  enough  to  be  bored  readily  by  such  means.  For  valuable 
notes  on  the  use  of  the  auger,  reference  should  be  made  to  the  papers 
cited  below.* 

List  of  references  on  clays  and  shales. — The  literature  of  clays  is 
so  extensive  that  the  descriptive  papers  in  the  following  list  have  been 
arranged  by  States  in  alphabetical  order. 

GENERAL  UNITED  STATES.    Ries,  H.     The  clays  of  the  United  States  east  of 

the    Mississippi     River.     Professional    Paper 
No.  11,  U.  S.  Geological  Survey,  289  pp.    1903. 

ALABAMA.  Ries,  H.,  and  Smith,  E.     Preliminary  report  on  the  clays 

of  Alabama.     Bulletin  6,  Alabama  Geological  Survey, 
220  pp.     1900. 

ARKANSAS.  Branner,   J.    C.      The    cement    materials    of    southwest 

Arkansas.     Trans   Am.    Inst.    Min.    Engrs.,    vol.    27, 
pp.  42-63. 
Branner,  J.  C.     The  clays  of  Arkansas.     Bulletin  No.  — , 

U.  S.  Geological  Survey.     (In  press.) 
CALIFORNIA,  Johnson,  W.  D.     Clays  of  California.     9th  Ann.  Report 

California  State  Mineralogist,  pp.  287-308.     1890. 
Ries,  H.     The  clay-working  industry  of  the  Pacific  Coast 
States.     Mines   and   Minerals,   vol.   20,   pp.   487-488. 
1900. 
COLORADO.  Lakes,   A.     Gypsum  and  clay  in  Colorado.     Mines  and 

Minerals,  vol.  20.     December,  1899. 
Ries,  H.     The  clays  and  clay-working  industry  of  Colo- 
rado.    Trans.  Am.  Inst.  Min.  Engrs.,  vol.  27,  pp.  336- 
340.     1898. 
FLORIDA.  Memminger,   C.  J.     Florida  kaolin  deposits.     Eng.   and 

Min.  Journal,  vol.  57,  436  pp.     1894. 
Vaughan,  T.  W.     Fullers'  earth  deposits  of  Florida  and 
Georgia.     Bulletin  213,  U.  S.  Geological  Survey,  pp. 
392-399.     1903. 

*  Bleininger,  A.  V.  The  manufacture  of  hydraulic  cements.  Bulletin  4,  Ohio 
Geol.  Survey,  pp.  102-108.  1904.  Catlett,  C.  The  hand-auger  and  hand-drill  in 
prospecting  work.  Trans.  Amer.  Inst.  Min.  Engrs.,  vol.  27,  pp.  123-129.  1898. 
Jones,  C.  C.  A  geologic  and  economic  survey  of  the  clay  deposits  of  the  lower 
Hudson  River  Valley.  Trans.  Amer.  Inst.  Min.  Engrs.,  vol.  29,  pp.  40-83.  1900. 


CLAYS,  SHALES,  AND  SLATES. 


361 


GEORGIA. 


INDIANA. 


IOWA. 

KANSAS. 

KENTUCKY. 

LOUISIANA. 

MARYLAND. 
MASSACHUSETTS. 

MICHIGAN. 

MINNESOTA. 

MISSISSIPPI. 

MISSOURI. 
NEBRASKA. 

NEW  JERSEY. 


Ladd,  G.  E.  Preliminary  report  on  a  part  of  the  clays 
of  Georgia.  Bulletin  6A,  Georgia  Geological  Sur- 
vey, 204  pp.  1898. 

Vaughan,  T.  W.  Fullers'  earth  deposits  of  Florida  and 
Georgia.  Bulletin  213,  U.  S.  Geological  Survey,  pp. 
392-399.  1903. 

Blatchley,  W.  S.  A  preliminary  report  on  the  clays  and 
clay  industries  of  the  coal-bearing  counties  of  Indiana. 
20th  Ann.  Rep.  Indiana  Dept.  Geology  and  Natural 
Resources,  pp.  24-187.  1896. 

Blatchley,  W.  S.  Clays  and  clay  industries  of  north- 
western Indiana.  22d  Ann.  Rep.  Indiana  Dept. 
Geology  and  Natural  Resources,  pp.  105-153.  1898. 

Beyer,  S.  W.,  and  others.  Clays  and  clay  industries  of 
Iowa.  Vol.  14,  Reports  Iowa  Geol.  Survey,  pp.  27- 
643.  1904. 

Prosser,  C.  S.  Clay  deposits  of  Kansas.  Mineral  Re- 
sources U.  S.  for  1892,  pp.  731-733.  1894. 

Crump,  H.  M.  The  clays  and  building  stones  of  Kentucky. 
Eng.  and  Min.  Jour.,  vol.  66,  pp.  190-191.  1898. 

Clendennin,  W.  W.  Clays  of  Louisiana.  Eng.  and  Min. 
Jour.,  vol.  66,  pp.  456-457.  1898. 

Ries,  H.  Report  on  Louisiana  clay  samples.  Report 
Louisiana  Geological  Survey  for  1899,  pp.  263-275. 
1900. 

Ries,  H.  Report  on  the  clays  of  Maryland.  Vol.  4,  pt.  3. 
Reports  Maryland  Geological  Survey,  pp.  203-507, 
1902. 

Whittle  C.  L.  The  clays  and  clay  industries  of  Massa- 
chusetts. Eng.  and  Min.  Jour.,  vol.  66,  pp.  245-246, 
1898. 

Ries,  H.  Clays  and  shales  of  Michigan.  Vol.  8,  pt.  1. 
Reports  Michigan  Geological  Survey,  67  pp.  1900. 

Berkey,  C.  P.  Origin  and  distribution  of  Minnesota  clays. 
Amer.  Geologist,  vol.  29,  pp.  171-177.  1902. 

Eckel,  E.  C.  Stoneware  and  brick  clays  of  western  Ten- 
nessee and  northwestern  Mississippi.  Bulletin  213, 
U.  S.  Geological  Survey,  pp.  382-391.  1903. 

Wheeler,  H.  A.  Clay  deposits  of  Missouri.  Vol.  2, 
Reports  Missouri  Geological  Survey,  622  pp.  1896. 

Gould,  C.  N.,  and  Fisher,  C.  A.  The  Dakota  and  Car- 
boniferous clays  of  Nebraska.  Ann.  Rep.  for  1900, 
Nebraska  Board  of  Agriculture,  pp.  185-194.  1901. 

Cook,  G.  H.,  and  Smock,  J.  C.  Report  on  the  clay  deposits 
of  New  Jersey.  New  Jersey  Geological  Survey,  381  pp. 
1878. 


362 


CEMENTS,  LIMES,  AND   PLASTERS. 


NEW  JERSEY. 
NEW  YORK. 

NORTH  CAROLINA. 


NORTH  DAKOTA. 
OHIO. 


OREGON. 


PENNSYLVANIA. 


SOUTH  CAROLINA. 

SOUTH  DAKOTA. 

TENNESSEE. 


Ries,  H.,  Ktimmel,  B.,  and  Knapp,  G.  N.  The  clays  and 
clay  industries  of  New  Jersey.  Vol.  6,  Final  Reports 
State  Geologist,  New  Jersey.  8vo.,  548  pp.  1904. 

Jones,  C.  C.  A  geologic  and  economic  survey  of  the  clay 
deposits  of  the  lower  Hudson  River  Valley.  Trans. 
Am.  Inst.  Min.  Engrs.,vol.  29,  pp.  40-83.  1900. 

Ries,  H.  "  Clays  of  Mew  York.  Bulletin  35,  New  York 
State  Museum,  455  pp.  1900. 

Holmes,  J.  A.  Notes  on  the  kaolin  and  clay  deposits  of 
North  Carolina.  Trans.  Am.  Insf,.  Min.  Engrs.,  vol.  25, 
pp.  929-936.  1896. 

Ries,  H.  Clay  deposits  and  clay  industry  in  North  Caro- 
lina. Bulletin  13,  N.  C.  Geological  Survey,  157  pp. 
1897. 

Babcock,  E.  J.  Clays  of  economic  value  in  North  Dakota. 
1st  Rep.  N.  D.  Geological  Survey,  pp.  27-55.  1901. 

Orton,  E.  The  clays  of  Ohio  and  the  industries  estab- 
lished upon  them.  Vol.  5,  Reports  Ohio  Geological 
Survey,  pp.  643-721.  1884. 

Orton,  E.  The  clays  of  Ohio:  their  origin,  composition, 
and  varieties.  Vol.  7,  Reports  Ohio  Geological  Sur- 
vey, pp.  45-68.  1893. 

Ries,  H.  The  clay-working  industries  of  the  Pacific 
Coast  States.  Mines  and  Minerals,  vol.  20,  pp.  487- 
488.  1900. 

Hopkins,  T.  C.  Clays  of  western  Pennsylvania.  Appen- 
dix to  Ann.  Rep.  Pennsylvania  State  College  for  1897- 
98,  184  pp.  1898. 

Hopkins,  T.  C.  Clays  of  southeastern  Pennsylvania. 
Appendix  to  Ann.  Rep.  Pennsylvania  State  College  for 
1898-99,  76  pp.  1899. 

Hopkins,  T.  C.  Clays  of  the  Great  Valley  and  South 
Mountain  areas.  Appendix  to  Ann.  Rep.  Pennsylvania 
State  College  for  1899-1900,  45  pp.  1900. 

Woolsey,  L.  H.  Clays  of  the  Ohio  Valley  in  Pennsyl- 
vania. Bulletin  225,  U.  S.  Geological  Survey,  pp.  463- 
480.  1904. 

Sloan,  E.  A  preliminary  report  on  the  clays  of  South 
Carolina.  Bulletin  1,  South  Carolina  Geological  Sur- 
vey, 171  pp.  1904. 

Todd,  J.  E.  The  clay  and  stone  resources  of  South  Dakota. 
Eng.  and  Min.  Jour.,  vol.  66,  pp.  371.  1898. 

Eckel,  E.  C.  Stoneware  and  brick  clays  of  western 
Tennessee  and  northwestern  Mississippi.  Bulletin  213, 
U.  S.  Geol.  Survey,  pp.  382-391.  1903. 


CLAYS,  SHALES,  AND   SLATES.  363 

TEXAS.  Kennedy,  W.  Texas  clays  and  their  origin.  Science, 

vol.  22,  pp.  297-300.  1893. 

WASHINGTON.  Landes,  H.  Clays  of  Washington.  Vol.  1,  Rep.  Wash- 

ington Geol.  Survey,  pt.  2,  pp.  13-23.  1902. 

WISCONSIN.  Buckley,  E.  R.  The  clays  and  clay  industries  of  Wis- 

consin Bulletin  7,  Wisconsin  Geol.  Survey,  304  pp. 
1901. 

WYOMING.  Knight,  W.  C.  The  building  stones  and  clays  of  Wyoming. 

Eng.  and  Min.  Jour.,  vol.  66,  pp.  546-547.  1898. 

Slates. 

Slate  is,  so  far  as  origin  is  concerned,  merely  a  form  of  shale  in  which 
a  fine,  even,  and  parallel  cleavage  has  been  developed  by  pressure.  In 
composition,  therefore,  it  will  vary  exactly  as  do  the  shales  considered 
in  the  last  section,  and  so  far  as  composition  alone  is  concerned,  slate 
would  not  be  worthy  of  more  attention,  as  a  Portland-cement  mate- 
rial, than  any  other  shale. 

Commercial  considerations  in  connection  with  the  slate  industry, 
however,  make  slate  a  very  important  possible  source  of  cement  mate- 
rial. Good  roofing  slate  is  a  relatively  scarce  material  and  commands 
a  good  price  when  found.  In  the  preparation  of  roofing  slate  for  the 
market  so  much  material  is  lost  during  sawing,  splitting,  etc.,  that 
only  about  10  to  25  per  cent  of  the  amount  quarried  is  salable  as  slate. 
The  remaining  75  to  90  per  cent  is  of  no  service  to  the  slate-miner.  It 
is  sent  to  the  dump  heap,  and  is  a  continual  source  of  trouble  and  expense. 
This  very  material,  however,  as  can  be  seen  from  the  analyses  quoted 
below,  is  often  admirable  for  use  in  connection  with  limestone  in  a 
Portland-cement  mixture.  As  it  is  a  waste  product,  it  could  be  obtained 
very  cheaply  by  the  cement  manufacturer. 

Geographic  distribution  of  slates. — The  principal  areas  in  the  United 
States  in  which  roofing  slate  is  at  present  quarried  are  briefly  noted 
below.  For  more  detailed  information  on  the  subject,  reference  should 
be  made  to  the  papers  and  reports  listed  on  page  366. 

Beginning  in  the  northeast,  slates  are  extensively  quarried  in  the 
Brownsville-Monson  area  in  northern  Maine,  but  no  satisfactory  lime- 
stones occur  in  this  district  The  next  important  slate  area  lies  in 
western  Vermont  and  eastern  New  York,  a  region  well  supplied  with 
good  limestones.  In  New  Jersey  and  Pennsylvania  slates  are  worked 
just  north  of  the  Lehigh  cement-rock  belt,  as  noted  in  Chapter  XXIV. 
The  Peach  Bottom  slate  district,  located  in  southern  Pennsylvania  and 
northeastern  Maryland,  is  also  important,  but  is  poorly  supplied  with 


364 


CEMENTS,  LIMES,  AND  PLASTERS. 


limestone.  Isolated  slate  districts  occur  in  Virginia,  but  not  near 
limestone  areas.  In  eastern  Tennessee  and  northwestern  Georgia, 
however,  roofing  slates  and  non-magnesian  limestones  occur  in  close 
proximity;  and  in  the  Georgia  slate  district  a  Portland-cement  plant 
is  already  in  operation.  West  of  the  Mississippi,  good  slates  are  worked 
more  or  less  extensively  in  -  Minnesota,  Arkansas,  Utah,  and  California. 
Composition  of  slates. — The  composition  of  a  large  series  of  Ameri- 
can roofing  slates  from  various  localities  is  given  in  Table  164. 

TABLE  164 
ANALYSES  OF  AMERICAN  ROOFING  SLATES. 


I. 

2. 

3. 

4. 

5. 

6. 

7. 

Silica  (SiO  ) 

54  24 

56  42 

60  80 

67  70 

67  76 

59  84 

67  61 

Alumina  (A12O.,) 

24  71 

24  14 

22  00 

13  49 

14  12 

15  02 

13  20 

Iron  oxides  (Fe263,FeO) 
Lime  (CaO)         

8.39 
5  23 

4.46 
0  52 

10.50 
0  50 

2.75 

0  81 

5.52 
0  63 

5.96 
2  20 

6.56 
0  11 

Magnesia  (MgO)  

2  59 

2  28 

0.70 

1.29 

2.38 

3  41 

3  20 

Alkalies        

2.15 

8  68 

2.30 

4.91 

4.82 

5.60 

5  12 

Water  and  CO2 

(?) 

3  88 

1  80 

9  05 

3  61 

6  83 

3  42 

' 

8. 

9. 

10. 

11. 

12 

13. 

14. 

Silica  (SiO2)  

56  49 

68.62 

55.88 

58.37 

62.71 

60  65 

58  20 

Alumina  (A12O3)  
Iron  oxides  (Fe2O3,FeO) 
Lime  (CaO)             

11.59 
4.90 
5  11 

12.68 
4.20 
2  34* 

21.85 
9.03 
0  16 

21.98 
10.66 
0  30 

19.40 
2.18 
1  11 

16.87 
7.79 
1  91 

18.83 
5.78 
4  35 

Magnesia  (MgO)  

6  43 

3  76* 

1  49 

1  20 

1  73 

2  39 

3  51 

Alkalies    

4.29 

3  73 

4  10 

1  93 

4  74 

5  98 

3  20 

Water  and  CO2 

10  61 

4  47 

3  39 

4  42 

4  08 

3  63 

4  67 

1.  Monson,  Maine. 
2. 
3.  Lancaster,  Mass. 
4.  Hamburg,  N.  Y. 
5.  West  Pawlet,  Vt. 

*  Carbonate. 

6.  Pawlet,  Vt. 
7.  Poulteney,  N.  Y. 
8.  Raceville,  N.  Y. 
9.  Bangor,  Pa. 
10.  Peach  Bottom,  Pa.-Md.  belt. 

11.  Peach  Bottom,  Pa.-Md.  belt. 
12.  Martinsburg,  W.  Va. 
13.  Arvonia,  Va. 
14.  Rockmart,  Ga. 

TABLE  165. 
COMPOSITION  OF  AMERICAN  ROOFING  SLATES. 


Maximum. 

Average. 

Minimum. 

Silica  (SiO,)  

68.62 
24.71 
10.66 
5.23 
6.43 
8.68 

60.64 
18.05 
6.87 
1.54 
2.60 
4.74 
0.38 
1.47 
3.51 
0.62 

54.05 
9.77 
2.18 
0.00 
0.12 
1.93 

Alumina  (A12O3)       

Iron  oxides  (FeO,Fe2O3)  

Lime  (CaO)  

Magnesia  (MgO)  

Alkalies  (K2O,Na2O)  

Ferrous  sulphide  (FeS2)  

Carbon  dioxide  (CO2)  

Water  of  combination.  .  ..,  

Moisture,  below  110°  C  

CLAYS,  SHALES,  AND  SLATES. 


365 


Slates  used  in  cement-manufacture. — Only  one  American  Portland- 
cement  plant  is  at  present  using  roofing  slate  as  one  of  its  raw  mate- 
rials, and  this  plant  is  of  quite  recent  construction.  It  is  that  of  the 
Southern  States  Portland  Cement  Company,  and  is  located  about  half 
a  mile  east  of  the  village  of  Rockmart,  Polk  County,  Ga.  The  Port- 
land cement  manufactured  here  is  made  from  a  mixture  of  pure  lime- 
stone and  slate,  both  of  which  materials  occur  in  the  immediate  vicinity 
of  the  plant. 

Hard  blue  slates,  which  have  been  extensively  quarried  for  struc- 
tural purposes,  outcrop  on  the  hills  south  of  Rockmart.  These  slates 
are  of  Ordovician  age  and  have  been  described  as  the  "Rockmart 
slates"  by  Hayes.  East  of  the  town  the  surface  rock  is  the  "Chicka- 
mauga  limestone,"  which  here  contains  beds  of  pure  non-magnesian 
limestone  which  have  been  quarried  at  several  points  in  the  vicinity 
and  burned  into  lime. 

The  cement  company  purchased  the  property  of  the  old  Georgia 
Slate  Company,  about  half  a  mile  southwest  of  Rockmart,  and  car- 
ried on  extensive  operations  with  the  diamond-drill.  The  intention 
was  to  quarry  the  slate,  sell  as  slate  the  portions  best  suited  for  that 
use,  and  utilize  the  scrap  and  waste  in  the  manufacture  of  cement. 
The  quarries  from  which  the  limestone  is  obtained  are  located  half  a 
mile  east  of  town,  near  the  mill.  The  president  of  the  cement  com- 
pany is  Mr.  W.  F.  Cowhan,  who  is  also  connected  with  the  Peninsular 
Portland  Cement  Company,  of  Jackson,  Mich.,  and  the  National  Port- 
land Cement  Company,  of  Durham,  Ontario. 

TABLE  166. 
ANALYSES  OF  SLATE  USED  FOR  PORTLAND  CEMENT,  ROCKMART,  GA. 


1. 

2. 

Silica  (SiO2)  

57  40 

58.20 

Alumina  (A12O3)  

23  65 

18.83 

Iron  oxide  (CaO)  

4  45 

5.78 

Lime  (CaO) 

3  23 

4  35 

Magnesia  (MgO) 

3  23 

3  51 

Alkalies  (K2O,Na2O) 

n  d 

3.20 

Sulphur  (S) 

n  d 

0.49 

Carbon  (C) 

n  d 

0  82 

Carbon  dioxide  (CO2)  

0.60 

Water 

>      6  .  80    \ 

4  07 

1.  J.  F.  Davis,  analyst.     Privately  communicated. 

2.  Slocum  and  Vandeventer,  analysts.     18th  Ann.  Rep.  U.  S.  Geol.  Survey,  pt.  5. 


366  CEMENTS,  LIMES,  AND  PLASTERS. 

References  on  slates. — The  following  papers  contain  material  of 
interest  in  connection  with  the  composition,  distribution,  and  structure 
of  slate. 

Dale,  T.  N.     The  slate  belt  of  eastern  New  York  and  western  Vermont.     19th 

Ann.  Rep.  U.  S.  Geol.  Survey,  pt.  3,  pp.  153-307.     1899. 
Dale,  T.  N.    The  slate  industry  at  Slatjiigton,  Pa.,  and  Martinsburg,  W.  Va. 

Bulletin  213,  U.  S.  Geol.  Survey;  pp.  361-364. 
Dale,  T.  N.     The   slate   deposits   and   slate   industry  of  the  United  States. 

Bulletin  — ,  U.  S.  Geol.  Survey.     (In  press.) 

Da  vies,  D.  C.     Slate  and  slate  quarrying.     12mo,  181  pp.     London,  1899. 
Eckel,  E.  C.     Slate  deposits  of  California  and  Utah.     Bulletin  225,  U.  S.  Geol. 

Survey,  pp.  417-422.     1904. 
Eckel,  E.  C.     The  chemical  composition  of  American  shales  and  roofing  slates. 

Journal  of  Geology,  vol.  12,  pp.  25-29.     1904. 


CHAPTER  XXVIII. 
EXCAVATING  THE  RAW  MATERIALS. 

THE  excavation  of  the  raw  materials  is  the  first  step  toward  the 
actual  manufacture  of  Portland  cement,  and  the  one  concerning  which 
least  has  been  published.  Local  conditions  enter  into  this  preliminary 
phase  to  such  an  extent  that  few  general  statements  can  be  made  con- 
cerning it.  To  a  large  extent,  each  separate  deposit  of  raw  material 
is  an  individual  proposition  to  be  handled  best  in  a  way  peculiar  to 
itself.  The  natural  raw  materials  which  are  at  present  used  in  the 
American  Portland-cement  industry  are  worked  by  one  of  three  gen- 
eral methods.  These  are:  (1)  quarrying  or  digging  from  open  pits; 
(2)  mining  from  underground  workings,  and  (3)  dredging  from  deposits 
covered  by  water.  Occasionally  the  cement  manufacturer  will  have 
an  opportunity  to  choose  his  general  method  of  working  the  deposit, 
in  which  case  his  choice  will  depend  partly  on  the  physical  characters 
of  the  material  to  be  excavated  and  partly  on  the  topographic  and 
geologic  conditions.  Usually,  however,  he  will  have  no  opportunity 
to  choose  a  method,  for  in  any  given  case  one  of  the  methods  will  be 
so  evidently  the  only  possible  mode  of  handling  the  material  as  to  leave 
no  room  for  other  considerations. 

The  three  different  general  methods  of  excavation  will  first  be  briefly 
considered,  after  which  the  cost  of  excavating  various  raw  materials 
will  be  discussed  in  some  detail. 

Quarrying. 

In  the  following  pages  the  term  "  quarrying "  will  be  used  to  cover 
all  methods  of  obtaining  raw  materials  from  open  excavations — quarries, 
cuts,  or  pits — whether  the  material  excavated.be  a  limestone,  a  shale, 
or  a  clay.  Quarrying  is  the  most  natural  and  common  method  of 
excavating  the  raw  materials  for  cement-manufacture.  If  marl,  which 
is  usually  worked  by  dredging,  be  excluded  from  consideration,  it  is 
probably  within  safe  limits  to  say  that  95  per  cent  of  the  raw  mate- 
rials used  at  American  Portland-cement  plants  are  obtained  by  quarry- 

367 


368  CEMENTS,  LIMES,  AND  PLASTERS. 

ing.  If  marls  be  included,  the  percentages  excavated  by  the  different 
methods  would  probably  be  about  as  follows:  quarrying,  88  per  cent; 
dredging,  10  per  cent;  mining,  2  per  cent. 

Stripping.— When  a  limestone  is  being  quarried,  the  opening  should 
be  so  located  as  to  give  as  little  stripping  as  possible  in  proportion  to 
the  available  rock;  for  in  this  case  the  stripping  is  merely  dead  work, 
adding  greatly  to  the  expense  of  the  product.  In  dealing  with  a  shale- 
bed,  the  "stripping"  is  usually  merely  weathered  shale  and  can  be 
used  as  well  as  the  harder  portions  of  the  deposit. 


FIG.  71. — Stripping  a  flat,  shallow  bed. 

A  very  thick  bed  of  limestone,  or  a  bed  of  moderate  thickness  lying 
almost  horizontally,  will  not  give  as  much  stripping  per  ton  of  good 
rock  as  a  thin  bed  or  a  bed  dipping  at  a  high  angle.  In  handling  com- 
paratively thin  earth  stripping  in  flat  country,  scrapers  or  excavators 
may  be  used  (Fig.  71);  while  at  one  cement-plant  a  heavy  soil  cover 
on  a  quarry  near  a  river-bank  is  removed  by  hydraulicking.  This  last 
process  is  also  used  in  several  large  brick-plants. 

Quarry  practice. — In  most  of  the  quarries  for  cement  rock  or  lime- 
stone, the  rock  is  opened  up  on  a  low  side-hill,  so  as  to  give  a  long  work- 
ing-face with  light  stripping  and  as  little  grade  as  possible  in  the  work- 
ings. The  rock  is  blasted  down  in  one  or  more  benches,  according  to 
the  height  of  face  exposed,  and  the  larger  pieces  are  sledged  or  reblasted 
to  manageable  size  by  men  placed  along  the  working-face.  It  is  then 
loaded  either  into  one-horse  carts  or  into  small  cars  running  on  tem- 
porary tracks  laid  close  up  to  the  face.  In  the  former  case  the  carts 
are  driven  to  a  dump  and  loaded  into  cars;  in  the  latter  case  the  cars 
are  drawn  by  horses  or  pushed  by  men  to  a  turntable.  This  turntable 


EXCAVATING  THE  RAW  MATERIALS. 


369 


FIG.  72. — View  of  typical  quarry. 


FIG.  73. — Temporary  tracks  laid  to  face. 


370 


CEMENTS,  LIMES,  AND  PLASTERS. 


is  a  comparatively  fixed  affair,  located  far  enough  away  from  the  work- 
ing-face to  avoid  damage  from  blasting.  Here  the  cars  are  attached 
to  a  cable  or  to  a  locomotive  and  hauled  to  the  mill. 


FIG.  74. — Cableway  in  cement-rock  quarry. 

Occasionally  an  aerial  cableway  is  used  for  transporting  the  mate- 
rial to  the  mill.  This  is  shown  hi  the  two  views  of  a  cement-rock  quarry 
given  in  Figs.  74  and  75. 

Working  in  levels. — In  quarries  containing  several  beds  of  rock 
differing  greatly  in  composition  and  lying  horizontally,  tracks  are  often 
run  in  on  different  levels,  so  as  to  insure  that  each  car  or  cart  shall  con- 
tain only  one  kind  of  rock.  This  practice  is  exemplified  in  the  shale-pit 
shown  in  Fig.  76.  A  similar  plan  is  followed  in  working  the  quarry 
partly  shown  in  Fig.  77,  which  contains  several  heavy  beds  of  limestone 
intercalated  with  workable  but  thinner  layers  of  shale. 

Use  of  steam-shovels. — In  a  few  limestone  and  cement-rock  quarries 
a  steam-shovel  is  employed  to  load  the  blasted  rock  into  the  cars,  and 
in  shale  quarries  this  use  of  steam-shovels  is  more  frequent.  In  cer- 
tain clay-  and  shale-pits,  where  the  material  is  of  suitable  character,  the 
steam-shovel  can  be  employed  to  do  all  the  work,  both  excavating  and 
loading  the  materials. 


EXCAVATING  THE  RAW  MATERIALS. 


371 


FIG.  75. — Cableway  in  cement-rock  quarry. 


FIG.  76. — Shale-pit  worked  in  two  levels. 


372 


CEMENTS,  LIMES,  AND  PLASTERS. 


FIG.  77. — Hoisting  from  quarry  worked  in  levels. 


FIG.  78. — Steam-shovel  in  cement-rock  quarry. 


EXCAVATING  THE   RAW  MATERIALS. 


373 


Steam-shovels  are  in  use  at  the  plant  of  the  Purington  Paving  Brick 
Company,  at  Galesburg,  111.  Here  a  bank  of  firm  shale  is  drilled,  shaken 
with  black  powder,  and  then  handled  entirely  by  steam-shovel.  The 
following  detailed  figures  of  cost  have  been  recently  published  by  Mr. 
C.  W.  Purington. 

The  figures  cover  the  handling  of  17,422  cubic  yards  of  shale  in 
one  month  of  twenty-six  nine-hour  days.  This  shale  was  dug  from  a 
50-foot  bank  with  a  Model  90  Barnhart  shovel  with  2-yard  dipper. 
It  was  delivered  to  twenty  2-yard  cars  and  trammed  in  two  directions 
(1500  and  2000  feet  respectively)  to  the  bottoms  of  two  inclines.  It  was 
then  hoisted  by  cable  to  hoppers  placed  at  an  elevation  of  20  feet  above 
the  track  and  dumped  into  the  hoppers. 


TABLE  167. 
DETAILED  COSTS  OF  STEAM-SHOVEL  WORK. 


(PURINGTON.) 


Per  Month. 

Per  Yard, 
Cents. 

Labor  • 
Fuel      - 

1  engineer  on  shovel     

$110.00 
85.00 
52.65 
128.85 
80.00 
46.80 
93.60 

1  craneman     

1  fireman  at  22  \  cents  per  hour    

3  trackmen  at  17^  cents  per  hour  

1  engineer  on  locomotive 

1  switchman  at  20  cents  per  hour 

2  hoistmen  at  20  cents  per  hour 

Total  labor      

$596.90 
78.00 
26.00 
52.00 

0.0343 

1  \  tons  coal  per  day  at  $2.00  per  ton  for  shovel.  . 
\  ton  coal  per  day  at  $2.00  per  ton  for  locomotive 
1    ton  coal  per  aay  at  $2.00  per  ton  for  two  hoists. 

Total  fuel  

$156.  CO 

0.0089 

Total  costs,  labor  and  fuel  

$752.90 

0.0432 

These  figures  do  not  include  charges  for  superintendence,  oil,  waste, 
etc.  If  these  be  included,  the  cost  of  the  steam-shovel  work  will  be 
about  5  cents  per  cubic  yard.  If  the  cost  of  drilling  and  blasting  be 
added,  the  total  cost  of  handling  the  shale  from  the  bank  to  the  hop- 
pers may  be  about  6  cents  per  cubic  yard.  Of  this  the  blasting,  dig- 
ging, etc.,  amounts  to  about  4  cents  per  yard,  while  the  tramming,  hoist- 
ing, and  dumping  will  amount  to  the  remaining  2  cents. 

In  handling  shales,  steam-shovels  are  usually  very  effective  exca- 
vators, for  here  the  material  is  physically  homogeneous  and  requires 
only  one  light  blasting  to  break  it  into  fragments  that  can  be  readily 
handled  by  the  shovel.  This  is  well  brought  out  by  the  itemized  costs 
given  above  for  the  Galesburg  shale  quarry. 


374 


CEMENTS,  LIMES,  AND  PLASTERS. 


When  dealing  with  the  Lehigh  district  cement  rock,  the  steam- 
shovel  is  not  quite  so  satisfactory,  for  much  of  the  rock  will  require 
hand  sledging  after  being  blasted  before  it  can  be  conveniently  handled 
by  the  shovel.  The  hard  limestones  are  still  more  intractable,  and 
often  require  not  only  sledging  but  reblasting.  This,  of  course,  greatly 
decreases  the  financial  effectiveness  of  Jjie  shovel,  and  in  many  quarries 
will  entirely  prevent  its  use.  In  shallow  quarries  vertical  seams  filled 


FIG.  79. — Steam-shovel  handling  limestone. 

with  clay,  soil,  or  other  wash  from  the  surface  may  greatly  hinder  the 
work  of  the  shovel;  and  in  quarries  where  rock  is  so  mixed  in  compo- 
sition as  to  require  sorting  the  shovel  is  worse  than  useless. 

Crushing  and  drying  in  the  quarry. — The  rock  is  usually  transported 
directly  to  the  mill  just  as  quarried,  except  that  the  larger  masses  are 
sledged  to  convenient  size  for  handling.  At  a  few  quarries,  however, 
a  crushing-plant  is  installed  at  the  quarry,  and  the  rock  is  sent  as  crushed 
stone  to  the  mill.  Several  of  the  quarries  in  question  sell  a  certain 
portion  of  their  product  as  road  metal,  which,  of  course,  reduces  the 
cost  of  the  finer  material  which  is  sent  to  the  cement-plant. 

A  few  plants  have  also  installed  their  driers  at  the  quarry  and  dry 
the  stone  before  shipping  it  to  the  mill.  This  practice,  shows  a  saving 
in  mill  space,  but  otherwise  it  seems  to  have  little  to  recommend  it. 


EXCAVATING  THE  RAW  MATERIALS.  375 

In  the  cases  where  a  wet  clay  or  shale  is  quarried  some  distance 
away  from  the  mill  the  saving  in  transportation  charges,  due  to  dry- 
ing at  the  quarry,  would,  of  course,  be  considerable. 

Mining. 

The  term  "mining"  will  be  used,  in  distinction  from  "quarrying", 
to  cover  methods  of  obtaining  any  kind  of  raw  material  by  underground 
workings,  through  shafts  or  tunnels.  Mining  is  rarely  employed 
in  excavating  materials  of  such  low  value  per  ton  as  the  raw  materials 
for  Portland-cement  manufacture.  Occasionally,  however,  when  a  thin 
bed  of  limestone  or  shale  is  being  worked,  its  dip  will  carry  it  under 
such  a  thickness  of  other  strata  as  to  make  mining  cheaper  than 
stripping  and  quarrying  for  that  particular  case. 

Mining  is  considerably  more  expensive  work  than  quarrying,  but 
.there  are  a  few  advantages  about  it  that  serve  to  counterbalance  the 
greater  cost  per  ton  of  raw  material.  A  mine  can  be  worked  steadily 
and  economically  in  all  kinds  of  weather,  while  an  open  cut  or  quarry 
is  commonly  in  a  more  or  less  unworkable  condition  for  about  three 
months  of  the  year.  Material  won  by  mining  is,  moreover,  always  dry 
and  clean. 

Dredging. 

The  term  "dredging"  will  be  here  used  to  cover  all  methods  of 
excavating  soft,  wet,  raw  materials.  The  fact  that  the  materials  are 
wet  implies  that  the  deposit  occurs  in  a  basin  or  depression,  and  this 
in  turn  implies  that  the  mill  is  probably  located  at  a  higher  elevation 
than  the  deposit  of  raw  material,  thus  necessitating  uphill  transporta- 
tion to  the  mill. 

The  only  raw  material  for  Portland-cement  manufacture  that  is 
extensively  worked  by  dredging  in  the  United  States  is  marl.  Occa- 
sionally the  clay  used  is  obtained  from  deposits  overlain  by  more  or 
less  water;  but  this  is  rarely  done  except  where  the  marl  and  clay  are 
interbedded  or  associated  in  the  same  deposit. 

A  marl  deposit,  in  addition  to  containing  much  water  diffused  through- 
out its  mass,  is  usually  covered  by  a  more  or  less  considerable  depth 
of  water.  This  will  frequently  require  the  partial  draining  of  the  basin 
in  order  to  get  tracks  laid  near  enough  to  be  of  service. 

In  dredging  marl  the  excavator  is  frequently  mounted  on  a  barge 
which  floats  in  a  channel  resulting  from  previous  investigation.  Occa- 
sionally, in  deposits  which  either  were  originally  covered  by  very  little 


376 


CEMENTS,  LIMES,  AND  PLASTERS. 


water  or  have  been  drained,  the  shovel  is  mounted  on  a  car  running 
on  tracks  laid  along  the  edge  of  the  deposit. 

The  material  brought  up  to  the  dredge  may  be  transported  to  the 
mill  in  two  different  ways,  the  choice  depending  largely  upon  the  manu- 
facturing processes  in  use  at  the  plant.  At  plants  using  dome  or  chamber 
kilns,  or  where  the  marl  is"  to  be  drjfed  before  sending  to  the  kiln,  the 
excavated  marl  is  usually  loaded  by  the  shovel  on  cars  and  hauled 
to  the  mill  by  horse  or  steam  power.  At  normal  marl-plants  using 
a  very  wet  mixture  it  is  probable  that  the  second  ^method  of  transpor- 
tation is  more  economical.  This  consists  of  dumping  the  marl  from 
the  excavator  into  tanks,  adding  sufficient  water  to  make  it  flow  readily, 
and  pumping  the  fluid  mixture  to  the  mill  in  pipes. 


FIG.  80.  — Dredge  at  marl-plant. 

Marl-pumping. —  The  following  description  of  the  Harris  system 
of  pumping  marl  from  the  lake  to  the  mill  is  taken  from  the  catalogue 
of  the  Allis-Chalmers  Company: 

"This  method  of  handling  marl  by  compressed  air  is  now  in  great 
favor,  and  many  plants  have  been  and  are  now  being  installed  in  cement 
works  in  this  country  and  Canada. 

"The  essential   features   are   given   in   the   diagram  herewith,   and 


EXCAVATING  THE  RAW  MATERIALS. 


377 


comprise  the  pump-tanks,  air-compressor,  automatic  switch,  and  piping. 
There  are  no  floats.  There  are  no  air-valves  outside  the  engine-room. 

"The  air  is  not  allowed  to  escape  after  doing  its  work.  The  expan- 
sive force  of  the  air  is  used  in  the  compression  cylinder  of  the  com- 
pressor, thus  giving  back  the  greater  part  of  its  energy  to  the  compressor. 

"Suppose  the  compressor  to  be  in  operation  with  switch  set  as  in 


--^-^  Water  SujjpOy 
FIG.  81. — Harris  system  of  marl-pumping. 

the  figure,  the  air  will  be  drawn  out  of  the  right-hand  tank  and  forced 
into  the  left-hand  tank,  and  in  so  doing  will  draw  marl  into  the  former 
and  force  it  out  of  the  latter. 

"The  charge  of  air  in  the  system  is  so  adjusted  that  when  one  tank 
is  emptied  the  other  is  just  filled.  At  that  moment  the  switch  will 
reverse  the  pipe  connections  so  that  action  in  the  tanks  will  be  reversed. 

"The  switch  is  adjustable  and  can  be  set  or  regulated  while  the 
pump  is  in  operation." 

For  further  data,  reference  should  be  made  to  a  paper  by  E.  G. 
Harris,  published  in  "Mines  and  Minerals,"  vol.  15,  pp.  513-514.  May, 
1905. 


378  CEMENTS,  LIMES,  AND  PLASTERS. 


Cost  of  Raw  Materials  at  Mill. 

The  most  natural  way,  perhaps,  to  express  the  cost  of  the  raw 
materials  delivered  at  the  mill  would  be  to  state  it  as  being  so  many 
cents  per  ton  or  cubic  yard  .of  raw  ^material ;  and  this  is  the  method 
followed  by  quarrymen  or  miners  in  general.  To  the  cement  manufac- 
turer, however,  such  an  estimate  is  not  so  suitable  as  one  based  on  the 
cost  of  raw  materials  per  ton  or  barrel  of  finished  cement. 

Loss  on  drying,  etc. — In  the  case  of  hard  and  comparatively  dry 
limestones  or  shales,  it  may  be  considered  that  the  raw  mixture  loses 
33  J  per  cent  in  weight  on  burning.  Converting  this  relation  into  pounds 
of  raw  material  and  of  clinker,  we  find  that  600  pounds  of  dry  raw  material 
will  make  about  400  pounds  of  clinker.  Allowing  something  for  other 
losses  in  the  process  of  manufacture,  it  is  convenient  and  sufficiently 
accurate  to  estimate  that  600  pounds  of  dry  raw  material  will  give  one 
barrel  of  finished  cement.  These  estimates  must  be  increased  if  the 
raw  materials  carry  any  appreciable  amount  of  water.  Clays  will  fre- 
quently contain  15  per  cent  or  more  of  water;  while  soft,  chalky  lime- 
stones, if  quarried  during  weather,  may  carry  as  high  as  15  to  over  20 
per  cent.  A  Portland-cement  mixture  composed  of  a  pure  chalky  lime- 
stone and  a  clay  might,  therefore,  average  10  to  20  per  cent  of  water,  and 
consequently  about  700  pounds  of  such  a  mixture  would  be  required 
to  make  one  barrel  of  finished  cement. 

With  marls  the  loss  on  drying  and  burning  is  much  greater. 
Russell  states  *  that  according  to  determinations  made  by  E.  D.  Camp- 
bell, 1  cubic  foot  of  marl  as  it  usually  occurs  in  the  natural  deposits 
contains  about  47J  pounds  of  lime  carbonate  and  48  pounds  of  water. 
In  making  cement  from  a  mixture  of  marl  and  clay,  therefore,  it  would 
be  necessary  to  figure  on  excavating  and  transporting  over  1000  pounds 
of  raw  material  for  every  barrel  of  finished  cement. 

From  the  preceding  notes  it  will  be  understood  that  the  cost  of 
raw  materials  at  the  mill  per  barrel  of  cement  will  vary  not  only  with 
the  cost  of  excavation,  but  with  the  kind  of  materials  in  use. 

Costs  of  quarrying  or  mining.— In  dealing  with  hard,  dry  materials 
extracted  from  open  quarries  near  the  mills,  the  cost  of  raw  materials 
may  vary  between  8  cents  and  15  cents  per  barrel  of  cement.  The 
lower  figure  named  is  probably  about  the  lowest  attainable  with  good 
management  and  under  favorable  natural  conditions;  the  higher  figure 


*  22d  Ann.  Rep.  U.  S.  Geol.  Survey,  pt.  3,  p.  657. 


EXCAVATING  THE  RAW  MATERIALS.  379 

is   probably  a  maximum  for  fairly  careful  management  of  a  difficulv 
quarry  under  Eastern  labor  conditions. 

At  one  Portland-cement  plant  in  the  Middle  States  a  20-foot  lime- 
stone-bed, overlain  by  10  to  15  feet  of  shale  and  soil,  is  worked  in  open 
cut.  When  this  work  was  handled  by  contract,  18  cents  per  cubic 
yard  was  paid  for  stripping,  and  23  cents  per  ton  for  quarrying  rock. 
Haulage  to  the  mill,  only  a  quarter  of  a  mile  away,  cost  about  4  cents 
per  ton,  owing  to  local  difficulties.  Quarry  laborers  here  were  worth 
$1.50  per  day,  and  the  following  data  on  actual  cost  of  quarrying  were 
obtained  from  one  of  the  contractors.  The  items  cover  labor  and  sup- 
plies for  two  men  for  two  weeks,  during  which  time  the  pair  got  out 
300  tons  of  limestone. 

10  Ibs.  dynamite  at  $0. 14  per  Ib $1 . 40 

I  box  caps  at  $0 . 75  per  box 0.19 

1  keg  powder  at  $1 . 50'per  keg 1 . 50 

100  feet  fuse  at  $0.45  per  100  feet 0.45 

Repairs,  sharpening,  etc 0 . 60 

24  days'  labor  at  $1 . 50  per  day 36.00 

Cost  of  quarrying  300  tons  limestone $40 . 14 

Cost  of  quarrying,  per  ton  limestone 0 . 13  f 

"     ' '  stripping,     ' '     "  "      0.07 

"     "  hauling,        "     "  "        0.04 

Total  cost  limestone  per  ton .     $0 . 24 

When  it  is  necessary  to  mine  the  materials,  the  cost  will  be  some- 
what increased.  Natural-cement  rock  has  been  mined  at  a  cost  equiv- 
alent to  10  cents  per  barrel  of  cement;  but  the  figure  is  attained  under 
particularly  favorable  conditions.  The  cost  of  mining  and  transpor- 
tation may  reach  from  this  figure  up  to  20  cents  per  barrel. 

Costs  of  marl-dredging. — The  costs  of  dredging  and  handling  marl 
at  several  American  cement-plants  are  given  below : 

Plant  1.  The  marl-  and  clay-pits  are  about  3J  miles  by  track  from 
the  mill.  Both  materials  are  covered  by  J  to  1  foot  of  earth,  but 
no  water.  A  long  cut  is  made  into  the  deposit,  into  which  cut  cars 
are  run  on  light  tracks.  These  cars,  containing  about  3000  Ibs.  of 
marl,  are  loaded  by  hand.  The  contract  price  for  loading  is  8  cents 
per  car  for  marl  and  14  cents  per  car  for  clay,  and  these  prices  are  equiv- 
alent to  a  pay  of  $3.00  to  $4.00  per  day  of  12  hours  for  each  laborer 
loading.  Two  engines  are  used,  one  for  switching  and  making  up  trains 
at  the  marl-  and  clay-pits,  the  other  for  hauling  the  trains  to  the 
mill.  The  total  cost  for  sufficient  marl  and  clay  for  1200  barrels 
cement  is: 


380  CEMENTS,  LIMES,  AND  PLASTERS. 

2  engineers  at  $1 . 50 S3 . 00 

2  firemen  at  $1 . 25 2 . 50 

400  cars  marl  at  $0 .08 32 .00 

80  cars  clay  at  $0. 14 11 .20 

2000  Ibs.  coal  at  $2 . 40  per  ton 2 . 40 


Total  cost  marl  and  clay  for  1200  bbls.  cement . .   $51 . 10 
Cost  marl  and  clay  for  1  bb£  cement 0 .043 

Plant  %.  The  marl  and  clay  occur  in  a  swamp  half  a  mile  from  the 
mill.  The  surface  material  is  2  to  3  feet  black  loam;  this  is  underlain 
by  9  feet  marl,  and  this,  in  turn,  by  the  clay.  A  dredge  with  a  lo- 
ll.P.  engine  and  a  crew  of  two  men  handles  the  marl,  digging  enough 
for  240  barrels  cement  in  ten  hours.  A  smaller  dredge  with  orange- 
peel  bucket,  run  by  one  man,  handles  the  clay.  One  locomotive  hauls 
the  material  to  the  plant  over  tracks  laid  alongside  the  excavations. 
Total  costs  per  day  for  a  240-barrel  plant  are  as  follows : 

1  marl-dredge  runner $1 . 50 

1  leverman,  marl  dredge 1 . 25 

1  clay-dredge  runner 1 . 25 

1  locomotive  engineer 1 . 50 

350  Ibs.  coal  for  marl  dredge  at  $2 . 20  per  ton 0 . 38 $ 

150  Ibs.  coal  for  clay  dredge  at  $2 . 20  per  ton 0 . 16 \ 

500  Ibs.  coal  for  locomotive  at  $2 . 20  per  ton 0 . 55 

Cost  of  clay  and  marl  for  240  barrels  cement ...   $6 . 50 
Cost  of  clay  and  marl  for  1  barrel  cement 0.027 

Plant  S.  Marl  dredged  from  lake  one  quarter  mile  from  mill.  This  is 
done  by  contract,  the  marl  being  delivered  to  the  mill  for  5^  cents  per 
cubic  yard.  This  price  is  about  equivalent  to  $0.018  per  barrel  of 
cement  for  marl  alone.  In  this  case  the  dredging-plant  was  bought  and 
installed  at  .the  expense  of  the  company,  but  the  contractor  pays  all 
the  current  expenses,  including  pay,  repairs,  coal,  etc. 

Plant  4-  Marl  dredged  from  lake  one  third  mile  from  mill  by  a 
dredge  operating  a  1  ^-cubic-yard  orange-peel  bucket.  The  marl  is  fed 
through  a  stone  separator  and  then  pumped  to  the  mill  on  Harris  system. 
Total  cost  is  about  as  follows: 

2  men  at  $1.50 S3. 00 

3  men  at  $1 . 25 3 . 75 

2|  tons  coal  at  $2. 40 6.00 

Total  cost  of  marl  for  500  barrels  cement $12 . 75 

Cost  of  marl  for  1  barrel  cement 0. 025 


EXCAVATING  THE  RAW  MATERIALS.  381 

The  costs  above  cited  show  the  cheapness  with  which  marl  and  clay 
can  be  excavated.  The  total  costs  of  raw  material  at  a  wet-process 
plant  may  therefore  range  from  3  to  6  cents  per  barrel  of  cement. 

References  on  quarrying,  etc. — The  following  books  and  papers 
contain  data  of  interest  on  methods  and  costs  of  quarrying,  etc. 

Crane,  W.  A.  Shale  Mine  at  La  Harpe,  Kansas.  Mines  and  Minerals,  Dec., 
1902,  pp.  217-218. 

De  Kalb,  C.  Manual  of  Explosives.  16mo,  126  pp.  Ontario  Bureau  of  Mines, 
1900. 

Foster.  C.  Le  Neol.     Elements  of  Mining  and  Quarrying.     12mo,  321  pp.    1903. 

Gillette,  H.  P.     Earthwork  and  Its  Cost.     12mo,  244  pp.     New  York,  1903. 

Gillette,  H.  P.  Rock  Excavation:  Methods  and  Cost.  12mo,  376  pp.  New 
York,  1904. 

Green,  N.  M.  [Cost  of  raw  materials  in  cement  manufacture.]  Engineering 
Record,  Jan.  23,  1904. 

Guttmann,  O.     Blasting.     8vo,  179  pp.     London,  1892. 

Harris,  E.  G.  The  Harris  System  of  Pumping  with  Compressed  Air.  Mines 
and  Minerals,  vol.  25,  pp.  513-514,  May,  1905. 

Knight,  W.  B.  Quarrying  Limestone  at  Rockland,  Maine.  Mines  and  Min- 
erals, August,  1899. 


CHAPTER  XXIX. 

CALCULATION   AND   CONTROL   OF   THE   MIX. 

I* 

IF,  as  in  the  present  volume,  we  exclude  from  consideration  the 
go-called  "natural  Portlands"  (see  page  215),  Portland  cement  may  be 
regarded  as  being  entirely  an  artificial  product,  obtained  by  burning 
to  semi -fusion  an  intimate  mixture  of  pulverized  materials,  this  mix- 
ture containing  lime,  silica,  and  alumina  varying  in  proportion  only 
within  certain  narrow  limits,  and  by  crushing  finely  the  clinker  resulting 
from  this  burning. 

If  this  restricted  definition  of  Portland  cement  be  accepted,  four 
points  may  be  regarded  as  being  of  cardinal  importance  in  its  manu- 
facture. These  are: 

1.  The  cement  mixture  must  be  of  the  proper  chemical  compo- 

sition. 

2.  The  materials  of  which  it  is  composed  must  be  carefully  ground 

and  intimately  mixed  before  burning  in  order  to  insure  that 
chemical  combination  shall  take  place  after  calcination. 

3.  The  burning   must  be  conducted  at  the  proper  temperature, 

which  varies  considerably  according  to  the  chemical  com- 
position of  the  mixture,  and  the  length  of  time  during  which 
it  is  subjected  to  the  burning  process. 

4.  After  burning,   the  resulting  clinker  must  be  finely  ground. 

In  this  and  the  succeeding  chapters  these  points  will  be  taken  up 
separately  and  in  some  detail. 

The  present  chapter  deals  with  the  calculations  and  arrangements 
necessary  for  insuring  the  correctness  of  the  cement  mixture.  It,  there- 
fore, includes  discussions  of  the  theoretical  and  practical  considera- 
tions which  determine  the  proportions  of  the  mixture.  Among  these 
considerations  are  the  theoretical  composition  and  constitution  of  Port- 
land cement;  the  influence  of  various  normal  constituents  on  the  prop- 
erties of  the  mixture;  the  influence  of  fuel  ash  and  other  accidental 
impurities;  and  the  methods  of  calculating  and  controlling  the  mix  in 

actual  practice. 

382 


CALCULATION  AND  CONTROL  OF  THE  MIX.  383 

Theoretical  Composition  of  Portland  Cement. 

During  recent  years  much  attention  has  been  paid  by  various  inves- 
tigators to  the  constitution  of  Portland  cement.  The  chemical  com- 
position of  any  particular  sample  can,  of  course,  be  readily  determined 
by  analysis,  and  by  comparison  of  a  number  of  such  analyses,  general 
statements  can  be  framed  as  to  the  range  in  composition  of  good  Portland 
cements.  This  subject  is  discussed  further  in  Chapter  XXXVIII, 
where  a  large  number  of  analyses  are  presented. 

Chemical  analyses  will  determine  what  ingredients  are  present,  and 
in  what  percentages,  but  other  methods  of  investigation  are  necessary 
to  ascertain  in  what  manner  these  ingredients  are  combined.  A  summary 
of  the  more  important  practical  results  brought  out  by  these  investiga- 
tions on  the  constitution  of  Portland  cement  will  be  given  in  the 
present  chapter,  while  in  Chapter  XXXVIII  a  more  detailed  discussion 
of  the  problem  will  be  presented,  as  well  as  references  to  the  principal 
papers  on  the  subject. 

It  would  seem  to  be  firmly  established  that  in  a  well-burned  Port- 
land cement  much  of  the  lime  is  combined  with  most  of  the  silica 
to  form  the  compound  3CaCO,Si02, — tricalcic  silicate.  To  this  com- 
pound is  ascribed,  in  large  measure,  the  hydraulic  properties  of  the 
cement;  and  in  general  it  may  be  said  that  the  value  of  a  Portland 
cement  increases  directly  as  the  proportion  of  3CaO,SiO2-  The  ideal  Port- 
land cement,  toward  which  cements  as  actually  made  tend  in  compo- 
sition, would  consist  exclusively  of  tricalcic  silicate,  and  would  be  there- 
fore composed  entirely  of  lime  and  silica  in  the  following  proportions: 

Lime  (CaO) 73.6 

Silica  (SiO2) 26.4 

Such  an  ideal  cement,  however,  cannot  be  manufactured  under 
present  commercial  conditions,  for  the  heat  required  to  clinker  such  a 
mixture  cannot  be  attained  in  any  working  kiln.  The  oxyhydrogen 
blowpipe  and  the  electrical  furnace  will  give  clinker  of  this  composition; 
but  a  pure  lime-silica  Portland  is  not  possible  under  present  conditions 
as  to  burning  and  grinding  on  a  commercial  scale. 

In  order  to  prepare  Portland  cement  in  actual  practice,  therefore, 
it  is  necessary  that  some  other  ingredient  or  ingredients  should  be  pres- 
ent to  serve  as  a  flux  in  aiding  the  combination  of  the  lime  and  silica, 
and  such  aid  is  afforded  by  the  presence  of  alumina  and  iron  oxide. 

Alumina  (A^Os)  and  iron  oxide  (Fe203)  when  present  in  notice- 
able percentages  serve  to  reduce  the  temperature  at  which  combina- 
tion of  the  lime  and  silica  (to  form  3CaO,Si02)  takes  place;  and  this 
clinkering  temperature  becomes  further  and  further  lowered  as  the 


384  CEMENTS,  LIMES,  AND   PLASTERS. 

percentages  of  alumina  and  iron  are  increased.  The  strength  and  value 
of  the  product,  however,  also  decrease  as  the  alumina  and  iron  increase; 
so  that  in  actual  practice  it  is  necessary  to  strike  a  balance  between 
the  advantage  of  ow  clinkering  temperature  and  the  disadvantage  of 
weak  cement,  and  to  thus  determine  how  much  alumina  and  iron  should 
be  used  in  the  mixture.  Tnis  point  ^will  be  further  discussed  on  later 
pages. 

It  is  generally  considered  that  whatever  alumina  is  present  in  the 
cement  is  combined  with  part  of  the  lime  to  form  the  compound 
2CaO,Al2O3, — dicalcic  aluminate.  It  is  also  held  by  some,  but  this  fact 
is  somewhat  less  firmly  established  than  the  last,  that  the  iron  present 
is  combined  with  the  lime  to  form  the  compound  2CaO  Fe2O3.  This 
question  of  the  action  of  the  iron  will  be  later  referred  to.  For  the 
purposes  of  the  present  chapter  it  will  be  sufficient  to  say  that  in  the 
relatively  small  percentages  in  which  iron  occurs  in  Portland  cement 
it  may  for  convenience  be  considered  as  approximately  equivalent  to 
alumina  in  its  action. 

Influence  of  Normal  Constituents  on  the  Cement. 

Lime,  silica,  alumina,  iron  oxide,  magnesia,  sulphur,  and  alkalies 
may  be  regarded  as  being  normal  constituents  of  any  Portland-cement 
mixture.  The  three  first  named  are  necessary  ingredients,  while  the 
last  two,  though  undesirable,  are  rarely  entirely  absent  from  the  raw 
materials  used.  The  influence  exerted  by  greater  or  lesser  propor- 
tions of  these  seven  constituents  on  the  properties  of  both  mixture 
and  finished  cement  will  be  discussed  in  the  present  chapter. 

Maximum  lime  content  of  mixture. — On  pages  392-393  New- 
berry's  method  of  proportioning  cement  mixtures  will  be  described 
and  exemplified.  It  should  be  borne  in  mind,  however,  that  the  New- 
berry  formula  there  quoted  will,  if  followed,  give  the  maximum  lime 
content  that  the  mixture  could  bear,  providing  that  the  grinding,  mixing, 
and  calcination  were  performed  with  absolute  perfection.  As  a  matter 
of  fact,  however,  the  lime  content  of  the  mixture  should  never  be  car- 
ried quite  as  high  as  this  formula  would  indicate,  for  in  actual  practice 
the  mixing,  grinding,  and  calcination  are  never  theoretically  perfect, 
and  in  consequence  of  a  perfect  combination  of  all  the  lime  with  all 
the  silica  and  alumina  cannot  be  attained.  There  will  always  remain 
a  certain  amount  of  uncombined  material.  If  therefore,  the  lime  in 
the  mixture  is  carried  as  high  as  is  theoretically  allowable,  a  certain 
amount  of  free  lime  will  occur  in  the  cement.  If,  on  the  other  hand, 
the  mixture  carries  less  than  its  proper  theoretical  percentage  of  lime, 


CALCULATION  AND  CONTROL  OF  THE  MIX.  385 

i 

the  cement  will,  of  course,  contain  some  uncombined  silica  or  alumina. 
A  choice  must  be  made,  therefore,  between  the  possibilities  of  having 
free  lime  in  the  product  and  having  uncombined  clayey  matter.  This 
choice  is  simple,  for  the  effects  on  the  value  of  the  cement  of  these 
two  possibilities  are  very  different.  Free  lime  is  positively  dangerous 
to  the  cement,  while  free  clayey  materials  are  merely  inert,  their  only 
effect  being  to  lower  the  tensile  strength  of  the  product.  For  this  reason, 
since  in  practice  it  is  necessary  to  choose  between  the  two  contingencies 
(free  lime  vs.  free  silica  and  alumina),  the  lime  content  of  the  mixture 
is  always  carried  lower  than  theoretical  considerations  demand. 

It  is  to  be  further  noted  in  this  connection  that  the  lime  content 
of  Portland  cements  relatively  high  in  silica  may  be  carried  higher 
than  in  the  case  of  the  more  aluminous  Portlands.  In  discussing  the 
constitution  of  Portland  cement  in  preceding  paragraphs  it  was  stated 
that  though  lime  combines  with  both  silica  and  alumina,  the  combin- 
ing proportions  are  very  different  in  the  two  cases.  With  silica,  lime 
forms  the  tricalcic  .silicate,  whose  percentage  composition  is  lime  73.6 
per  cent,  silica  26.4  per  cent;  the  lime  and  silica  are  therefore  com- 
bined in  the  proportion  of  lime  2.8  to  silica  1.  With  alumina,  lime 
forms  a  less  basic  compound,  the  dicalcic  aluminate.  The  percentage 
composition  of  this  compound  is  lime  52.3  per  cent,  alumina  47.7  per 
cent,  corresponding  about  to  the  proportion  lime  1.1  to  alumina  1. 
It  is  evident,  therefore,  that  a  mixture  containing  20  per  cent  silica 
and  5  per  cent  alumina  can  safely  carry  more  lime  than  one  contain- 
ing 15  per  cent  silica  and  10  per  cent  alumina. 

Since  the  combination  of  lime,  silica,  and  alumina  becomes  more  thor- 
ough in  proportion  as  the  mixing,  grinding,  and  burning  are  better  done, 
higher  lime  contents  can  be  carried  by  carefully  prepared  mixtures 
than  by  careless  or  coarsely  ground  mixtures ;  and  in  rotary-kiln  plants 
lime  may  be  carried  higher  than  in  those  using  dome  kilns. 

Up  to  the  limit  of  safety  every  increase  in  the  percentage  of  lime 
in  the  mixture  will  cause,  other  things  being  equal,  an  increase  in  the 
strength  of  the  cement.  This  fact  is  taken  advantage  of,  particularly 
when  a  new  brand  is  being  placed  on  the  market.  The  usual  method 
of  procedure  at  such  a  time  is  to  carry  the  lime  very  high,  burn  very 
hard,  and  pulverize  very  fine.  This  makes  a  costly  but  high-testing 
cement.  As  soon  as  the  brand  has  become  well  established,  the  lime 
content  can  be  dropped  to  reasonable  working  limits. 

Minimum  lime  content  of  mixture. — The  maximum  lime  content 
of  the  mixture  is  fixed  by  the  considerations  set  forth  in  the  preceding 
paragraphs.  The  minimum  lime  content,  however,  will  also  require 


386  CEMENTS,  LIME8,  AND   PLASTERS. 

some  consideration.  Low  lime  will  invariably  mean  low-testing  cements, 
and  in  the  present  state  of  the  industry,  low-testing  cements  are  not 
easily  marketed.  A  low-lime  content  is  also  the  cause,  in  part,  of  the 
"dusting"  of  clinker  in  the  vertical  kiln.  Le  Chatelier  found  that  the 
dicalcic  silicate  (2CaO,SiO2)  possesses  the  property  of  spontaneously 
disintegrating  on  cooling.  If  the  lim^  content  of  the  mixture  be  carried 
too  low,  therefore,  the  clinker  will  fall  to  dust  in  the  kiln,  owing  to  the 
production  of  this  unstable  dicalcic  silicate. 

Magnesia.— The  question  as  to  the  percentage,,  of  magnesia  allow- 
able in  a  Portland  cement  has  given  rise  to  serious  controversy  for 
many  years.  In  Europe  the  tendency  has  been  to  keep  it  below  3  per 
cent;  but  in  this  country,  largely  because  of  the  results  attained  by 
Lehigh  Valley  cements  above  this  limit,  4  or  5  per  cent  has  been  con- 
sidered the  allowable  maximum.  All  this  discussion  was  carried  on 
under  the  idea  that  magnesia  was  either  inert  or  positively  harmful  in  a 
Portland  cement. 

Recent  experiments  by  Prof.  Newberry,  however,  have  proven  that 
an  entirely  satisfactory  cement  can  be  made  carrying  as  high  as  10 
per  cent  of  magnesia,  if  due  care  be  given  to  the  mixing  and  burning. 
This  might  have  been  expected,  both  on  theoretical  grounds  and  be- 
cause of  the  evidently  active  nature  of  magnesia  in  even  the  highest- 
burned  natural  cements,  as  pointed  out  on  pages  198-200.  At  present 
it  seems  safe  to  say  that  magnesia  can  be  considered  equivalent  to  lime 
in  its  action,  if  due  allowance  be  made  for  the  difference  in  their  com- 
bining weights.  It  is  therefore  theoretically  possible  to  prepare  a  series 
of  lime-magnesia  Portlands,  parallel  to  our  present  lime  Portlands; 
and  it  is  probable  enough  that  in  a  few  years  some  move  will  be  made 
in  this  direction.  But  it  must  be  borne  in  mind  that  a  lime-magnesia 
Portland  will  probably  differ  in  important  respects  from  our  present  lime 
Portlands,  and  that  it  will  therefore  be  inadvisable  to  group  the  two 
types  of  cement  under  the  same  general  name.  For  this  reason,  in 
the  present  volume,  the  term  Portland  has  been  restricted  by  defini- 
tion to  apply  only  to  cements  carrying  less  than  5  per  cent  of  magnesia 
(MgO). 

Silica. — It  is  commonly  considered  that  the  ultimate  strength  of 
the  cement  depends  in  large  part  upon  the  amount  of  calcium  trisilicate 
it  contains.  Within  certain  limits,  therefore,  any  increase  in  the  per- 
centage of  silica  in  the  mixture  will  increase  the  strength  of  the  cement. 
On  the  other  hand,  an  increase  in  silica  will  *  usually  imply  a  decrease 
in  alumina  and  iron  oxide,  and  this  in  turn  will  cause  the  cement  to 
be  slow-setting  (which  is  an  advantage),  but  hard  to  clinker. 


CALCULATION  AND  CONTROL  OF  THE  MIX.  387 

Alumina. — To  the  calcium  aluminate  of  a  cement  are  ascribed  the 
initial  setting  properties.  Decrease  in  the  alumina,  therefore,  tends  to 
make  the  cement  slower  setting,  while  high  alumina  affects  it  in  the 
opposite  way.  Though  it  is  advisable  to  carry  the  alumina  as  low  as 
possible,  so  as  to  secure  slowness  of  set  and  greater  ultimate  strength, 
it  is  impossible  to  carry  it  below  a  certain  minimum,  for  alumina  aids 
greatly  in  securing  a  low  clinkering  temperature,  and  a  cement  very 
low  in  alumina  will  clinker  only  with  great  difficulty.  Too  much  alumina, 
on  the  other  hand,  will  give  a  very  fusible  and  sticky  clinker,  liable 
to  ball  in  the  kiln. 

Le  Chatelier  considers  that  the  aluminous  compounds  present  in 
Portland  cement  are  the  direct  cause  of  its  destruction  by  sea-water. 
His  theory  to  account  for  this  disintegration  is  as  follows:  Free  lime, 
liberated  during  the  hardening  of  the  cement,  reacts  with  the  mag- 
nesium sulphate  always  present  in  sea-water,  to  form  calcium  sulphate. 
This  in  turn  reacts  with  the  calcium  aluminate  of  the  cement  to  form 
a  sulphaluminate  of  lime,  which  swells  considerably  on  hydration  and 
thus  disintegrates  the  cement  mass.  The  extent  of  the  disintegration 
varies  directly  with  the  percentage  of  alumina  present  in  the  cement. 
Cements  containing  1  or  2  per  cent  of  alumina  are,  for  example,  prac- 
tically unaffected  by  sea-water,  while  in  cements  containing  as  high 
as  7  or  8  per  cent  of  alumina  the  swelling  and  consequent  disintegration 
are  very  rapid. 

If  the  alumina  of  a  cement  be  replaced  by  an  oxide  not  reacting 
with  calcium  sulphate,  the  stability  of  the  cement  in  sea-water  is  greatly 
improved.  Le  Chatelier  has  demonstrated  this  by  preparing  cements 
in  which  the  alumina  was  replaced  by  oxides  of  iron,  chromium,  cobalt, 
etc.  All  of  these  were  more  resistant  than  an  alumina  cement  to  the 
disintegrating  effect  of  lime  sulphate.  The  best  effects  were  obtained 
when  iron  oxide  was  used,  a  cement  corresponding  in  composition  to 
5Si02,Fe2O3,17CaO  being  found  to  be  not  only  stable  in  presence  of 
sea-water  but  to  possess  excellent  mechanical  properties. 

DevaPs  researches  *  on  the  effect  of  direct  addition  of  calcium  sul- 
phate to  various  cements  confirm  the  above  theory.  Each  of  the  finely 
ground  cements  tested  was  completely  hydrated  by  mixing  with  50 
per  cent  of  water  and  storing  the  mixture  under  water  for  three  months 
out  of  contact  with  carbon  dioxide.  The  mass  was  then  dried,  reground, 
mixed  with  half  its  weight  of  calcium  sulphate  and  33  per  cent  of  water, 
and  made  up  into  rods  which  were  kept  moist  and  protected  from  car- 

*  Abstract  in  Jour.  Soc.  Chem.  Industry,  vol.  21,  pp.  971-972. 


388 


CEMENTS,  LIMES,  AND   PLASTERS. 


bon  dioxide  by  storage  on  moistened  filter-paper  under  a  glass  bell. 
At  the  end  of  three  weeks  the  increase  in  length  of  the  rods  was  measured 
with  the  following  results. 

TABLE  168. 
EFFECT  OF  ALUMINA. 


Type  of  Cement. 

Per  Cent 

of  Alumina 
in  Cement. 

Per  Cent  of 
Elongation 
of  the  Rods. 

Slag  cement  (Vitrv)  

15.5 

*      27 

"        (Champignolles)  
Grappier  cement  (Besses)       .  .  . 

14.5 

7  5 

16 
14 

Portland  cement  

6  2 

12 

Hydraulic  lime  (Besses)  

4  7 

4 

It  will  be  noted  that  the  percentage  of  elongation  of  the  rods  varied 
directly  with  the  percentage  of  alumina  in  the  cements  tested,  proving 
conclusively  that  the  swelling  was  due  to  the  action  of  the  calcium  sulph- 
aluminate  formed  during  the  operation. 

Iron  oxide. — Iron  oxide,  though  usually  so  low  as  to  be  negligible 
in  a  Portland  cement,  occasionally  is  present  in  considerable  percent- 
ages (4  to  6  per  cent).  When  this  is  the  case,  it  can  only  be  con- 
sidered as  equivalent  to  alumina  in  its  action,  allowing,  of  course,  for 
their  difference  in  combining  weights.  This  conclusion  is  borne  out 
by  the"  fact  that  Portland  cements  practically  free  from  alumina  have 
been  made,  containing  lime,  silica,  and  iron  oxide  only. 

Sulphur. — Sulphur,  when  present  in  a  cement  mixture,  may  occur 
either  as  a  sulphide  or  sulphate.  In  the  former  condition  it  is  usually 
due  to  the  occurrence  of  pyrite  (iron  disulphide,  FeS2)  either  in  the  lime- 
stone or  in  the  clay.  When  present  as  a  sulphate,  it  is  usually  in  the 
form  of  gypsum  (hydrous  calcium  sulphate,  CaS04  +  2H20). 

In  the  rotary  kiln,  which  usually  has  an  abundantly  oxidizing  flame, 
it  is  probable  that  any  calcium  sulphate  present  is  dissociated  (CaSC>4 
=^CaO  +  S03)  and  the  sulphur  trioxide  carried  off,  as  this  dissociation 
occurs  at  a  temperature  much  lower  than  that  reached  in  clinkering. 
If  the  flame  is  not  sufficiently  oxidizing,  however,  and  because  of  imper- 
fect draft  this  condition  is  likely  to  occur  in  vertical  kilns,  any  lime 
sulphate  present  will  be  reduced  to  the  sulphide  form. 

Alkalies. — Small  percentages  of  soda  and  potash  are  usually  present 
in  the  mixture,  due  mostly  to  their  presence  in  the  clay  or  shale.  Alka- 
lies have  been  regarded  as  detrimental,  as  inert,  and  as  beneficial;  and 
much  discussion  has  taken  place  on  the  subject,  based  mostly  on  purely 
theoretical  considerations. 


CALCULATION  AND  CONTROL  OF  THE  MIX.  389 

In  experimenting  with  various  methods  for  analyzing  Portland 
cement,  Hillebrand  encountered  the  question  of  loss  of  alkalies  during 
burning,  which  he  discusses  *  as  follows: 

"Long  before  the  last  of  the  sulphur  trioxide  is  expelled  alkali  begins 
to  volatilize,  and  it  is  easy  to  remove  all  or  nearly  all  in  this  manner. 
The  alkali  is  volatilized  as  oxide  and  may  be  collected  in  quantity  on 
the  under  side  of  the  crucible  lid.  At  the  intense  temperature  of  the 
rotary-kiln  furnace  this  action  must  play  an  important  part,  and  to  it  is 
to  be  attributed  the  great  loss  of  alkali  noted  by  me  in  the  cement  of 
1901,  as  compared  with  the  raw  mix  from  which  it  was  made,  an  obser- 
vation which  is  repeated  in  the  present  case  and  must  be  general  in 
cement-burning . ' ' 

Phosphorus. — Phosphorus,  combined  with  lime  in  the  form  of  lime 
phosphate,  frequently  occurs  in  notable  percentages  in  limestones,  par- 
ticularly in  the  soft,  chalky  limestones  and  " marls"  of  the  Southern 
States.  In  analyses  this  will  be  reported  as  phosphoric  acid  or  phos- 
phorus pent  oxide  (^2^5),  when  it  is  determined  at  all.  Few  com- 
mercial analysts,  however,  would  look  for  it  in  a  cement  material,  and 
it  is  therefore  rarely  reported. 

Late  in  1903  samples  of  a  "marl"  and  clay  from  a  Southern  State 
were  sent  to  a  leading  testing  laboratory  to  obtain  a  decision  on  their 
value  as  cement  materials.  Three  different  burnings  of  cement  were 
made  from  the  raw  materials  in  various  mixtures,  and  the  resulting 
cements  gave  the  tests  shown  in  Table  172,  below.  In  addition  to  these 
generally  poor  results  the  chemists  reported  that  the  cement,  for  a 
week  or  so  after  setting,  was  so  soft  that  it  could  be  readity  rubbed 
off  by  the  hand.  The  various  defects  in  the  cements  were  ascribed 
by  the  laboratory  experts  to  the  presence  in  the  marls  of  notable  per- 
centages of  phosphoric  acid.  The  matter  was  referred  to  me  by  the 
Southern  company,  and  at  my  request  Prof.  Clifford  Richardson  exam- 
ined microscopically  several  thin  sections  of  the  clinker  which  had 
been  made  in  the  laboratory  tests.  He  reported  that  the  raw  mix  had 
been  very  coarsely  ground  and  the  clinker  underburned. 

The  raw  materials,  as  analyzed  at  the  laboratory,  showed  the  results 
given  in  Table  169.  Two  samples  of  marl  were  tested  and  one  of  clay. 

Of  the  three  samples  of  cement  made  up  from  these  materials  and 
tested  as  below  (Table  170),  Cements  A  and  B  were  made  by  mixing 
Marl  1  and  clay  in  different  proportions,  while  Cement  C  was  made 
from  a  mixture  of  Marl  2  and  the  same  clay. 


*Journ.  Amer.  Chem.  Soc.,  vol.  25,  p.  1200.     1903. 


390 


CEMENTS,  LIMES,  AND  PLASTERS. 


TABLE  169. 
ANALYSES  OF  RAW  MATERIALS  CONTAINING  PHOSPHORIC  ACID. 


Marl  1. 

Marl  2. 

Clay. 

Silica  (SiO2) 

9.02 

3.88* 

1    10 

9.99 
2.05 
1.20 
45.82 
0.80 
37.99 

1.23 
*. 

38.96 
22.60 
5.82 
16.44 
0.32 
16.02 

Alumina  (A12O3) 

Lime  (CaO)             : 

45.78 
0.75 

38.87 

Magnesia  (MgO)       

Volatile  (CO2,  etc  )  

Phosphorus  pentoxide  (P2O5) 

*  Including  about  1  per  cent 

TABLE  170. 
TESTS  OF  CEMENTS  CONTAINING  PHOSPHORIC  ACID. 


Cement  A. 

Cement  B. 

Cement  C. 

Composition  :  Silica  (SiO2)  

22  20 

21    87 

24  26 

Alumina  (A12O3) 

10  23  f 

6  84 

7  97 

Iron  oxide  (Fe2O3) 

2  64 

2  60 

3  22 

Lime  (CaO) 

63  83 

64  85 

58  74 

Magnesia  (MgO) 

1  11 

1  30 

1  21 

Phosphorus  pentoxide  (P2OB).. 

See  A12O3 

2.50 

3.82 

Per  cent  plaster  added  

U% 

2% 

14% 

Fineness  :  Passing    50-mesh  sieve  

100.0 

100.0 

100  0 

100-    "      •  "    .  .  

96.3 

98.8 

94.0 

<  <        200-  '  "        " 

76  0 

80  0 

71  0 

Setting  time  •    initial                  

1  hr    10  min 

1  hr   25  min 

12  min 

final                   

5  hrs    0  min 

7  hrs  10  min 

18  min 

Tensile  strength:  neat,    1  day  

56  Ibs. 

49  Ibs. 

173  Ibs 

1  '        7  days 

510    " 

531     " 

213    " 

"      28     " 

754    " 

754    " 

340    " 

1-3       7     " 

180    " 

166    " 

72    " 

'  '      28     "                 .... 

327    " 

280    " 

80    " 

t  Including  about  2  per  cent  P2Os- 

Influence  of  intentionally  added  fluxes. — At  a  number  of  plants 
working  on  materials  or  mixtures  which  are  naturally  difficult  to  fuse, 
experiments  have  been  made  on  the  reduction  of  the  clinkering  tem- 
perature by  the  addition  of  fluxing  materials.  Experiments  of  this 
kind  are  usually  taken  up  in  the  early  stages  of  the  manufacturer's  experi- 
ence. They  rarely  outlast  the  first  year  of  actual  practice,  because 
he  then  begins  to  realize  that  it  is  difficult  enough  to  secure  a  homo- 
geneous and  uniform  mixture  of  two  ingredients  without  going  to  the 
extra  trouble  of  adding  a  third  material.  Occasionally,  however,  the 


CALCULATION  AND  CONTROL  OF  THE  MIX.  391 

fluxing  mania  persists,  and  in  a  few  rare  cases  it  may  be  entirely  justi- 
fiable. 

Fluorspar,  sodium  carbonate,  and  other  alkali  salts  are  the  favorite 
materials  for  use  as  fluxes.  It  is  certainly  true  that  the  addition  of 
a  very  small  percentage  of  some  of  these  salts  will  decrease  materially 
the  difficulty  of  clinkering  a  cement  mixture.  Any  other  effect  they 
may  have  on  the  cement,  however,  is  either  negatively  or  positively 
harmful;  and  in  all  cases  their  use  can  be  avoided  and  equally  good 
burning  results  obtained  by  a  slightly  increased  fineness  of  grinding 
of  the  raw  materials. 

The  direct  addition  of  iron  oxide  as  a  flux,  a  practice  which  is  followed 
by  at  least  one  large  American  plant,  is  somewhat  different  from  the 
use  of  fluorspar  or  alkalies.  The  iron  oxide  decreases  the  clinkering 
temperature  very  materially  and  gives  a  slower  setting  product  than 
would  an  equal  percentage  of  alumina.  Adding  it  separately  to  the 
mixture  is,  however,  a  difficult  matter  to  arrange.  The  more  natural 
course  to  pursue  would  be  to  look  for  another  source  of  clay  supply, 
attempting  to  find  a  clay  sufficiently  high  in  iron  to  obviate  the  necessity 
for  adding  iron  oxide  separately. 

Calculating  Mixtures  of  Untried  Materials. 

When  absolutely  untried  raw  materials  are  being  tested  for  the 
first  time,  the  experimental  mixture  must  be  solely  on  the  basis  of  their 
analyses,  as  developed  in  the  formula  given  below  or  in  some  similar 
device.  After  the  plant  has  once  started,  more  empirical  methods  of 
calculating  the  mix  are  used,  as  set  forth  in  a  later  section  (pp.  393-394). 

Cementation  Index. — Recalling  the  discussion  on  page  383  of  the 
theoretical  constitution  of  Portland  cement,  it  is  evident  that  the  ideal 
cement  (and  therefore  the  cement  mixture)  should  contain  its  various 
ingredients  in  such  percentages  that  the  following  compounds  can  be 
formed:  3CaO,  Si02,  2CaO.Al2O3,  2CaO.Fe203,  3MgO.SiO2,  2MgO.Al2O3, 
2MgO.Fe2O3.  These  conditions  are  satisfied  if  the  formula  below,  called 
for  convenience  the  Cementation  Index,  gives  a  value  of  unity.  In 
this  formula  the  chemical  equivalents  above  noted  have  been  changed 
into  percentages. 

(2. 8  X  per  cent  age  silica  (Si02)  )  +  (1.1  X  percentage  alumina,  A1203) 

+  (.7  X  percentage  iron  oxide,  Fe2O3) 
(Percentage  lime,  CaO)  +  (l. 4  X  percentage  magnesia,  MgO) 

When  the  value  given  by  this  formula  falls  below  1.0  the  cement 
must  necessarily  contain  free  lime  or  free  magnesia;  when  it  rises 
above  1.0,  the  cement  must  necessarily  be  lower  in  lime  than  is  theo- 


392  CEMENTS,  LIMES,  AND   PLASTERS. 

retically  possible.  The  aim  of  the  manufacturer,  therefore,  is  to  get 
a  cement  whose  Cementation  Index  is  on  the  safe  side  (i.e.,  over  1.0), 
•but  not  too  much  so. 

Use  of  the  formula  in  proportioning  mixtures. — The  use  cf  a  similar 
formula  in  calculating  mixtures  to  be  made  from  untried  materials  has 
been  well  described  by  Prof;  Newberry.  The  discussion  here  presented 
differs  from  his  only  in  the  fact  that  -the  magnesia  and  iron  are  allowed 
for,  a  correction  which  now  seems  necessary. 

Following  this  rule,  the  various  steps  in  the  proportioning  of  a  cement 
mixture  are  given  below  in  sufficient  detail  to  be*' readily  followed. 

OPERATION  1.  Multiply  the  percentage  of  silica  in  the  clayey  ma- 
terial by  2.8,  the  percentage  of  alumina  by  1.1,  and  the  percentage 
of  iron  oxide  by  0.7;  add  the  products;  subtract  from  the  sum  thus 
obtained  the  percentage  of  lime  oxide  in  the  clayey  material  plus  1.4 
times  the  percentage  of  magnesia  and  call  the  result  n. 

OPERATION  2.  Multiply  the  percentage  of  silica  in  the  calcareous 
material  by  2.8,  the  percentage  of  alumina  by  1.1,  and  the  percentage 
of  iron  oxide  by  0.7;  add  the  products  and  subtract  the  sum  from  the 
percentage  of  lime  oxide  plus  1.4  times  the  percentage  of  magnesia 
in  the  calcareous  material,  calling  the  result  m. 

OPERATION  3.  Divide  n  by  m.  The  quotient  will  be  the  number  of 
parts  of  calcareous  material  required  for  one  part  of  clayey  material. 

Example.  Assuming  that  materials  of  the  following  composition  are  in 
use  the  operation  would  be  as  follows: 

Clay.  Limestone. 

Silica  (SiO2) 62.2  2.4 

Alumina  (A12O3) 16.1  2.0 

Iron  oxide  (Fe2O3) 4.2  0.3 

Lime  (CaO) 1.6  50.2 

Magnesia  (MgO) 1.2  1.5 

Sulphur  trioxide  (SO3) 1.7  0.6 

Alkalies  (K2O,Na2O) 0.8  0.4 

Water,  carbon  dioxide,  etc 12.2  42 .6 

Operation  (1).  Clay. 

Silica  X2. 8  =  62. 2X2. 8  =  174. 16 

Alumina      Xl.l  =  16.1X1.1  =    17.71 
Iron  oxide  X0.7=   4.2X0.7=     2.94 


194.81 

Lime  Xl.0=    1.6X1.0=      1.6 

Magnesia     XL 4=    1.2X1.4=      1.68 


3.28 
194. 81-3. 28  =  191. 53  =  n. 


CALCULATION  AND  CONTROL  OF  THE  MIX.  393 

Operation  (2).  Limestone. 

Silica  X2.8  =  2.4   X2.8  =  6.72 

Alumina       Xl.l  =   2.0X1.1=  2.20 

Iron  oxide  X0.7=   0.3X0.7=  0.21 


9.13 

Lime  Xl.O  =  50.2Xl  .0  =  «50.2 

Magnesia     Xl.4=    1.5X1.4=     2.10 


52.30 
52. 30-9. 13  =  43. 17  =m. 

Operation  (3). 

-j^- =  4  44=  parts  of  limestone  to  be  used  for  each  part  of  clay,  by  weight. 

It  must  be  recollected  that  the  value  given  by  the  above  formula 
represents  the  highest  amount  of  lime  theoretically  possible  under 
the  best  possible  conditions  of  fine  grinding  and  thorough  burning. 
Even  in  the  best-run  plants  these  conditions  cannot  be  attained  in 
practice,  and  in  a  trial  run  either  in  a  test  kiln  or  in  an  actual  plant 
it  is  foolish  to  attempt  to  reach  this  limit.  The  limestone  shown  by 
the  formula  should  therefore  be  reduced  in  order  to  get  safe  results. 
A  reduction  of  10  per  cent  will  probably  be  satisfactory.  In  the  ex- 
ample given  above  this  would  work  out  as  follows: 

4.44=  parts  limestone  (to  1  of  clay)  allowed  by  formula 

0.44  =  10%  reduction  for  safety 

4.00  =  parts  limestone  (to  1  of  clay)  to  be  actually  used 

Calculating  Mixtures  in  Current  Work. 

After  a  plant  has  once  gotten  into  good  working  order,  and  as  long 
as  the  same  raw  materials  are  in  use,  the  calculation  of  the  mix  becomes 
a  much  simpler  affair.  Two  general  methods  are  in  use: 

At  most  plants  the  percentage  of  carbonates  in  the  mix  is  made 
the  criterion.  If  good  results  have  been  attained  with  mixtures  carry- 
ing 78  to  80  per  cent  total  carbonates  (CaCOs  +  MgCOs),  the  aim  of 
the  chemist  is  simply  to  keep  the  mix  within  the'se  limits.  The  calcu- 
lation in  this  case  is  simply  a  matter  of  arithmetic  which  does  not  re- 
quire explanation.  The  other  method  is  to  keep  a  fixed  ratio  between 
the  total  insoluble  matter  and  the  total  carbonates.  This  ratio  will 
naturally  be  different  at  each  plant,  but  will  always  be  fairly  constant 
at  any  one  plant. 

In  a  well-known  and  admirably  managed  marl-plant  the  marl  is 
analyzed  after  being  pumped  into  tanks  at  the  mills,  and  the  clay  on 


394 


CEMENTS,  LIMES,  AND  PLASTERS. 


its  arrival  at  the  mill.     Four  determinations  are  made  on  each  sample 
of  marl  and  three  on  the  clay.     These  are: 
Marl.    1.  Percentage  of  water; 

2.  Weight  per  cubic  foot; 

3.  Percentage  of  insoluble  matter; 

4.  Percentage  of  carbonates. 
Clay.    1.  Percentage  of  water;  ' 

2.  Percentage  of  insoluble  matter; 

3.  Percentage  of  carbonates. 

From  these  determinations  the  mix  is  proportioned  in  such  a  way 
that  the  ratio 

Carbonates 
Insoluble  matter 

shall  fall  within  certain  numerical  limits.  At  the  plant  in  question, 
which  runs  a  high-testing  cement  which  is  also  very  high  in  silica,  the 
above  formula  is  made  to  give  a  value  of  4.2.  In  the  majority  of  plants 
it  would  fall  about  3.0  to  3.4, 

Composition  of  mixture. — The  cement  mixture  ready  for  burning 
will  commonly  contain  from  74  to  77.5  per  cent  of  lime  carbonate,  or 
an  equivalent  proportion  of  lime  oxide.  Several  analyses  of  actual 
cement  mixtures  are  given  in  the  following  table.  The  ratio  of  silica 
to  alumina  plus  iron  for  ordinary  purposes  should  be  about  3:1,  for  the 
cement  becomes  quicker  setting  and  lower  in  ultimate  strength  as  the 
percentage  of  alumina  increases.  If  the  alumina  percentage  be  carried 
too  high,  moreover,  the  mixture  will  give  a  fusible,  sticky  clinker  when 
burned,  causing  trouble  in  the  kilns. 

TABLE  171. 
COMPOSITION  OF  ACTUAL,  MIXES. 


Silica  (SiO2)  

14.77 

12  85 

15.18 

11.8 

13.52 

V     ,    OK  f 

4.92 

Iron  oxide  (Fe2O3)    

1    -35l 

1  21 

>    6.42 

8.2 

6.56 

Lime  (CaO)           

43  03 

42  76 

42  97 

41.8 

42.07 

1.74 

1.02 

n.  d. 

0.8 

2.07 

Carbon  dioxide  (CO2) 

35  61 

34  71 

n  d 

n  d 

35  31 

Water 

n   d 

n   d 

n  d 

n  d. 

n  d 

Silica  (SiO2)     

13  46 

13  85 

12.62 

14.94 

12.  9? 

n  d  1 

f  2.66 

4.8c 

Iron  oxide  (Fe2O3)  

n  d  J 

7.20 

6.00 

t  1.10 

1.77 

Lime  (CaO) 

41  25 

41  40 

42  26 

42.34 

42.30 

Magnesia  (MgO)       .    .  i  .  .  . 

n   d 

n  d 

2  67 

2.21 

2.08 

Carbon  dioxide  (CO2)  

1  34  .  86 

[36.10 

35.68 

35.49 

Water 

36.42 

\n   d 

n  d 

n.  d. 

CALCULATION  AND   CONTROL  OF  THE  MIX.  395 

Methods  of  control. — The  chemist  having  determined  the  standard 
of  composition  which  he  wishes  to  maintain  in  the  mix,  several  different 
methods  of  maintaining  this  standard  are  possible.  Theoretically,  of 
course,  the  best  of  these  methods  is: 

(1)  Both  raw  materials  are  analyzed  as  they  arrive  at  the  mill; 
the  mix  is  made  according  to  these  analyses;    after  grinding  the  mix 
is  analyzed  as  a  check,  and  if  seriously  incorrect  is  corrected  by  the 
addition  of  the  necessary  ingredients.     This  method  is  actually  prac- 
ticed at  some  plants,  but  in  general  one  or  the  other  of  its  two  elements 
is  gradually  dropped  out,  so  that  most  plants  approach  one  of  the  two 
following  extremes  in  practice. 

(2)  The  raw  materials  are  analyzed,  either  by  borings  in  the  quarry 
or  by  an  arrival  at  the  mill,  and  the  mix  made  in  accordance  with  these 
analyses.     The  mix  may  be  analyzed  occasionally  as  a  check,  but  no 
serious  attempt  is  made  to  correct  it.     In  this  method  the  entire  reli- 
ance is  placed  on  the  analyses  of  the  raw  materials.     With  hard,  dry, 
raw  materials   varying  little  in  composition  the  plan  works  well.     In 
dealing  with  marls,  etc.,  the  third  plan  is  most  used. 

(3)  The  raw  materials  are  mixed  without  analysis  in  approximately 
correct  proportions,  according  to  previous  experience,  and  the  ground 
mix  is  analyzed  and  brought  up  to  proper  composition  (standardized)  by 
the  addition  of  whichever  raw  material  proves  to  be  deficient.     In  this 
method  the  correction  of  the  mix  is  a  regular  part  of  the  procedure.     For 
convenience  the  mix  is  usually  made  always  a  little  low  in  the  same  con- 
stituent, so  that  only  one  tank  or  bin  of  raw  material  needs  to  be  kept  on 
hand  for  standardizing.     The  following  blank  order  shows  how  this  is 
arranged  in  actual  practice  under  the  chemist's  direction: 

CLAY  ORDER. 


Date 

Tank  No requires  one  hopper 

of  clay  for  each 

inches  of  marl. 

Slurry  tank  No 


Changes  in  Composition  During  Manufacture. 

In  theory  the  cement  produced  should  correspond  in  composition 
to  the  mixture  from  which  it  is  made.     In  practice  it  is  found  that,  in 


396 


CEMENTS,  LIMES,  AND  PLASTERS. 


addition  to  the  expected  loss  of  water,  carbon  dioxide,  and  other  vola- 
tile components,  the  cement  has  suffered  other  changes  which  prevent 
it  from  having  the  exact  composition  calculated  from  the  mixture. 
During  the  process  of  burning,  the  clinker  has  taken  up  a  certain  amount 
of  material  from  the  fuel  ashes,  the  kiln  linings,  or  the  gases  produced 
in  the  kiln.  The  changes  in ,  composition  thus  caused  will  be  briefly 
discussed. 

The  change  in  composition  during  burning  is  almost  inevitably 
in  the  direction  of  raising  the  Cementation  Index  of  the  cement,  i.e., 
making  it  more  clayey.  This  is  due  to  the  fact  that  the  impurities 
picked  up  during  burning  are  all  of  a  clayey  character,  the  kiln  linings 
and  the  fuel  ash  being  predominantly  composed  of  silica  and  alumina. 
To  partly  counterbalance  these  additions  of  clayey  matter,  it  is  prob- 
able that  the  dust  blown  out  of  the  kiln  is  more  clayey  than  the  rest 
of  the  mix;  but  this  is  not  sufficient  in  amount  to  avail  much  against 
the  combined  influence  of  the  fuel  ash  and  the  kiln  lining.  Of  the  two 
factors  the  fuel  ash  is  by  far  the  most  important,  because  the  kiln  bricks 
are  pretty  steadily  covered  by  a  skin  of  clinker. 

The  variation  in  composition  of  the  ash  derived  from  different  types 
of  fuel  is  shown  by  the  following  analyses  made  by  Candlot.* 

TABLE  172. 
ANALYSES  OF  FUEL  ASH. 


Composition  of  Ash  from 

Anthracite. 

Gas  Coke. 

SiO2.  . 

40.10 
42.80 
4.70 
8.10 
0.90 
1.23 

29.30 
19.63 
14.64 
10.64 
2.70 
13.72 

ALO, 

FeA  ' 

CaO 

MgO   

SO3  

The  differences  between  the  calculated  and  actual  compositions  of 
a  cement  are  well  illustrated  by  the  example  given  below.  In  this  case 
a  marl  and  clay  of  determined  composition  were  mixed  in  a  known  ratio. 
The  composition  which  a  cement  made  from  this  mixture  should  show 
was  calculated  and  is  given  in  column  3,  while  the  composition  of  the 
cement  actually  resulting  is  given  in  column  4.  For  these  data  the 
writer  is  indebted  to  Prof.  S.  B.  Newberry;  who  carried  out  the  test 
in  question. 

*  Bonnami.  Fabrication  et  Controle  des  Chaux  Hydrauliques  et  des  Ciments, 
p.  58. 


CALCULATION  AND  CONTROL  OF  THE  MIX 


397 


TABLE  173. 
CHANGE  IN  COMPOSITION  DURING  BURNING. 


Raw  Materials. 

Finished  Product. 

Marl. 

Clay. 

Calculated. 

Actual 

Silica  (SiO2) 

1.16 
0.75 

0.75 
49.44 
2.04 
46.40 

57.08 
10.01 
5.37 
8.32 
5.22 
14.00 

22.20 
5.02 
2.85 
65.79 
4.06 
n.  d. 

0.974 

22.42 
5.68 
3.22 
62.24 
3.22 
n.  d 

1.068 

Alumina  (A12O3) 

Iron  oxide  (Fe2O3) 

Lime  (CaO)             

Magnesia  (MgO)     

Loss  (H2O,CO2,  etc  )  

Ceme1  tation  Index  

This  point  is  also  illustrated  by  the  following  analyses  of  raw  mix 
and  cement  from  the  Syracuse  plant ,  analyzed  by  Hillebrand.* 

TABLE  174. 
CEMENT  MIXTURE  AND  CEMENT,  SANDUSKY. 


Mix. 

Cement. 

Silica  (SiO2)  

13  51 

21  93 

Alumina  (Al  O3) 

3  32 

5  68 

Titanic  oxide  (TiO2) 

0  18 

0  31 

Iron  oxide  (Fe2O3) 

1  43 

2  35 

Lime  (CaO) 

40  84 

62  92 

Magnesia  (MgO) 

0  75 

1  10 

Potash  (K2O) 

0  79 

0  61 

Soda  (Na2O) 

0  22 

0  29 

Sulphur  (S) 

0  16 

0  09 

Sulphur  trioxide  (SO3).  .  .  . 
Carbon  dioxide  (CO2)  

1.43 
n   d 

1.53 
1  73 

Water  

4  20 

1  40 

Cementation  Index  

1.014 

1  075 

It  will  be  seen  that  in  both  these  experiments  the  Cementation  Index 
of  the  cement  has  been  raised  considerably  by  the  amount  of  silica  and 
alumina  taken  up  during  calcination. 


*  Jour.  Amer.  Chem.  Soc.,  vol.  25,  p.  1186.     1903. 


396 


CEMENTS,  LIMES,  AND   PLASTERS. 


addition  to  the  expected  loss  of  water,  carbon  dioxide,  and  other  vola- 
tile components,  the  cement  has  suffered  other  changes  which  prevent 
it  from  having  the  exact  composition  calculated  from  the  mixture. 
During  the  process  of  burning,  the  clinker  has  taken  up  a  certain  amount 
of  material  from  the  fuel  ashes,  the  kiln  linings,  or  the  gases  produced 
in  the  kiln.  The  changes  in .  composition  thus  caused  will  be  briefly 
discussed. 

The  change  in  composition  during  burning  is  almost  inevitably 
in  the  direction  of  raising  the  Cementation  Index  of  the  cement,  i.e., 
making  it  more  clayey.  This  is  due  to  the  fact  mat  the  impurities 
picked  up  during  burning  are  all  of  a  clayey  character,  the  kiln  linings 
and  the  fuel  ash  being  predominantly  composed  of  silica  and  alumina. 
To  partly  counterbalance  these  additions  of  clayey  matter,  it  is  prob- 
able that  the  dust  blown  out  of  the  kiln  is  more  clayey  than  the  rest 
of  the  mix;  but  this  is  not  sufficient  in  amount  to  avail  much  against 
the  combined  influence  of  the  fuel  ash  and  the  kiln  lining.  Of  the  two 
factors  the  fuel  ash  is  by  far  the  most  important,  because  the  kiln  bricks 
are  pretty  steadily  covered  by  a  skin  of  clinker. 

The  variation  in  composition  of  the  ash  derived  from  different  types 
of  fuel  is  shown  by  the  following  analyses  made  by  Candlot.* 

TABLE  172. 
ANALYSES  OF  FUEL  ASH. 


Composition  of  Ash  from 

Anthracite. 

Gas  Coke. 

SiO2 

40.10 
42.80 
4.70 
8.10 
0.90 
1.23 

29.30 
19.63 
14.64 
10.64 
2.70 
13.72 

ALO, 

FeLo* 

CaO    

MgO  

SO,.  . 

The  differences  between  the  calculated  and  actual  compositions  of 
a  cement  are  well  illustrated  by  the  example  given  below.  In  this  case 
a  marl  and  clay  of  determined  composition  were  mixed  in  a  known  ratio. 
The  composition  which  a  cement  made  from  this  mixture  should  show 
was  calculated  and  is  given  in  column  3,  while  the  composition  of  the 
cement  actually  resulting  is  given  in  column  4.  For  these  data  the 
writer  is  indebted  to  Prof.  S.  B.  Newberry.  who  carried  out  the  test 
in  question. 

*  Bonnami.  Fabrication  et  Controle  des  Chaux  Hydrauliques  et  des  Ciments, 
p.  58. 


CALCULATION  AND  CONTROL  OF  THE  MIX 


397 


TABLE  173. 
CHANGE  IN  COMPOSITION  DURING  BURNING. 


Raw  Materials. 

Finished  Product. 

Marl. 

Clay. 

Calculate!. 

Actual 

Silica  (SiO2) 

1.16 
0.75 
0.75 
49.44 
2.04 
46.40 

57.08 
10.01 
5.37 
8.32 
5  22 
14.00 

22.20 
5.02 
2.85 
65.79 
4.06 
n.  d. 

0.974 

22.42 
5.68 
3.22 
62.24 
3.22 
n.  d 

1.068 

Alumina  (A12O3)         .... 

Iron  oxide  (Fe2O3)    

Lime  (CaO)         

Magnesia  (MgO)  

Loss  (H2O,CO2,  etc.)  

Ceme1  tation  Index  

This  point  is  also  illustrated  by  the  following  analyses  of  raw  mix 
and  cement  from  the  Syracuse  plant,  analyzed  by  Hillebrand.* 

TABLE  174. 
CEMENT  MIXTURE  AND  CEMENT,  SANDUSKY. 


Mix. 

Cement. 

Silica  (SiO2)  

13.51 

21  93 

Alumina  (Al  O3) 

3  32 

5  68 

Titanic  oxide  (TiO2)  
Iron  oxide  (Fe2O3) 

0.18 
1  43 

0.31 
2  35 

Lime  (CaO)               ... 

40  84 

62  92 

Magnesia  (MgO)       .    .    . 

0  75 

1   10 

Potash  (K2O)            .    .    . 

0  79 

0  61 

Soda  (Na2O) 

0  22 

0  29 

Sulphur  (S)                    

0  16 

0  09 

Sulphur  trioxide  (SO3).  .  .  . 
Carbon  dioxide  (CO2)  

1.43 
n   d 

1.53 
1  73 

Water  

4  20 

1  40 

Cementation  Index 

1  014 

1  075 

It  will  be  seen  that  in  both  these  experiments  the  Cementation  Index 
of  the  cement  has  been  raised  considerably  by  the  amount  of  silica  and 
alumina  taken  up  during  calcination. 


*  Jour.  Amer.  Chem.  Soc.,  vol.  25,  p.  1186.     1903. 


400  CEMENTS,  LIMES,  AND   PLASTERS. 

30  per  cent  in  fresh  clays.  The  chemically  combined  water  will  depend 
largely  on  the  composition  of  the  clay;  and  may  vary  from  5  to  12  per 
cent.  The  hygroscopic  or  mechanically  held  water  of  clays  can  be 
driven  off  at  a  temperature  of  212°  F.;  while  the  chemically  combined 
water  is  lost  only  at  a  low  red  heat.  The  total  water,  therefore,  to  be 
driven  off  from  clays  may  range  frorn^G  to  42  per  cent,  depending  on 
the  weather,  the  drainage  of  the  clay-pit,  and  the  care  taken  in  pre- 
venting unnecessary  exposure  to  moisture  of  the  excavated  clay.  The 
average  total  amount  of  moisture  will  probably  be  about  15  per  cent. 

In  dealing  with  shales,  the  mechanically  held  water  will  rarely  rise 
above  10  per  cent,  and  can  commonly  be  kept  well  below  that  limit. 
An  additional  2  to  7  per  cent  of  water  will  be  carried  by  any  shale 
in  a  state  of  chemical  combination. 

At  a  few  plants  marl  is  used  with  clay  in  a  dry  process.  As 
noted  elsewhere  the  marls  as  excavated  carry  usually  about  50  per 
cent  of  water.  Marl  presents  a  more  difficult  problem  than  do  the  other 
raw  materials,  because  the  vegetable  matter  usually  present  in  marls 
is  extremely  retentive  of  water. 

It  will  be  seen,  therefore,  that  cement  materials  may  carry  from 
1  per  cent  to  50  per  cent  of  water  when  they  reach  the  mill.  The  aver- 
age throughout  the  country  would  probably  fall  close  to  5  per  cent 
if  the  marls  are  excluded.  In  a  dry  process  it  is  necessary  to  remove 
practically  all  of  this  water  before  commencing  the  grinding  of  the 
materials.  One  reason  for  this  is  that  fine  pulverizing  cannot  be  eco- 
nomically or  satisfactorily  accomplished  unless  absolutely  dry  material 
is  fed  to  the  grinding  machinery.  Another  reason,  which  is  one  of  con- 
venience rather  than  of  necessity,  is  that  the  presence  of  water  in  the 
raw  materials  complicates  the  control  of  the  cement  mixture. 

Methods  and  costs  of  drying. — The  type  of  dryer  used  at  most  cement- 
plants  is  a  cylinder  approximately  5  feet  in  diameter  and  40  feet  or  so 
in  length,  set  at  a  slight  inclination  to  the  horizontal  and  rotating  on 
bearings.  The  wet  raw  material  is  fed  in  at  the  upper  end  of  the  cylinder, 
and  it  moves  gradually  toward  the  lower  end,  under  the  influence  of 
gravity,  as  the  cylinder  revolves.  In  many  dryers  angle  irons  are  bolted 
to  the  interior  in  such  a  way  as  to  lift  and  drop  the  raw  material  alter- 
nately, thus  exposing  it  more  completely  to  the  action  of  the  heated 
gases  and  materially  assisting  in  the  drying  process.  The  dried  raw 
material  falls  from  the  lower  end  of  the  cylinder  into  an  elevator  boot 
and  is  then  carried  to  the  grinding-mills. 

The  drying-cylinder  is  heated  either  by  a  separate  furnace  or  by 
waste  gases  from  the  cement-kilns.  In  either  case  the  products  of 


PREPARING  THE  MIXTURE  FOR  THE  KILN. 


401 


402  CEMENTS,  LIMES,  AND   PLASTERS. 

combustion  are  introduced  into  the  cylinder  at  its  lower  end,  are  drawn 
through  it,  and  escape  up  a  stack  set  at  the  upper  end  of  the  dryer. 
The  dryer  above  described  is  the  simplest  and  is  most  commonly 
used.  For  handling  the  small  percentages  of  water  contained  in  most 
cement  materials  it  is  very  efficient,  but  for  dealing  with  high  percent- 
ages of  water,  such  as  are  encountered*  when  marl  is  to  be  usd  in  a  dry 
process,  it  seems  probable  that  double-heating  dryers  will  be  found 
more  economical. 

This  type  is  exemplified  by  the  Buggies-Coles .  dryer,  a  detailed 
description  of  which  is  given  in  the  section  on  slag  cements,  p.  649. 
In  this  dryer  a  double  cylinder  is  employed.  The  wet  raw  material 
is  fed  into  the  space  between  the  inner  and  outer  cylinders,  while  the 
heated  gases  pass  first  through  the  inner  cylinder  and  then,  in  a  reverse 
direction,  through  the  space  between  the  inner  and  outer  cylinders. 
This  double-heating  type  of  dryer  is  employed  in  almost  all  of  the  slag- 
cement  plants  in  the  United  States,  and  is  also  in  use  in  several  Port- 
land-cement plants. 

When  vertical  kilns  were  in  use,  drying-floors  and  drying-tunnels 
were  extensively  used,  but  at  present  they  can  be  found  only  in  a  few 
plants,  being  everywhere  else  supplanted  by  the  rotary  dryers. 

At  the  marl-plant  of  the  ill-fated  Hecla  Portland  Cement  Company, 
which  is  shown  in  Fig.  82,  rotary  kilns  were  actually  used  as  driers, 
because  of  the  extreme  difficulty  encountered  in  properly  drying  this 
material  in  a  drier  of  ordinary  type. 

In  the  Edison  plant  a  stationary  vertical  tower  drier  is  used  for 
the  cement  rock  and  limestone. 

The  Edison  stack  drier  shown  in  Fig.  83  is  described  as  follows 
in  a  recent  article  *  in  the  Iron  Age:  The  chimney  surmounting  this 
flue  is  used  only  when  starting  a  fire,  the  gases  of  combustion  ordi- 
narily passing  directly  to  the  dryer  stack  to  rise  through  the  falling 
stream  of  rock  and  thoroughly  dry  it.  The  baffle-plate  system  is  such 
that  the  fall  of  a  piece  of  rock  from  the  lowest  screen  to  the  bottom 
of  the  dryer  requires  26  seconds.  From  above  the  baffles  near  the 
top  of  the  stack  the  gases  are  drawn  out  by  an  80-inch  exhaust- 
fan,  driven  by  a  50-horse-power  motor,  and  are  passed  through  a 
dust-settling  chamber  on  their  wray  to  the  atmosphere.  A  12- 
inch  screw  conveyor  returns  the  collected  dust  to  the  bottom  of  the 
dryer  stack  and  replaces  it  in  the  system.  The  baffle-plates  of  the 


*  The  Iron  Age,  Dec.  24,  1903,  p.  5. 


PREPARING  THE  MIXTURE   FOR  THE  KILN. 


403 


upper  sections  of  the  stack  are  arranged  to 
slide  longitudinally  in  their  slots,  reciproca- 
ting motion  being  provided  by  a  motor- 
driven  system  of  rocker  arms  sliding  suc- 
cessive rows  of  plates  in  opposite  directions 
at  the  rate  of  20  cycles  per  minute.  By  this 
action  clogging  of  possibly  damp  rock  is  pre- 
vented until  it  has  fallen  far  enough  to  be 
dried  sufficiently  to  have  no  such  tendency. 
The  shear-pin  principle,  used  at  this  plant 
for  driving  the  crushing  rolls,  is  also  applied 
in  a  modified  form  to  the  baffle-shakers.  The 
rock-dryer  is  8X8  feet  in  plan  section,  40 
feet  high,  and  has  a  capacity  of  3000  tons 
per  day,  the  same  as  the  crusher  plant. 
The  performance  of  the  dryer  stack  is 
very  efficient;  the  fuel  consumption 
is  small,  the  percentage  of  moisture  in 
the  crushed  rock  is  reduced  from  3  or 
4  per  cent  to  within  1  per  cent,  and 
the  gases  leave  at  a  temperature  scarcely 
above  212°.  A  blower  equipment  is  pro- 
vided for  increasing  the  furnace  draft  when 
necessary. 

The  cost  of  drying  raw  materials  will 
depend  on  the  cost  of  fuels,  the  percentage  of 
water  present  in  the  wet  material,  and  the 
efficiency  of  the  dryer.  Dryers  are  usually 
arranged  and  located  so  as  to  require  little 
attention,  and  the  labor  costs  of  drying  are 
therefore  slight.  Even  under  the  most  un- 
favorable conditions  5  Ibs.  of  water  can 
be  expected  to  be  evaporated  for  each 
pound  of  coal  used,  while  a  good  dryer 
will  usually  evaporate  7  or  8  Ibs.  of  water 
per  pound  of  coal.  Marls  containing  much 
organic  matter  are  notably  more  reten- 
tive of  moisture  than  any  other  raw 
material,  and  a  marl-drying  proposition 

is   therefore  apt  to   be   expensive.      For   a 

f  „      ,         .    ,  .  . 

iull    description  of  a   most  elaborate   and 


10-C 


ia  83.—  Elevation  of  stack 
drier.  Edison  plant.  (En- 
gineering  NewsT) 


404  CEMENTS,  LIMES,  AND  PLASTERS. 

unsuccessful  installation  for  marl-drying,  reference  should  be  made  to 
the  paper  cited  below.* 

Grinding  and  Mixing. 

Part  at  least  of  the  reduction  is  usually  accomplished  before  the 
materials  are  dried,  but  for  convenience;  the  subjects  have  been  separated 
in  the  present  chapter. 

General  methods. — Usually  the  limestone  or  cement  rock  is  passed 
through  a  crusher  at  the  quarry  or  mill  before  being  sent  to  the  drier; 
and  occasionally  one  or  both  of  the  raw  materials  is  still  further  reduced 
before  grinding,  but  the  principal  part  of  the  grinding  process  always 
takes  place  after  the  material  has  been  dried. 

After  drying,  the  two  raw  materials  may  either  be  mixed  imme- 
diately or  each  may  be  separately  reduced  before  mixing.  Automatic 
mixers,  of  which  many  slightly  different  types  are  in  use,  give  a  mix- 
ture in  the  proportions  determined  upon  by  the  chemist. 

The  further  reduction  of  the  mixture  is  usually  carried  on  in  two 
stages,  the  material  being  ground  to,  say,  30-mesh  in  a  ball  mill,  kom- 
minuter,  Griffin  mill,  etc0,  and  finally  reduced  in  a  tube  mill.  At  a 
few  plants,  however,  single-stage  reduction  is  practiced  in  Griffin  or 
JBuntington  mills,  while  at  the  Edison  plant  at  Stewarts ville,  N.  J., 
the  reduction  is  accomplished  in  a  series  of  rolls. 

The  majority  of  plants  use  either  the  Griffin  mill  and  tube  mill  or 
the  ball  mill  and  tube  mill;  and  there  is  probably  little  difference 
in  the  total  cost  of  operating  these  two  combinations.  The  former 
combination  (Griffin  +  tube)  is  commonly  considered  to  require  less 
power,  but  more  repairs  than  the  latter;  but  even  this  can  hardly  be 
regarded  as  an  established  fact.  The  ball  mill  has  never  been  quite  as 
much  of  a  success  as  its  companion,  the  tube  mill,  and  has  been  replaced 
at  a  number  of  plants  by  the  kominuter. 

Plans  of  actual  plants. — Plans  of  several  actual  plants  have  been 
inserted  for  the  purpose  of  illustrating  the  brief  statement  made  above. 

The  plant  of  the  Lawrence  Cement  Company,  of  Siegfried,  Pa., 
published  by  courtesy  of  Messrs.  Lathbury  and  Spackman,  is  given 
in  Fig.  85.  The  materials  used  here  are  cement  rock  and  limestone. 
These  are  separately  crushed  in  Gates  crushers  and  dried  in  rotary 
driers,  after  which  they  are  mixed  and  reduced  in  Williams  mills  and 
tube  mills. 

*  Plant  and  buildings  of  the  Hecla  Portland  Cement  and  Coal  Co.  Engineering 
News,  vol.  51,  pp.  243-245.  1904. 


PREPARING  THE  MIXTURE   FOR  THE  KILN. 


405 


In  Fig.  84  the  raw  side  of  an  ideal  mill  is  presented,  showing  a  very 
compactly  installed  layout  of  kominuters  and  tube  mills  for  an  output 
of  3500  barrels  per  day. 


FIG.  84. — Installation  of  kominuters  and  tube  mills. 

The  plant  of  the  Hudson  P.  C.  Co.,  a  typical  modern  dry-process 
plant,  is  shown  in  Fig.  86,  reproduced  by  courtesy  of  Engineering  News. 


406 


CEMENTS,  LIMES,  AND  PLASTERS. 


In  the  article  *  accompanying  this  figure,  the  raw  side  of  the  mill  is 
described  as  follows: 

"Following  the  course  of  the  material  step  by  step,  it  will  be  seen 
that  the  loaded  cars  from  the  quarry  come  into  the  mill  at  the  east 
end  at  an  elevation  of  12  feet  above  the  crusher-room  floor,  which  is  itself 


FIG.  85.— Plan  of  plant,  Lawrence  Cement  Co.,  Siegfried,  Pa. 
(Lathbury  and  Spackman.) 

elevated  13J  feet  above  the  main  mill  floor,  and  that  they  dump  through 
the  track  onto  the  crusher-room  floor.  Flush  with  this  floor  are  the 
tops  of  three  rotary  crushers,  two  for  crushing  limestone  and  one  for 
crushing  shale.  The  two  limestone  crushers  are  run  by  a  45-H.P.  electric 
motor  and  the  shale  crusher  by  a  22-H.P.  electric  motor.  From  the 
crushers  the  stone  is  delivered,  shale  and  limestone  separately,  into  four 
rotary  driers,  each  of  which  is  operated  by  a  5-H.P.  electric  motor. 
From  the  driers  the  stone  passes  separately  to  the  ball  mills  for  the 
first  grinding.  These  ball  mills  are  of  the  Krupp  type,  and  there  are  five 
of  them,  each  operated  by  a  50-H.P.  electric  motor.  From  the  ball 

*  Engineering  News,  vol.  50,  pp.  70,  71.     July  23,  1903. 


PREPARING  THE  MIXTURE  FOR  THE  KILN. 


407 


CEMENTS,' LIMES,  AXD  PLASTERS. 


mills  the  shale  powder  is  delivered  to  a  set  of  two  bins  and  the  lime- 
stone powder  to  a  set  of  five  bins.  These  bins  are  so  constructed  as  to 
discharge  automatically  into  a  double  elevator,  whence  the  materials 
,are  discharged  into  a  double  hopper  over  a  tandem  automatic  weigh- 
ing-machine, which  weighs  out  the  proper  proportion  of  each  material. 
'The  two  products  are  then  mi^ed  thoroughly  by  being  conveyed  together 
by  elevator  E  and  conveyors  9^  and  9  -to  the  steel  bins  feeding  the  tube 
mills.  There  are  six  of  these  tube  mills  and  they  are  driven  in  groups 
by  a  75-H.P.  electric  motor. 

"  The  tube-mill  discharges  feed  onto  a  screw  conveyor  10,  thence  to 
the  elevator  EE,  and  thence  to  screw  conveyor  11,  which  discharges 
into  two  groups  of  stock  bins.  Screw  conveyors  13  running  under- 
neath these  bins  take  the  material  right  and  left  to  the  elevator  F, 
which  feeds  the  right  and  left  screw  conveyors  12  that  discharge  into 
the  kiln  feed  bins.  There  are  ten  of  these  bins  and  each  one  feeds  one 
rotary  kiln." 

Actual  Equipments  of  Dry-process  Plants. 

The  present-day  practice  in  dry-process  plants  is  shown  better  by 
the  following  data  on  the  actual  equipments  of  a  number  of  these  plants 
than  by  any  amount  of  general  statements  on  the  subject.  Reference 
should  also  be  made  to  Chapter  XXXI,  where  general  crushing  practice 
is  discussed. 

Plant  No.  1.     Uses  limestone  and  shale. 

Limestone  Shale 

1  Gates  crusher  1  Gates  crusher 


Plant  No. 


Plant  No.  3. 


1  Mosser  drier 

1  kominuter 

4  tube  mills 

4  kilns 

Limestone  and  shale. 

Limestone  Shale 


1  crusher 

1  rotary  drier 

1  Williams  mill 

2  tube  mills 
2  kilns 

Limestone  and  shale. 

Limestone 
1  crusher 
1  rotarv  drier 


Shale 

1  tunnel  drier 
1  crusher 


1  dry-pan  to  30-mesh 

2  Raymond  pulverizers 

3  kilns,  50  feet 


PREPARING  THE  MIXTURE  FOR  THE  KILN. 


409 


Plant  No.  4.     Limestone  and  shale. 

Limestone  Shale 

2  Alton  crushers  1  dry-pan  to  8-mesh 

1  Bonnot  drier  1  rotary  drier 

10  sets  rolls  2  tube  mills 

9  sets  Sturtevant  emery  mills 


4  intermittent  tube  mills 
4  kilns 

Plant  No.  5.     Uses  fairly  hard  limestone,  with  shale. 

Limestone  Shale 

1  Gates   crusher,    coarse  rock   sold;     1  disintegrator 

screenings  used  in  cement  plant     2  Bonnot  rotary  driers 

2  Bonnot  rotary  driers 


3  kominuters  to  20-mesh 

4  tube  mills  to  92%  through  100-mesh 
8  kilns 


Plant  No.  6.     Limestone  and  shale. 

Limestone  Shale 

1  Gates  crusher  1  Gates  crusher 


1  rotary  drier 

3  ball  mills 

4  tube  mills 
6  kilns 


Plant  No.  7.     Uses  hard  limestone  and  shale. 


Limestone 
2  Austin  crushers 
2  Bonnot  driers 
2  Krupp  ball  mills 


Shale 

1  Sturtevant  crusher 

2  Bonnot  driers 

1  Bonnot  ball  mill 


Plant  No.  8. 


5  tube  mills 
10  kilns 

Limestone  and  shale. 
Limestone 


Shale 


1  Gates  crusher,  No.  5 
1  rotary  drier 
3  Williams  mills 
3  tube  mills 
6  kilns 


Plant  No.  9. 


Limestone  and  shale. 
Limestone 


2  crushers 

2  rotary  driers 

4  ball  mills 

6  tube  mills 

8  kilns 


Shale 


410  CEMENTS,  LIMES,  AND  PLASTERS. 

Plant  No.  10.    Limestone  and  cement  rock. 

Limestone  Cement  rock 


2  crushers 

2  rotary  driers 

6  ball  mills 

6  tube  mills 

.10  kilns      . 

1  .  v* 

Plant  No.  11.     Limestone  and  shale. 

Limestone  Shale 

1  crusher  1  disintegrator 

1  rotary  drier  1  rotary  drier    , 


2  kominuters 

2  Davidsen  tube  mills 

6  kilns,  60  feet 

Plant  No.  12.     Uses  marl  and  clay  in  a  dry  process. 

Marl  Clay 

1  rotary  drier  1  rotary  drier 

2  tube  mills 

3  kilns 

List  of  references  on  dry-process  plants  and  methods. — The  follow- 
ing papers  describe  plants  using  the  dry  process  or  details  connected 
with  that  process. 

Haight,  H.     New  works  of  the  William  Krause  &  Sons  Cement  Co.,  Martins 

Creek,  Pa.     Engineering  Record,  March  31,  1900.     Cement  Industry, 

pp.  107-116.     1900. 
Humphrey,  R.  L.     Plant  of  the  Buckhorn  Portland  Cement  Co.  [W.  Va.]. 

Engineering  News,  vol.  50,  pp.  408-414.     Nov.  5,  1903. 
Lathbury,  B.  B.,  and  Spackman,  H.  S.     Portland  Cement  Co.  of  Utah  [Salt 

Lake,  Utah].     The  Rotary  Kiln,  p.  127.     1902. 
Lathbury,  B.  B.,  and  Spackman,  H.  S.     Rotary  plant  of  the  American  Cement 

Co.,  Egypt,  Pa.     The  Rotary  Kiln,  pp.  66-71.     1902. 
Lathbury,  B.  B.,  and  Spackman,  H.  S.     Plant  of  the  Lawrence  Cement  Co., 

Siegfried,  Pa.     Engineering  Record,  May  12,  1900.     Cement  Industry, 

pp.  117-131.     1900.     The  Rotary  Kiln,  pp.  96-109.     1902. 
Lathbury,  B.  B.,  and  Spackman,  H.  S.      Alsen's  American  Portland  Cement 

Works,  West  Camp,  N.  Y.     The  Rotary  Kiln,  pp.  52-65.     1902. 
Lewis,  F.  H.     The  Vulcanite  Portland  Coment  Company's  Works,  Vulcanite, 

N.  J.     Engineering  Record,  May  6,  1899.  Cement  Industry,  pp.  96-106. 

1900. 
Lewis,  F.  H.     The  Portland-cement  plant  of  the  Coplay  Cement  Co.,  Coplay, 

Pa.     Engineering  Record,  Dec.  18,  1897.    Cement  Industry,  pp.  20-32. 

1900. 
Lewis,  F.  H.     Mechanical  equipment  of   a  modern  Portland-cement  plant. 

Mineral  Industry,  vol.  11,  pp.  88-119.     1903. 


PREPARING   THE  MIXTURE  FOR  THE  KILN.  411 

Meade,  R.  K.  The  plant  of  the  Northampton  Portland  Cement  Co.,  Pa.  En- 
gineering Record,  vol.  48,  pp.  182,  183.  Dec.  5,  1903. 

Meyer,  H.  C.  New  works  of  the  Coplay  Cement  Co.,  Coplay,  Pa.  Engineering 
Record,  Feb.  27,  1900.  Cement  Industry,  pp.  69-77.  1900. 

Meyer,  H.  C.  The  works  of  the  Nazareth  Portland  Cement  Co.,  Nazareth, 
Pa.  Engineering  Record,  Dec.  16,  1899.  Cement  Industry,  pp.  85-95, 
1900. 

Meyer,  H.  C.  The  Whitehall  Portland  Cement  Works,  Cementon,  Pa.  En- 
gineering Record,  Sept.  15,  1900.  Cement  Industry,  pp.  142-150.  1900. 

Stanger,  W.  H.,  and  Blount,  B.  [The  Atlas  Portland- cement  plant,  Pa.] 
Proc.  Inst.  Civil  Engineers,  vol.  145,  pp.  57-68. 

Vredenburgh,  W.  The  Virginia  Portland  Cement  Co.  'a  Works,  Craigsville,  Va. 
Engineering  Record,  July  28, 1900.  Cement  Industry,  pp.  132-141.  1900. 

Anon.  The  Almendares  Portland  Cement  Works,  Cuba.  Engineering  Record, 
vol.  49,  pp.  36-38.  Jan.  9,  1904. 

Anon.     Edison  Portland  Cement  Company  [N.  J.].      Iron  Age,  Dec.  24,  1903. 

Anon.  The  works  of  the  Edison  Portland  Cement  Co.,  near  Stewartsville, 
N.  J.  Engineering  Record,  vol.  48,  pp.  796-802.  Dec.  26,  1903. 

Anon.  The  Edison  Portland  Cement  Works  at  New  Village,  N.  J.  Engineer- 
ing News,  vol.  50,  pp.  555-559.  1903. 

Anon.  Alsen's  American  Portland  Cement  Works,  N.  Y.  Engineering  Record, 
vol.  47,  pp.  10-13.  Jan.  3,  1903. 

Anon.  Plant  of  the  Hudson  Portland  Cement  Co.,  at  Hudson,  N.  Y.  En- 
gineering News,  vol.  50,  pp.  70-71.  July  23,  1903. 

(2)  Methods  Used  with  Slag-Limestone  Mixtures. 

While  the  manufacture  of  Portland  cement  from  a  mixture  of 
slag  and  limestone  is  similar  in  general  theory  and  practice  to  its  manu- 
facture from  a  limestone-clay  or  other  dry  raw  materials,  certain  inter- 
esting differences  occur  in  the  preparation  of  the  mixture.  In  the 
following  paragraphs  the  general  methods  of  preparing  mixtures  of 
slag  and  limestone  for  use  in  Portland-cement  manufacture  will  first 
be  noted,  after  which  certain  processes  peculiar  to  the  use  of  this  par- 
ticular mixture  will  be  described  separately. 

General  methods. — After  it  had  been  determined  that  the  puzzo- 
lan  cement  made  *  by  mixing  slag  with  lime  without  subsequent 
burning  of  the  mixture  was  not  an  entirely  satisfactory  structural 
material,  attention  was  soon  directed  toward  the  problem  of  making  a 
true  Portland  cement  from  such  slag.  The  blast-furnace  slags  com- 
monly available,  while  carrying  enough  silica  and  alumina  for  a  cement 
mixture,  are  too  low  in  lime  to  be  suitable  for  Portland  cement.  Addi- 

*See  Part  VII. 


412  CEMENTS,  LIMES,  AND   PLASTERS. 

tional  lime  must  be  added,  usually  in  the  form  of  limestone,  the  slag 
and  limestone  must  be  well  mixed  and  the  mixture  properly  burned. 
The  general  methods  for  accomplishing  the  proper  mixture  of  the  mate- 
rials vary  in  details.  It  seems  probable  that  the  first  method  used 
in  attempting  to  make  a  true  Portland  cement  from  slag  was  to  dump 
the  proper  proportion  of  limestone,  broken  into  small  lumps,  into  molten 
slag.  The  idea  was  that  both  mixing  and  calcination  could  thus  be 
accomplished  in  one  stage;  but  in  practice  it  was  found  that  the  result- 
ing cement  was  variable  in  composition  and  always  l^ow  in  grade.  This 
method  has  accordingly  fallen  into  disuse,  and  at  present  three  different 
general  processes  of  preparing  the  mixture  are  practiced  at  different 
European  and  American  plants. 

1.  The  slag  is  granulated,  dried,  and  ground,  while  the  limestone 
is  dried  and  ground  separately.     The  two  materials  are  then  mixed 
in  proper  proportions,  the  mixture  is  finely  pulverized  in  tube  mills, 
and  the  product  is  fed  in  a  powdered  state  to  rotary  kilns. 

2.  The  slag  is  granulated,  dried,  and  mixed  with  slightly  less  than 
the  calculated  proper  amount  of  limestone,  which  has  been  previously 
dried   and  powdered*     To   this  mixture   is   added  sufficient  powdered 
slaked  lime  (say  2  to  6  per  cent)  to  bring  the  mixture  up  to  correct 
composition.     The  intimate  mixture  and  final  reduction  are  then  accom- 
plished in  ball  and  tube  mills.     About  8  per  cent  of  water  is  then  added, 
and  the  slurry  is  made  into  bricks,  which  are  dried  and  burned  in  a 
dome  or  chamber  kiln. 

3.  Slag  is  granulated  and  mixed,  while  still  wet,  with  crushed  lime- 
stone in  proper  proportions.     This  mixture  is  run  through  a  rotary 
calciner,  heated  by  waste  kiln  gases,  in  which  the  temperature  is  suffi- 
cient not  only  to  dry  the   mixture  but   also  to  partly  powder  it  and 
to  reduce  most  of  the  limestone  to  quicklime.     The  mixture  is  then 
pulverized  and  fed  into  rotary  kilns. 

Of  the  three  general  processes  above  described  the  second  is  unsuited 
to  American  conditions.  The  first  and  third  are  adapted  to  the  use 
of  the  rotary  kiln.  The  third  seems  to  be  the  most  economical,  and 
has  given  remarkably  low  fuel  consumption  in  practice,  but  so  far  has 
not  been  taken  up  in  the  United  States. 

Certain  points  of  manufacture  peculiar  to  the  use  of  mixtures  of 
slag  and  limestone  will  now  be  described. 

Composition  of  the  slag. — The  slags  available  for  use  in  Portland- 
cement  manufacture  are  of  quite  common  occurrence  in  iron-producing 
districts.  Those  best  suited  for  such  use  are  the  more  basic  blast- 
furnace slags,  and  the  higher  such  slags  run  in  lime  the  more  available 


PREPARING  THE  MIXTURE  FOR  THE   KILN.  413' 

they  are  for  this  use.  The  slags'  utilized  will  generally  run  from  30  to 
40  per  cent  lime.  The  presence  of  over  3  per  cent  or  so  of  magnesia 
in  a  slag  is,  of  course,  enough  to  render  its  use  as  a  Portland-cement 
material  inadvisable;  and  on  this  account  slags  from  furnaces  using 
dolomite  (magnesian  limestone)  as  a  flux  are  unsuited  for  cement- 
manufacture.  The  presence  of  any  notable  percentage  of  sulphur  is 
also  a  drawback,  though,  as  will  be  later  noted,  part  of  the  sulphur 
in  the  slag  will  be  removed  during  the  processes  of  manufacture. 

Granulation  of  slag. — If  slag  be  allowed  to  cool  slowly,  it  solidifies 
into  a  dense,  tough  material,  which  is  not  readily  reduced  to  the  requisite 
fineness  for  a  cement  mixture.  If  it  be  cooled  suddenly,  however,  as 
by  bringing  the  stream  of  molten  slag  into  contact  with  cold  water, 
the  slag  is  " granulated",  Le.,  it  breaks  up  into  small  porous  particles. 
This  granulated  slag  or  "slag  sand"  is  much  more  readily  pulverized 
than  a  slowly  cooled  slag;  its  sudden  cooling  has  also  intensified  the 
chemical  activity  of  its  constituents  so  as  to  give  it  hydraulic  properties, 
while  part  of  the  sulphur  contained  in  the  original  slag  has  been  removed. 
The  sole  disadvantage  of  the  process  of  granulating  slag  is  that  the 
product  contains  20  to  40  per  cent  of  water,  which  must  be  driven  off 
before  the  granulated  slag  is  sent  to  the  grinding  machinery. 

In  practice  the  granulation  of  the  slag  is  effected  by  directing  the 
stream  of  molten  slag  direct  from  the  furnace  into  a  sheet-iron  trough. 
A  small  stream  of  water  flows  along  this  trough,  the  quantity  and  rate 
of  flow  of  the  water  being  regulated  so  as  to  give  complete  granulation 
of  the  slag  without  using  an  excessive  amount  of  water.  The  trough 
may  be  so  directed  as  to  discharge  the  granulated  slag  into  tanks  or 
into  box  cars,  which  are  usually  perforated  at  intervals  along  the  sides 
so  as  to  allow  part  of  the  water  to  drain  off. 

Drying  the  slag. — As  above  noted,  the  granulated  slag  may  carry 
from  20  to  40  per  cent  of  water.  This  is  renewed  by  treating  the  slag 
in  rotary  driers.  In  practice  such  driers  give  an  evaporation  of 
8  to  10  pounds  of  water  per  pound  of  coal.  The  practice  of  slag-dry- 
ing is  very  fully  described  in  Part  VII  of  this  volume,  pages  649-652, 
where  figures  and  descriptions  of  various  driers  are  also  given,  with 
data  on  their  evaporative  efficiency.  As  noted  earlier  in  this  article, 
one  of  the  methods  of  manufacturing  Portland  cement  from  slag 
puts  off  the  drying  of  the  slag  until  after  it  has  been  mixed  with  the 
limestone,  arid  then  accomplishes  the  drying  by  utilizing  waste  heat 
from  the  kilns.  Kiln  gases  could,  of  course,  be  used  anyway  in  the 
slag-driers,  but  it  so  happens  that  they  have  not  been  so  used  except, 
in  plants  following  the  method  in  question. 


414  CEMENTS,  LIMES,  AND  PLASTERS. 

Grinding  the  slag. — Slag  can  be  crushed  with  considerable  ease  to 
about  50-mesh,  but  notwithstanding  its  apparent  brittleness  it  is  diffi- 
cult to  grind  it  finer.  Until  the  introduction  of  the  tube  mill,  in  fact, 
it  was  almost  impossible  to  reduce  this  material  to  the  fineness  neces- 
sary for  a  cement  mixture,  and  the  proper  grinding  of  the  slag  is  still 
an  expensive  part  of  the  process,  as^compared  with  the  grinding  of 
limestone,  shales,  or  clay. 

Composition  of  the  limestone. — As  the  slag  carries  all  the  silica  and 
alumina  necessary  for  the  cement  mixture,  the  limestone  to  be  added  to 
it  should  be  simply  a  pure  lime  carbonate.  The  limestone  used  for  flux 
at  the  furnace  which  supplies  the  slag  will  usually  be  found  to  be  of 
suitable  composition  for  use  in  making  up  the  cement  mixture. 

Economics  of  using  slag-limestone  mixtures. — The  manufacture  of 
a  true  Portland  cement  from  a  mixture  of  slag  and  limestone  presents 
certain  undoubted  advantages  over  the  use  of  any  other  raw  materials, 
while  it  has  also  a  few  disadvantages. 

Probably  the  most  prominent  of  the  advantages  lies  in  the  fact 
that  the  most  important  raw  material — the  slag — can  usually  be  ob- 
tained more  cheaply,  than  an  equal  amount  of  natural  raw  material 
could  be  quarried  or  mined.  The  slag  is  a  waste  product,  and  a  trouble- 
some material  to  dispose  of,  for  which  reason  it  is  obtained  at  small 
expense  to  the  cement-plant.  Another  advantage  is  due  to  the  occur- 
rence of  the  lime  in  the  slag  as  oxide,  and  not  as  carbonate.  The  heat 
necessary  to  drive  off  the  carbon  dioxide  from  an  equivalent  mass  of 
limestone  is  therefore  saved  when  slag  forms  part  of  the  cement  mixture^ 
and  very  low  consumption  is  obtained  when  slag-limestone  mixture 
is  burned. 

Of  the  disadvantages,  the  toughness  of  the  slag  and  the  necessity 
for  drying  it  before  grinding  are  probably  the  most  important.  These 
serve  to  partly  counterbalance  the  advantages  noted  above.  A  third 
difficulty,  which  is  not  always  apparent  at  first,  is  that  of  securing  a 
proper  supply  of  suitable  slag.  Unless  the  cement-plant  is  closely 
connected  in  ownership  with  the  furnaces  from  which  its  slag  supply 
is  to  be  obtained,  this  difficulty  may  become  very  serious.  In  a  season 
when  a  good  iron  market  exists  the  furnace  manager  will  naturally 
give  little  thought  to  the  question  of  supplying  slag  to  an  independent 
cement-plant. 

The  advantages  of  the  mixture,  however,  seem  to  outweigh  its  dis- 
advantages, for  the  manufacture  of  Portland  cement  from  slag  is  now 
a  large  and  growing  industry  in  both  Europe  and  America.  Two  Port- 
land-cement plants  using  slag  and  limestone  as  raw  materials  have  been 


PREPARING  THE  MIXTURE  FOR  THE  KILN.  415 

established  for  some  time  in  this  country,  several  others  are  in  course  of 
construction  at  present,  and  it  seems  probable  that  in  the  near  future 
Alabama  will  join  Illinois  and  Pennsylvania  as  an  important  producer 
of  Portland  cement  from  slag. 

References  on  slag-limestone  mixtures. 

(The  more  important  articles  are  preceded  by  an  asterisk.) 

Eckel,  E.  C.     Preparation  of  slag  limestone  mixtures.     Municipal  Engineerhig, 

vol.  25,  pp.  227-230.     1903. 
Hughes,  0.  J.  D.     Portland  cement  from  slag.     U.  S.  Consular  Reports,  No. 

1700,  July  18,  1903. 

*  Jantzen.     Utilization  of  blast-furnace  slag.     Stahl  und  Eisen,  vol.  23,  pp. 

361-375.     1902.     Journ.  Iron  and  Steel  Inst.,  1903,  No.  1,  pp.  634-637. 
Kammerer.     Von  ForelPs  process  for  the  production  of  Portland  cement  from 
basic  slag.     Stahl  und  Eisen,  vol.  19,  p.  1088.     1899.     Journ.  Soc.  Chem. 
Industry,  vol.  19,  p.  48. 

*  Lathbury,  B.  B.,  and  Spackman,  H.  S.     The  Clinton  Cement  Company's 

plant,  Pittsburg,  Pa.     The  Rotary  Kiln,  pp.  82-85.     1902. 
May,  E.     Slag  (Portland)   cement.     Stahl  und  Eisen,  vol.    18,  pp.  205-211. 

1897.     Journ.  Iron  and  Steel  Inst.,  1898,  No.  1,  pp.  461-464. 
Schiele,  F.     Manufacture  of  Portland  cement  from  slag  at  Lollar,  Germany. 

Proc.  Inst.  Civ.  Engrs.,  vol.  145,  pp.  119-120.     1901. 
Steffens,  C.     Portland  cement  from  slag  in  Germany.     Stahl  und  Eisen,  vol.  20, 

pp.  1170-1171.    1900.  Journ.  Iron  and  Steel  Inst.,  1901,  No.  1,  pp.  439- 

440. 

Von  Forell,  C.     Patent  Portland  cement  from  slag.     Journ.  Soc.  Chem.  Indus- 
try, vol.  19,  p.  50.     1899. 
*Von  Schwarz,  C.     The  utilization  of  blast-furnace  slag.     Journ.  Iron  and 

Steel  Inst.,  1900,  No.  1,  pp.  141-152.     Engineering  News,  Sept.  27,  1900. 

Engineering  Record,  June  2,  1900. 

*  Von  Schwarz,  C.     Portland  cement  manufactured  from  blast-furnace  slag. 

Journ.  Iron  and  Steel  Inst.,  1903,  No.  1,  pp.  203-230. 

(3)  Blast-furnace  Methods  of  Making  Cement. 

Attempts   have   been   made   to   manufacture    Portland   cement   by 
mixing  the  raw  materials  without  grinding  and  burning  the  mixture 
•  to  a  state  of  complete  fusion  in  a  kiln  resembling  a  blast-furnace  in  de- 
sign and  action.    -The  Hurry  and  Seaman  patents  covering  a  method 
of  this  type  are  described  as  follows:* 

Raw  materials  containing  carbonate   of  lime,  silica,   and   alumina 
are  mixed  with  carbonaceous  fuel,  the  combustion  of  which  is  supported 

*  Journal  Soc.  Chem.  Industry,  vol.  21,  p.  1079.     1902 


416  CEMENTS,  LIMES,  AND  PLASTERS. 

by  a  blast  of  air  supplied  through  tuyeres,  and  a  pressure  about  10  to 
20  Ibs.  above  that  of  the  atmosphere  is  maintained  in  the  furnace, 
whereby  the  materials  are  melted,  the  molten  cement  being  afterward 
drawn  off,  cooled,  and  pulverized.  The  carbon  dioxide  derived  from  the 
carbonate  of  lime  is  reduced  to  carbonic  oxide  by  the  incandescent 
fuel,  and  in  this  atmosphere  any  oxide  of  iron  in  the  raw  materials  is 
said  to  be  reduced  to  metallic  iron,  which  sinks  and  can  ,thus  be  sepa- 
rated from  the  molten  cement,  whereby  a  superior  product  is  obtained. 
The  carbonate  of  lime  may  be  preliminarily  calcined  and  the  carbon 
dioxide  introduced  together  with  air  into  the  calcining  furnace,  where  it 
is  reduced  and  then  again  burned  to  carbon  dioxide.  The  increased  pres- 
sure is  maintained  either  by  arranging  the  height  of  the  kiln  so  that  the 
combustion  gases  formed  in  the  lower  part  are  prevented  from  escaping 
freely  by  the  height  of  the  mass  of  materials  above  or  by  a  throttle- 
valve  arranged  in  the  outlet  at  the  top  of  the  kiln. 

Von  Forell  has  taken  out  foreign  patents  on  processes  of  quite  similar 
type. 

(4)  Wet  Methods  of  Preparation. 

Wet  methods  of  preparing  Portland-cement  mixtures  date  back 
to  the  time  when  millstones  and  similar  crude  grinding  contrivances 
were  in  use.  With  such  imperfect  machinery  it  was  almost  impossible 
to  grind  dry  materials  fine  enough  to  give  a  good  Portland-cement  mix- 
ture. The  advent  of  good  grinding  machinery  has  practically  driven 
out  wet  methods  of  manufacture  in  this  country,  except  in  dealing 
with  materials  such  as  marls,  which  naturally  carry  a  large  percentage  of 
water.  Two  plants  in  the  United  States  do,  it  is  true,  deliberately 
add  water  to  a  limestone-clay  mixture;  but  the  effect  of  this  practice 
on  the  cost  sheets  of  these  remarkable  plants  is  not  encouraging. 

In  preparing  cement  mixtures  from  marl  and  clay,  a  few  plants  dry 
both  materials  before  mixing.  It  seems  probable  that  this  practice 
will  spread,  for  the  wet  method  of  mixture  is  inherently  expensive. 
At  present,  however,  almost  all  marl-plants  use  wet  methods  of  mixing, 
and  it  is  therefore  necessary  to  give  some  space  to  a  discussion  of  such 
methods. 

Certain  points  regarding  the  location,  physical  condition,  and  chem- 
ical composition  of  the  marls  and  clays  used  in  such  mixtures  have  impor- 
tant effects  upon  the  cost  of  the  wet  process.  As  regards  location  con- 
sidered on  a  large  scale,  it  must  be  borne  in  mind  that  marl  deposits 
of  workable  size  occur  only  in  the  Northern  States  and  in  Canada.  In 
consequence  the  climate  is  unfavorable  to  continuous  working  through- 
out the  year,  for  the  marl  is  usually  covered  with  water,  and  in  winter 


PREPARING  THE  MIXTURE  FOR  THE  KILN.  417 

it  is  difficult  to  secure  the  material.  In  a  minor  sense  location  is  still 
an  important  factor,  for  marl  deposits  necessarily  and  invariably  are 
found  in  depressions;  and  the  mill  must,  therefore,  just  as  necessarily 
be  located  at  a  higher  level  than  its  source  of  raw  material,  which  involves 
increased  expense  in  transporting  the  raw  material  to  the  mill. 

Glacial  clays,  which  are  usually  employed  in  connection  with  marl, 
commonly  carry  a  much  larger  proportion  of  sand  and  pebbles  than 
do  the  sedimentary  clays  of  more  southern  regions. 

The  effect  of  the  water  carried  by  the  marl  has  been  noted  in  an 
earlier  paper.  The  material  as  excavated  will  consist  approximately 
of  equal  weights  of  lime  carbonate  and  of  water.  This  on  the  face  of 
it  would  seem  to  be  bad  enough  as  a  business  proposition;  but  we 
find  that  in  practice  more  water  is  often  added  to  permit  the  marl  to 
be  pumped  up  to  the  mill. 

On  the  arrival  of  the  raw  materials  at  the  mill  the  clay  is  often  dried, 
in  order  to  simplify  the  calculation  of  the  mixture.  The  reduction  of 
the  clay  is  commonly  accomplished  in  a  disintegrator  or  in  edge-runner 
mills,  after  which  the  material  is  further  reduced  in  a  pug-mill,  suffi- 
cient water  being  here  added  to  enable  it  to  be  pumped  readily.  It  is 
then  ready  for  mixture  with  the  marl,  which  at  some  point  in  its  course 
has  been  screened  to  remove  stones,  wood,  etc.,  so  far  as  possible.  The 
slurry  is  further  ground  in  pug-mills  or  wet-grinding  mills  o/  the  disk 
type,  while  the  final  reduction  takes  place  commonly  in  wet-tube  mills. 
The  slurry,  now  containing  30  to  40  per  cent  of  solid  matter  and  70 
to  60  per  cent  of  water,  is  pumped  into  storage-tanks,  where  it  is  kept 
in  constant  agitation  to  avoid  settling.  Analyses  of  the  slurry  are 
taken  at  this  point,  and  the  mixture  in  the  tanks  is  corrected  if  found 
to  be  of  unsatisfactory  composition.  After  standardizing,  the  slurry 
is  pumped  into  the  rotary  kilns.  Owing  to  the  large  percentage  of 
water  contained  in  the  slurry  the  fuel  consumption  per  barrel  of  finished 
cement  is  30  to  50  per  cent  greater  and  the  output  of  each  kiln  corre- 
spondingly less  than  in  the  case  of  a  dry  mixture.  This  point  will,  how- 
ever, be  further  discussed  in  a  later  chapter. 

At  a  plant  working  a  rather  stiff  slurry  carrying  only  40  per 
cent  of  water  two  Bonnot  tube  mills,  using  25  H.P.  each,  handled 
together  4000  cubic  feet  of  slurry  in  twenty-four  hours,  equivalent, 
to  a  production  of  300  or  more  barrels  of  cement  per  day.  This  is; 
equivalent  to  a  power  consumption  of  a  little  less  than  4  H.P.  hours  per 
barrel  of  finished  cement.  The  clay  contained  in  the  slurry  had  been 
passed  through  a  dry-pan  and  the  slurry  was  then  mixed  and  ground 
to  some  extent  in  a  pug-mill. 


418  CEMENTS,  LIMES,  AND  PLASTERS. 

A  Bonnot  22' X  5'  tube  mill  used  at  a  marl-plant  on  not  very  wet 
slurry  ground  about  20  to  30  barrels  per  hour,  taking  30  H.P.  in  doing 
so.  This  slurry  had  not  been  previously  treated  except  by  passing  it 
through  a  stone  separator,  so  that  the  total  power  for  grinding  raw 
material  at  this  plant  was  from  1  H.P.  to  1J  H.P.  per  barrel  cement. 

At  another  plant  a  Bonnot  16-foot  tube  mill  ground  12  barrels  per 
hour  raw  wet  mix,  taking  15  to  20  'H.P.  in  doing  so,  the  marl  having 
previously  been  passed  through  a  stone  separator  and  pug-mill  and  the 
clay  through  dry-pans. 

Other  plants  report  slightly  different  results  with  wet-tube  mills. 
To  sum  up,  from  all  data  it  seems  that  the  preparation  of  a  wet  mix 
in  tube  mills  will  usually  require  from  1  H.P.  hour  to  2  H.P.  hours 
per  barrel  cement.  The  power  and  product,  however,  will  vary  greatly 
with  the  percentage  of  water  in  the  mix,  as  well  as  with  the  hardness 
of  the  particular  marl  and  clay  employed. 

The  highest  power  consumption  per  barrel  was  shown  by  a  plant 
which  required  3.9  H.P.  hours  per  barrel  for  preparing  its  raw  mate- 
rials for  the  kiln.  The  marl  used  at  this  plant  is  unusually  hard,  and 
the  mixture  is  made  with  less  water  than  usual.  This  gives  a  fairly 
high  kiln  efficiency  (100  barrels  per  day  per  kiln  with  a  fuel  consump- 
tion of  160  Ibs.  coal  per  barrel),  but  it  largely  increases  the  work  to 
be  done  by  the  grinding  machinery  on  the  raw  side.  Several  of  the 
grinding-mills  used  at  this  plant  are,  in  addition,  very  inefficient  types, 
and  to  this  combination  of  unfavorable  conditions  is  to  be  ascribed 
the  high-power  consumption  on  the  raw  side  of  the  plant. 

All  of  the  tanks  containing  slurry  must  be  provided  with  some  appli- 
ance for  agitating  the  mixture  or  otherwise  the  heavier  portion  would 
settle  at  the  bottom  of  the  tanks,  leaving  fairly  clear  water  above.  Three 
different  methods  of  agitating  are  in  use  at  various  marl-plants: 

1.  A  vertical  central  shaft  equipped  with  long  arms  or  paddles; 

2.  A  horizontal  shaft  crossing  the  tank  a  little  above  its  bottom 

and  fitted  with  screw  blades; 

3.  The  injection  at  intervals  of  jets  of  compressed  air. 

Any  of  these  three  devices  gives  fairly  good  results,  but  none  of  them 
seems  entirely  satisfactory  to  the  managers  of  the  plants  in  which  they 
are  installed.  The  first  two  use  an  unexpectedly  large  amount  of  power. 

It  may  be  of  interest,  for  comparison  with  the  above  description 
of  the  wet  process  with  rotary  kilns,  to  insert  a  description  of  the  semi- 
wet  process  as  carried  on  a  few  years  ago  at  the  dome-kiln  plant  of  the 
Empire  Portland  Cement  Company  of  Warners,  N.  Y.  The  plant  has 
been  remodeled  since  that  date,  but  the  processes  formerly  followed 


PREPARING  THE  MIXTURE  FOR  THE  KILN.  419 

are  still  of  interest,  as  they  resulted  in  a  high-grade,  though  expensive, 
product. 

At  the  Empire  plant  the  marl  and  clay  are  obtained  from  a  swamp 
about  three  fourths  of  a  mile  from  the  mill.  A  revolving  derrick  with 
clam-shell  bucket  was  employed  for  excavating  the  marl,  while  the 
clay  was  dug  with  shovels.  The  materials  are  taken  to  the  works  over 
a  private  narrow-gauge  road,  on  cars  carrying  about  three  tons  each, 
drawn  by  a  small  locomotive.  At  the  mill  the  cars  were  hauled  up 
an  inclined  track,  by  means  of  a  cable  and  drum,  to  the  mixing  floor. 

The  clay  was  dried  in  three  Cummer  "salamander"  driers,  after 
which  it  was  allowed  to  cool,  and  then  carried  to  the  mills.  These  mills 
were  of  the  Sturtevant  "  rock-emery  "  type,  and  reduced  the  clay  to 
a  fine  powder,  in  which  condition  it  was  fed,  after  being  weighed,  to  the 
mixer.  The  marl  was  weighed  and  sent  directly  to  the  mixer,  no  pre- 
liminary treatment  being  necessary.  The  average  charge  was  about 
25  per  cent  clay  and  about  75  per  cent  marl. 

The  mixing  was  carried  on  in  a  mixing  pan  12  feet  in  diameter,  in 
which  two  large  rolls,  each  about  5  feet  in  diameter  and  16-inch  face, 
ground  and  mixed  the  materials  thoroughly.  The  mixture  was  then 
sampled  and  analyzed,  after  which  it  was  carried  by  a  belt  conveyor 
or  two  pug-mills,  where  the  mixing  was  completed  and  the  slurry  formed 
into  slabs  about  3  feet  long  and  4  to  5  inches  in  width  and  height.  These 
on  issuing  from  the  pug-mill  were  cut  into  a  number  of  sections,  so 
as  to  give  bricks  about  6  inches  by  4  inches  by  4  inches  in  size.  The 
bricks  were  then  placed  on  slats,  which  were  loaded  on  rack  cars  and 
run  into  the  drying  tunnels.  The  tunnels  were  heated  by  waste  gases 
from  the  kilns  and  required  from  twenty-four  to  thirty-six  hours  to 
dry  the  bricks. 

After  drying,  the  bricks  were  fed  into  dome  kilns,  twenty  of  which 
were  in  use,  being  charged  with  alternate  layers  of  coke  and  slurry 
bricks.  The  coke  charge  for  a  kiln  was  about  four  or  five  tons,  and 
this  produced  20  to  26  tons  of  clinker  at  each  burning,  thus  giving  a 
fuel  consumption  of  about  20  per  cent,  as  compared  with  the  40  per 
cent  or  so  required  in  the  rotary  kilns  using  wet  materials.  From 
thirty-six  to  forty  hours  were  required  for  burning  the  charge.  After 
cooling,  the  clinker  was  shoveled  out,  picked  over  by  hand,  and  reduced 
in  a  Blake  crusher,  Smidth  ball  mills,  and  Davidsen  tube  mills. 


420  CEMENTS,  LIMES,  AND  PLASTERS. 


Actual  Equipment  of  Wet-process  Plants. 

Plant  No.  1.  Uses  a  hard    limestone  and  a  clay  in  a  wet  process. 

Limestone  Clay 

2  crushers 


4'ballmilig 
4  wet  paddle  mills 
4  wet  tube  mills 
10  kilns 

Plant  No.  2.  Uses  a  fairly  hard  limestone  and  a  snale  in  a  wet  process. 

Limestone  Shale 

1  Gates  crusher  to  3^  inches  2  Williams  mills 

3  small  Gates  crushers  to  J  inch 


3  rotary  driers 

21  Griffin  mills  to  90%  through  100-mesh 

3  pug-mills 

15  slurry  tanks 

21  kilns 

Plant  No.  3.  Marl  and  clay. 

Marl  Clay 

1  rotary  drier 
1  dry-pan 

1  pug-mill,  40%  water 

2  Bonnot  tube  mills 

3  kilns,  60  feet 

Plant  No.  4-  Marl  and  clay. 

Marl  Clay 

1  stone  separator  1  dry-pan 

2  pug-mills 

4  Bonnot  tube  mills 

5  kilns 

Plant  No.  5.  Marl  and  clay. 

Marl  Clay 

1  stone  separator 

Tanks 
1  wet  tube  mill 

Tanks 
3  kilns 

Plant  No.  6.  Marl  and  clay. 

Marl  Clay 

2  wet-pans 


3  Abbie  mills  2  wet  ball  mills 

j  3  wet  tube  mills 

13  kilns 


PREPARING  THE  MIXTURE  FOR  THE  KILN.  421 

Plant  No.  7.  Marl  and  shale. 

Marl  Shale 

1  stone  separator  2  dry-pans 

1  pug-mill 


6  Bonnot  tube  mills,  16  feet 
14  kilns 


Plant  No.  8.  Marl  and  day. 


Marl  Clay 

1  stone  separator.  1  pug-mili 

1  pug-mill 
3  tube  mills 
6  kilns 

Plant  No.  9.  Marl  and  clay. 

Marl  Clay 

1  stone  separator  | 

2  wet-pans 
4  tube  mills 
14  kilns 

Plant  No.  10.  Marl  and  clay. 

Marl  Clay 

1  stone  separator  1  rotary  drier 

1  pug-mill 
4  tube  mills 
6  kilns,  70  feet 
4  kilns,  60  feet 

Plant  No.  11.  Marl  and  shale. 

Marl  Shale 

1  stone  separator          1  rotary  drier 
1  Williams  mill 


1  pug-mill 

2  tube  mills 

9  kilns,  70  feet 

List  of  references  on  wet-process  plants  and  methods. — The  following 
papers,  mostly  descriptive  of  individual  wet-process  plants,  contain 
sufficiently  detailed  data  on  methods  and  machinery  to  be  worth  refer- 
ring to  as  sources  of  further  information.  For  convenience  of  reference, 
the  plants  have  been  separately  named,  though  at  the  cost  of  some 
space. 

Grimsley,  G.  P.  A  new  Portland-cement  mill  in  the  gas  fields  of  Kansas 
[lola].  Engineering  and  Mining  Journal,  Feb.  16,  1901. 

Lathbury,  B.  B.  The  Michigan  Alkali  Company's  plant  for  manufacturing 
Portland  cement  from  caustic-soda  waste.  Engineering  News,  June  7, 
1900. 


422  CEMENTS,  LIMES,  AND  PLASTERS. 

Lathbury,  B.  B.,  and  Spackman,  H.  S.  The  Michigan  Alkali  Co.'s  plant,  Wyan- 
dotte,  Mich.  The  Rotary  Kiln,  pp.  110-119.  1902. 

Lathbury,  B.  B.,  and  Spackman,  H.  S.  Detroit  Portland  Cement  Co.,  Fenton, 
Mich.  The  Rotary  Kiln,  pp.  86-95.  1902. 

Lathbury,  B.  B.,  and  Spackman,  H.  S.  Wabash  Portland  Cement  Co.,  Stroh, 
Ind.  The  Rotary  Kiln,,  pp.  128-133.  1902. 

Lathbury,  B.  B.,  and  Spackman,  H.  S.  Alma  Portland  Cement  Co.,  Welleston, 
Ohio.  The  Rotary  Kiln,  pp.  44-51.  1902. 

Lathbury,  B.  B.,  and  Spackman,  H.  S.  Castalia  Portland  Cement  Co.,  Cas- 
talia,  Ohio.  The  Rotary  Kiln,  pp.  78-81.  1902. «. 

Lathbury,  B.  B.,  and  Spackman,  H.  S.  Beaver  Portland  Cement  Co.,  Marl- 
bank,  Ontario.  The  Rotary  Kiln,  pp.  74-77.  1902. 

Lathbury,  B.  B.,  and  Spackman,  H.  S.  Plant  of  the  Aalborg  Portland  Cement 
Fabrik,  Aalborg,  Denmark.  The  Rotary  Kiln,  pp.  42-43.  1902. 

Lewis,  F.  H.  The  plant  of  the  Bronson  Portland  Cement  Co.,  Bronson,  Mich. 
Engineering  Record,  April  30, 1898.  Cement  Industry,  pp.  33-44.  1900. 

Lewis,  F.  H.  The  plant  of  the  Michigan  Portland  Cement  Co.,  Coldwater, 
Mich.  Engineering  Record,  Feb.  25,  1899.  Cement  Industry,  pp. 
78-84.  1900. 

Lewis,  F.  H.  The  Empire  Portland-cement  plant,  Warners,  N.  Y.  Engineer- 
ing Record,  July  16,  1898.  Cement  Industry,  pp.  45-51.  1900. 

Lewis,  F.  H.  The  Buckeye  Portland-cement  plant,  near  Bellefontaine,  Ohio. 
Engineering  Record,  Oct.  15,  1898.  Cement  Industry,  pp.  52-59.  1900. 

Lewis,  F.  H.  Western  Portland  Cement  Co.'s  plant,  Yankton,  S.  D.  Engi- 
neering Record,  Nov.  19,  1898.  Cement  Industry,  pp.  60-68.  1900. 

Russell,  I.  G.  The  Portland-cement  industry  in  Michigan.  19th  Ann.  Rep. 
U.  S.  Geol.  Survey,  pt.  3,  pp.  629-685.  1902. 

Simmons,  W.  H.  [Plant  at  Bronson,  Michigan.]  Proc.  Inst.  Civ.  Engrs., 
vol.  145,  pp.  120-121.  1901. 

Stanger,  W.  H.,  and  Blount,  B.  [Plant  at  Bronson,  Mich.]  Proc.  Inst.  Civ. 
Engrs.,  vol.  145,  pp.  68-69.  1901. 

Anon.  Plant  and  buildings  of  the  Hecla  Portland  Cement  and  Coal  Co.,  Mich. 
Engineering  News,  vol.  51,  pp.  243-245.  1904. 

General  Crushing  Practice. 

The  crushing  and  grinding  practice  in  cement-making  is  so  important 
a  part  of  the  manufacture,  and  so  closely  connected  with  the  financial 
success  or  failure  of  the  plant,  that  it  requires  special  consideration, 
both  as  to  general  methods  and  in  regard  to  the  special  types  of  machinery 
employed.  In  the  present  section  certain  features  will  be  discussed 
which  are  common  to  both  the  wet  and  dry  methods  of  preparation, 
while  the  following  chapter  will  be  devoted  to  a  description  of  the 
various  standard  types  of  crushing  and  grinding  machinery. 


PREPARING  THE  MIXTURE  FOR  THE  KILN.  423 

Necessity  for  fine  grinding. — The  necessity  for  very  fine  grinding 
of  the  raw  mixture,  if  a  sound  and  volume-constant  cement  is  to  be 
obtained,  was  early  stated  by  Newberry,*  and  the  value  of  such  fine 
grinding  has  been  recently  expressed  in  the  quantitative  form  by  the 
experiments  of  Professor  Campbell,  f 

To  secure  a  sound  and  volume-constant  cement  it  is  necessary  that 
the  raw  mixture  be  very  finely  ground.  Other  things  being  equal,  the 
finer  the  grinding  of  the  raw  mixture  the  better  will  be  the  resulting 
cement.  The  degree  of  fineness  necessary  to  secure  a  given  grade  of 
cement  will  depend  upon: 

(a)  The  percentage  of  lime  in  the  mixture.  The  higher  the  percentage 
of  lime  in  the  mixture,  the  finer  the  raw  mixture  must  be  ground,  because 
the  chances  of  getting  an  unsound  or  expensive  cement  will  increase 
as  the  percentage  of  lime  rises,  and  this  tendency  will  have  to  be  coun- 
teracted by  greater  fineness  of  grinding. 

(6)  The  carefulness  with  which  the  materials  have  been  mixed* 
The  more  careful  and  thorough  the  mixture,  the  less  care  need  be  be- 
stowed upon  the  grinding,  and  vice  versa. 

(c)  The  character  of  the  raw  materials.     This  point,  which  has  been 
emphasized   by    Newberry,*  is  of  great  importance.      When    a   very 
pure  limestone  or  marl  is  mixed  with  a  clay  or  shale,  the  grinding 
must  be  much  finer  than  in  the  plants  (such  as  those  in  the  Lehigh 
district  of  Pennsylvania)   where  a  highly  argillaceous  limestone   ("  ce- 
ment rock")  is  mixed  with  a  comparatively  small  quantity  of  purer 
limestone.     In  the  latter  case  the  coarser  particles  of  the  argillaceous 
limestone  will  be  so  near  in  chemical  composition  to  the  proper  mixture 
as  to  do  little  harm  to  the  resulting  cement,  even  if  both  the  grinding 
and  the  mixing   should   be  incompletely  accomplished,   while  in   the 
former  case,  where  a  pure  limestone  or  marl  is  mixed  with  clay  or  shale, 
both  of   the    constituents  are  very  different  in  composition  from  the 
proper  mixture,  and  coarse  particles  will  therefore  be  highly  injurious 
to  the  cement. 

(d)  The  duration  of  the  burning.     In  the  old-fashioned  dome  kilns, 
where  the  mixture  was  exposed  to  the  action  of  heat  for  a  week  or  more, 
the  duration  of  the  burning  compensated  in  some  degree  for  the  lack 
of  thoroughness  in  grinding  or  mixing.     In  modern  rotary  kilns,  how- 
ever, in  which  the  mixture  is  burned  for  only  an  hour  or  so,  this  aid  can- 
not be  counted  on,  and  both  grinding   and  mixing  must  therefore  be 
done  more  carefully. 

*  20th  Ann.  Rept.  U.  S  Geol.  Survey,  pt.  6,  p.  545. 
f  Journ.  Am.  Chem.  Soc.,  vol.  25,  p.  40  et  seq. 


424  CEMENTS,  LIMES,  AND  PLASTERS. 

Actual  fineness  attained. — After  its  final  reduction,  and  when  ready 
for  burning,  the  mixture  will  usually  run  from  90  to  95  per  cent  through 
.a  100-mesh  sieve.  In  the  plants  of  the  Lehigh  district  the  mixture 
is  rarely  crushed  as  fine  as  when  limestone  and  clay  are  used.  New- 
berry  *  has  pointed  out  in  explanation  for  this  that  an  argillaceous 
limestone  (cement  rock)  mixed  with  #  comparatively  small  quantity 
of  purer  limestone,  as  in  the  Lehigh  plants,  requires  less  thorough  mix- 
ing and  less  fine  grinding  than  when  a  mixture  of  limestone  and  clay 
(or  marl  and  clay)  is  used,  for  even  the  coarser  particles  of  the  argilla- 
ceous limestone  will  vary  so  little  in  chemical  composition  from  the 
proper  mixture  as  to  affect  the  quality  of  the  resulting  cement  but 
little  should  either  mixing  or  grinding  be  incompletely  accomplished. 

A  very  good  example  of  typical  Lehigh  Valley  grinding  of  raw  mate- 
rial is  afforded  by  a  specimen  examined  f  by  Prof.  E.  D.  Campbell.  This 
.specimen  of  raw  mix  ready  for  burning  was  furnished  by  one  of  the 
best  of  the  eastern  Pennsylvania  cement-plants.  A  mechanical  analysis 
of  it  showed  the  following  results. 

Mesh  of  sieve 50  100          200 

Per  cent  passing 96.9         85.6        72.4 

Per  cent  residue 3.1         14.4         27.6 

The  material,  therefore,  is  so  coarsely  ground  that  only  a  trifle  over 
-85  per  cent  passes  a  100-mesh  sieve. 

Bleininger  has  recently  published  the  results  of  a  series  of  tests 
for  fineness,  made  on  the  raw  mixtures  used  by  various  plants.  The 
results  are  given  in  Table  175. 

Gradual  vs.  one-stage  reduction. — This  question  is  now  of  little 
more  than  theoretical  interest,  as  almost  all  cement-plants  seem  to 
Tiave  given  the  same  decision  in  regard  to  it  Until  within  the  past 
few  years,  examination  of  a  number  of  cement-plants  would  have 
developed  the  fact  that  two  radically  different  systems  of  reduction 
were  in  use.  Reference  is  made  to  the  "gradual"  and  "one-stage" 
methods. 

In  those  earlier  days  many  plants,  after  preliminary  treatment  in 
a  coarse  crusher,  completed  the  entire  process  of  further  reduction  in 
a  Griffin  mill  or  ball  mill,  for  it  must  be  recollected  that  the  latter  mill 
was  introduced  earlier  than  its  companion,  the  tube  mill,  and  was  at 
first  expected  to  do  the  work  now  done  by  both. 

I  *  20th  Ann.  Rep.  U.  S.  Geol.  Survey,  pt.  6,  p.  545. 

t  Jour.  Amer.  Chem.  Soc.,  vol.  25,  p.  39. 


PREPARING  THE  MIXTURE   FOR  THE  KILN. 


425 


TABLE  175. 
FINENESS  OF  RAW  Mix  AT  VARIOUS  PLANTS.     (BLEININGER.) 


J 

>» 

*jf 

si 

I-H     0> 

eir75 

tt 

PI 

PS 

111 

I 

1 

Raw  Materials. 

*i 

J3 

1 

§02 
0,^3 

y  c£ 

8« 

S£ 

OOQ 

N 

OJGO-* 

^  GOO 
§0 

2sl 

3=3 

1 

4) 

J2 

§ 

T5g 

T3S 

^  u 

c  -5 

cj  *  • 

goo 

fes 

| 

o 

IS 

1 

9 

Cd 

1 

rt 

i°° 
S 

r 

.2°"°' 
(2) 

sa 
& 

Mills. 

1 

Limestone  and  shale 

Dry 

Emery 

2.  CO 

9.89 

4.85 

16.93 

8.96 

8.70 

48.68 

2 

Cement    rock    and 

limestone  

Dry 

Griffin 

16.38 

11.57 

4  75 

16.21 

13.29 

7.61 

30  17 

£ 

Cement    rock    and 

limestone 

Dry 

Tube 

3  03 

7  42 

3  68 

23  77 

17  52 

10  26 

34  33 

4 

Limestone  and  clay 

Wet 

7.40 

9.56 

2.48 

17.72 

8.96 

8.83 

45.05 

5 

Marl  and  clay 

Wet 

3  04 

5  50 

5  M 

20.31 

12  63 

9  61 

44  72 

6 

tt       it       «  < 

Wet 

30  46 

4  23 

?  17 

6.73 

10.61 

9  31 

47  06 

7 

1C             (  {             (I 

Wet 

2  48 

5  23 

?  47 

16.14 

14.22 

12  01 

47  46 

S 

(  C             (I            t  C 

Wet 

26.74 

6.99 

2.13 

10.52 

9.77 

7.67 

36.18 

At  present ,  however,  the  "  one-stage "  type  of  fine-reduction  prac- 
tice has  fallen  into  disuse.  It  has  been  gradually  modified  out  of  exist- 
ence, so  that  cement-mills  now  are  all  using  a  gradual  reduction  system. 

The  change  from  " one-stage"  to  "gradual"  has  been  effected  in 
two  opposite  ways,  according  to  whether  Griffin  or  ball  mills  were  in 
use  at  the  original  plant.  In  plants  using  the  Griffin  (or  Huntingdon) 
mill,  it  has  finally  become  the  general  practice  to  place  either  a  fine 
gyratory  crusher  or  a  set  of  fairly  fine  rolls  between  the  coarse  crusher 
and  the  Griffin  mill,  thus  insuring  that  the  material  fed  to  the  Griffin 
mill  shall  not  be  over  J  or  even  J  inch  in  size.  In  plants  using  ball 
mills,  the  change  has  taken  place  at  the  latter  end  of  the  series  by  put- 
ting in  a  tube  mill  after  the  ball  mill.  The  ball  mill,  instead  of  taking 
a  coarse  product  from  the  crusher  and  reducing  this  product  to  its  ulti- 
mate fineness,  has  been  made  an  intermediate  reducer,  the  final  reduc- 
tion taking  place  in  the  tube  mill. 

Present-day  systems.  —  Present-day  practice  in  the  reduction  of 
dry  raw  materials  may  therefore  be  summarized  as  in  the  following 
two  schedules.  The  two  schemes  differ  from  each  other  mainly  in 
the  mills  used. 

TYPE  A.     GRIFFIN  (OR  HUNTINGDON)  MILL  TYPE. 

1.  Gyratory  crusher to  about  1\  inches 

2.  Crusher  or  rolls "      "      i  to  £  inch 

3.  Griffin  or  Huntingdon  mill  "      "      85  to  95%  through  100-mesh 

TYPE  B.     BALL  (OR  WILLIAMS)  MILL  TYPE. 

1.  Gyratory  crusher to  about  2|  inches 

2.  Kominuter,   ball   mill    or 

Williams  mill ' '      "      20-  to  30-mesh 

3.  Tube  mill "      "      85  to  95%  through  100-mesh 


426  CEMENTS,  LIMES,  AND  PLASTERS. 

The  omission  of  separators  in  cement-plants. — Practically  every 
writer  who  has  discussed  the  crushing  practice  at  American  Portland- 
cement  plants  has  noted  and  deplored  the  absence  of  separators.  In 
spite  of  this  general  unity  of  opinion  in  the  subject,  only  a  few  plants, 
to  the  writer's  knowledge,  are  now  equipped  with  any  separators,  and 
none  have  as  many  as  might  "be  used.  **In  view  of  the  fact  that  Ameri- 
can Portland-cement  practice,  so  far  as  crushing  methods  are  concerned, 
is  to-day  far  ahead  of  crushing  practice  in  ore-treatment  works,  this 
apparent  disregard  of  one  great  principle  of  general,  crushing  practice 
seems  to  require  some  explanation.  It  will  not  do  merely  to  assume- 
that  separators  are  omitted  because  the  advantages  to  be  gained  from 
their  use  are  not  understood  by  designers  and  managers  of  cement- 
plants,  for  that  amounts  to  charging  a  peculiarly  expert  clan  of  mechan- 
ical experts  with  gross  ignorance.  In  the  opinion  of  the  writer,  the  gen- 
eral omission  of  separators  is  entirely  justified  by  certain  conditions 
peculiar  to  the  process  of  Portland-cement  manufacture,  and  the  general 
use  of  separators  would  be  a  serious  error  in  this  business.  As  this 
opinion  may  not  be  generally  accepted,  and  as  the  grounds  on  which 
it  is  based  have  never  been  discussed  in  print,  the  advantages  and  dis- 
advantages of  separators  may  be  worth  discussing  in  some  detail.  This 
is  particularly  necessary  because  the  writer  realizes,  and  freely  admits, 
that  the  views  which  he  holds  may  be  proven  to  be  based  on  incorrect 
premises.  In  that  case  a  relatively  brief  series  of  experiments,  which 
could  be  carried  on  in  any  cement-mill,  would  be  of  great  service  to  all 
interested  in  the  technology  of  the  cement  industry. 

Advantages  of  separators. — In  crushing  any  material,  if  the  only 
things  to  be  arrived  at  are  low  cost  of  crushing  per  ton  of  product  and 
high  tonnage  of  product  per  hour,  one  fact  may  be  regarded  as  firmly 
established;  that  is,  that  it  is  an  error  to  feed  to  any  machine  (of  the 
series  of  reducers  employed)  material  fine  enough  to  go  to  some  machine 
further  along  in  the  reduction  process.  Beginning  with  the  first  or 
coarsest  crusher  of  the  series,  while  most  of  its  product  will  only  be 
fine,  a  certain  part  of  its  product  will  be  sufficiently  fine  to  be  passed 
on  to  the  third  or  even  fourth  reducer.  If  this  be  done  the  product 
per  hour  of  the  series  will  be  greatly  increased,  each  machine  will  be 
working  on  material  of  fairly  uniform  size,  and  the  cost  of  crushing 
per  ton  will  be  greatly  reduced. 

Applying  this  to  the  Portland-cement  industry  it  is  probably  safe 
to  say  that  in  a  series  of  reducers  (consisting  for  example  of  a  coarse 
crusher,  a  fine  crusher,  a  Williams  or  ball  mills  and  tube  mills)  the 
product  per  hour  of  the  series  could  be  increased  at  least  50  per  cent 


PREPARING  THE  MIXTURE  FOR  THE  KILN.  427 

by  simply  placing  separators  between  each  of  the  steps  of  the  series. 
The  cost  of  crushing  per  ton  of  product  would  incidentally  be  decreased, 
but  not  in  quite  the  same  ratio. 

Disadvantages  of  separators. — In  view  of  the  enormous  gain  in  out- 
put that  would  be  secured  by  the  use  of  separation,  as  noted  in  the 
preceding  paragraph,  it  is  evident  that  the  disadvantages  attending 
their  use  must  also  be  very  great,  for  otherwise  every  cement-mill 
would  now  be  fully  equipped  with  them.  The  principal  disadvantages 
attending  the  use  of  separators  in  a  Portland-cement  plant  are  two : 

1.  Separators  destroy  the  uniformity  of  the  product. 

2.  Separators  prevent  the  attainment  of  very  great  fineness. 
These  two  objections  will  be  discussed  in  the  order  named.     It  is 

probable  that  the  second  is  in  actual  practice  the  more  important. 

Uniformity  of  product  destroyed  by  separators. — Throughout  the 
entire  course  of  cement  manufacturing  processes,  from  the  moment 
the  raw  materials  enter  the  will  until  the  finished  cement  is  packed 
the  object  of  the  manufacturer  is  to  attain  a  product  as  nearly  homo- 
geneous as  possible.  The  quality  of  the  cement  depends  in  large  part 
on  the  extent  to  which  his  attempts  to  secure  absolute  uniformity  have 
been  successful.  In  the  opinion  of  the  present  writer,  one  great  objec- 
tion to  the  introduction  of  separators  into  cement  practice  is  that  their 
use  will  tend  to  destroy  this  uniformity. 

The  action  of  separators  is  based  commonly  on  one  of  two  principles. 
They  take  advantage  either  (a)  of  differences  in  the  weight  of  particles 
or  (6)  in  differences  of  size  of  particles.  In  the  first  case,  the  separator, 
other  things  being  equal,  will  take  out  both  the  finer  particles  and  the 
particles  of  lowest  specific  gravity.  In  dealing  with  raw  mixtures  they 
will  tend  to  separate  the  clay  particles  from  the  limestone  particles. 
Separators  depending  for  their  action  on  the  differences  in  size  between 
the  particles  will  take  out  the  finer,  which,  other  things  being  equal, 
will,  of  course,  be  particles  of  the  constituent  which  is  most  readily 
pulverized.  Similar  effects  will  be  observed  if  separators  be  used  in 
the  progress  of  clinker-grinding,  for  the  lighter-burned,  more  readily 
ground  portions  will  be  separated  from  the  rest  and  the  uniformity 
of  the  product  will  be  destroyed. 

Great  fineness  prevented  by  separators. — If  in  a  plant  not  using  sepa- 
rators the  finest  grinders  be  adjusted  to  give  a  product  of  which  95 
per  cent  passes  a  100-mesh  sieve,  a  very  large  proportion  of  that  prod- 
uct (say  70  to  75  per  cent)  will  pass  a  200-mesh  sieve.  If  separators 
were  installed  throughout  the  plant,  and  the  same  adjustment  of  the 
fine  grinders  maintained,  a  product  passing  the  same  95  per  cent  through 


428  CEMENTS,  LIMES   AND  PLASTERS. 

a  100-mesh  sieve  would  probably  pass  not  over  60  per  cent  through 
200-mesh.  As  it  is  the  percentage  of  very  finely  ground  particles  which 
gives  the  chief  value  to  the  cement,  the  use  of  separators  on  the  clinker- 
grinding  side  of  a  cement-plant  would  seem  to  be  inadvisable.  In  pul- 
verizing raw  materials  the  same  objection  can  be  made,  though  it  is 
not  so  important  as  in  grinding  the  finished  product. 

The  following  papers  contain  data  on  the  subject  of  separators: 

Eckel,  E.  C.  Some  of  the  reasons  why  separators  are  not  used  in  Portland- 
cement  works.  Engineering  News,  vol.  51,  p.  344.*.  April  7,  1904. 

Fraser,  G.  H.  Recent  results  obtained  with  the  Kent  mill  as  a  fine  grinder. 
Cement,  vol.  6,  pp.  74-79.  May,  1905. 

Humphrey,  R.  L.  The  plant  of  the  Buckhorn  Portland  Cement  Co.  Engi- 
neering News,  vol.  50,  pp.  408-414.  Nov.  5,  1903. 

Michaelis,  W.,  jr.  Air  separation  of  cement.  Cement  and  Engineering  News, 
vol.  15,  p.  2.  Oct.,  1903. 


CHAPTER  XXXV. 
STANDARD  TYPES  OF  CRUSHING  AND    PULVERIZING  MACHINERY 

IT  has  seemed  advisable  to  devote  a  chapter  to  the  description  of 
various  standard  types  of  crushing  and  pulverizing  machinery.  In 
selecting  the  particular  machines  to  be  described  in  this  chapter,  the 
writer  has  attempted  to  include  those,  and  only  those,  which  are  known 
to  him  as  being  in  satisfactory  operation  at  one  or  more  American  cement- 
plants.  It  is  possible  that  in  endeavoring  to  exclude  worthless  types 
some  meritorious  machines  may  have  been  unintentionally  neglected; 
but  it  is  safe  to  say  that  over  95  per  cent  of  the  cement  made  in  this 
country  is  crushed  and  pulverized  by  machines  described  in  the  follow- 
ing pages. 

In  describing  the  various  types  of  crushers  and  pulverizers,  the 
drawings  of  the  mills  and  the  data  relative  to  their  construction  and 
mechanical  operation  have  been  taken  mostly  from  trade  catalogues 
or  from  descriptions  prepared  by  the  manufacturers.  The  data  on 
output,  fineness  and  power  lequired  were,  however,  in  almost  all  cases 
obtained  from  managers  of  cement-mills,  and  are  believed  to  be  entirely 
reliable. 

Classification  of  Grinding  Machinery. 

So  many  types  and  varieties  of  crushing  and  pulverizing  machinery 
are  now  on  the  market  that  it  is  difficult,  from  a  single  description,  to 
form  much  of  an  idea  of  the  relation  of  any  given  one  of  these  machines 
to  any  of  the  others.  To  aid  in  this,  the  machines  described  in  the 
following  pages  have  been  grouped  under  eight  classes,  according  to 
their  general  methods  of  action.  This  grouping  is  as  follows: 
Class  1.  JAW  CRUSHERS;  material  crushed  between  two  jaws  which  approach 

and  recede BLAKE  CRUSHER. 

Class  2.  CONE  GRINDERS  ;  material  crushed  by  the  revolution  of  a  toothed  cone 

or  spindle  within  a  toothed  cup GATES  CRUSHER,  CRACKERS. 

Class  3.  ROLLS;  material  crushed  between  two  or  more  plain,  fluted,  or  toothed 

cylinders  revolving  in  opposite  directions ROLLS. 

429 


430  CEMENTS,  LIMES,  AND  PLASTERS. 

Class  4.  MILLSTONES;    material  crushed  between  two  flat  or  grooved  discs, 

one  of  which  revolves. 

MILLSTONES,  BUHRS,  STURTEVANT  EMERY  MILLS,  CUMMINGS  MILL. 
Class  5.  EDGE-RUNNERS;    material  crushed  in  a  pan,  under  a  cylinder  turning 

on  a  horizontal  axis  and  gyrating  about  a  vertical  axis. 

EDGE-RUNNERS,  DRY-PAN. 
Class  6.  CENTRIFUGAL  GRINDERS;'   material  crushed  between  rollers  and  an 

annular  die,  against  which  the  rollers  are  pressed  by  centrifugal 

force. 

HUNTINGDON  MILL,  GRIFFIN  MILL,  NAROD  MILL,  CLARK  PULVERIZER. 
Class  7.  BALL  GRINDERS;    material  crushed  by  balls  or  p'ebbles  rolling  freely 

in  a  revolving  horizontal  cylinder. 

KOMINUTER,  BALL  MILL,  TUBE  MILL. 

Class  8.  IMPACT  PULVERIZERS;   material  crushed  by  a  blow  in  space  delivered 
by  revolving  hammers,  bars,  cups,  or  cages. 

WILLIAMS  MILL,  RAYMOND  PULVERIZER,  STURTEVANT  DISINTE- 
GRATOR, STEDMAN  DISINTEGRATOR,  CYCLONE  PULVERIZER. 

Class  i.  Jaw  Crushers. 

In  this  familiar  type  of  coarse  crushing  machines,  of  which  the  Blake 
crusher  is  both  the  oldest  and  best-known  representative,  the  material 
is  fed  between  two  powerful  jaws,  and  crushed  by  their  near  approach 
to  each  other.  The  principle  upon  which  these  machines  work  is  well 
adapted  for  breaking  stone,  but  is  not  serviceable  for  finer  reduction. 
The  Blake  crusher  in  its  various  forms,  and  the  Dodge  and  other  de- 
vices of  the  movable-jaw  type,  are  therefore  machines  suitable  for 
first  reduction  only. 

For  detailed  descriptions  of  the  Blake  crusher,  and  of  the  modifi- 
cations in  which  the  same  principle  has  appeared,  reference  should  be 
made  to  the  valuable  paper  cited  below.* 

In  mining  and  metallurgical  practices  jaw  crushers  are  commonly 
used,  but  in  the  cement  industry  they  have  almost  entirely  given  place 
to  the  gyratory  crushers  described  in  the  next  section. 

Class  2.  Cone  Grinders;  Gyratory  Crushers. 

Under  this  heading  are  grouped  the  crushing  machines  in  which 
the  material  is  crushed  between  a  toothed  or  grooved  cone  or  spindle 
and  the  grooved  cup  within  whicK  it  revolves.  The  Gates  crusher, 
the  Mosser  crusher,  and  the  McEntee  and  other  " crackers"  are  here 

*  Blake,  W.  P.  The  Blake  stone  and  ore-breaker:  its  invention,  forms,  and 
modifications,  and  its  importance  in  engineering  industries.  Trans.  Amer.  Inst. 
Mining  Engineers,  1903,  pp.  988-1031. 


CRUSHING  AND  PULVERIZING  MACHINERY. 


431 


included.  The  " crackers'7  have  been  described  quite  fully  on  page 
239,  in  dealing  with  the  crushing  practice  in  natural-cement  plants, 
and  the  Mosser  crusher  is  of  essentially  the  same  design  as  these  crackers, 
though  built  for  heavier  work. 

The  Gates  crusher,  shown  in  view  in  Fig.  87,  and  in  section  in  Fig. 
88;  is  probably  the  most  extensively  used  machine  of  its  type.     In  re- 


FIG.  87. — External  vie\\  of  Gates  crusher. 

gard  to  its  power  requirements,  capacity,  etc.,  its  manufacturers  state: 
"  In  estimating  power  to  drive  our  breakers  we  have  provided 
for  running  an  elevator  and  screen  also.  But  it  must  be  borne  in 
mind  that  no  close  estimate  can  be  made  to  cover  all  sorts  of  rock 
and  ore;  and  further,  it  should  be  observed  -  that  it  requires  much  more 
power  per  ton  to  break  rock  to  J  inch  than  is  required  to  break  it  to 
an  inch.  The  estimates  given  in  Table  176  are  intended  to  cover  the 
ordinary  macadam  breaking.  For  fine  breaking  add  liberally  to  the 
power.  Long  experience  has  demonstrated  the  reliability  of  the  follow- 
ing general  rule,  applicable  to  breaking  the  hardest  rock  to  2^-inch 
ring,  viz.:  The  Gates  breaker  will  not  require  over  one  horse-power 
per  ton  of  rock  broken  per  hour.'' 


432 


CEMENTS,  LIMES,  AND   PLASTERS. 


The  estimate  (see  Table  177)  of  the  cost  of  crushing  with  a  Gates 
crusher  is  based  by  Professor  Richards  on  the  results  of  a  number  of 


FIG.  88. — Sectional  view  of  Gates  crusher. 

The  names  of  the  several  parts  designated   by  numbers  in  the  above  illustration  may  be 
found  in  the  following  table: 

1.  Bottom  plate  11.  Bevel-pinion  24.  Octagon  step 

2.  Bottom  shell  12.  Band-wheel  25.  Main  shaft 

3.  Top  shell  13.   Break-pin  hub  26.  Upper  ring  nut 

4.  Bearing-cap  14.  Break-pin  27.  Lower  ring  nut 

5.  Oil-cellar  cap  15.  Oil-bonnet  28.  Steel  step 

6.  Spider  16.  Dust-ring  .    29.  Lighter  screw 

7.  Hopper  17.  Dust-cap  30.  Lighter  screw,  jam  nut 

8.  Eccentric  18.  Head  31.  Counter-shaft 

9.  Bevel-wheel  19.  Concaves  33.  Oiling-chain 
10.  Wearing-ring  22.  Chilled  wearing-plates 

mill  tests  at  ore-treatment  plants.  As  the  ore  handled  at  these  mills 
was,  in  general,  harder  than  the  raw  materials  used  in  Portland-cement 
manufacture,  allowance  should  be  made  for  this  feature. 


CRUSHING    AND  PULVERIZING  MACHINERY. 


433 


TABLE  176. 
SIZES,  POWER,  ETC.,  OF  GATES  CRUSHERS. 


Dimen- 

Size Engine 

Size. 

Dimen- 
sions of 
Each 
Receiving 
Opening 
Inches. 

Dimen- 
sions of 
Receiving 
Openings 
Combined 
Inches. 

Weight 
of 
Breaker, 
Lbs. 

Capacity  per 
Hour,  in  Tons 
of  2000  Lbs., 
Passing  2i- 
inch  Ring, 
According  to 
Character  of 
Rock  or  Ore. 

Smallest 
Size  Prod- 
uct can 
be  Made 
at  One 
Break, 
Inch. 

sions  of 
Driving- 
pulley, 
Inches. 

evolutions  of 
Driving-pulley. 

Recom- 
mended to 
Drive 
Breaker, 
Elevator, 
and  Screen. 
Indicated 
Horse- 

1 

• 

3 

^ 

fc 

&, 

power. 

F 

2X    6 

2X    12 

650 

a 

8 

2f 

700 

1  to     11 

H 

7X18 

7X    54 

11,800 

8 
1 

24 

*8 

4 

600 

A     LU        -L  ^ 

10         15 

OD 

4X15 

4X   30 

3,550 

2  to      4 

2 

16 

6 

500 

4           5 

ID 

5X18 

5X   36 

5,5CO 

4           8 

| 

20 

7 

475 

8         10 

2D 

6X21 

6X   42 

8,000 

6         12 

1 

24 

8 

450 

12         15 

3D 

7X22 

7X   45 

14,000 

10         20 

H 

28 

10 

425 

20         25 

4D 

8X27 

8X   54 

21,000 

15         30 

32 

12 

400 

25         30 

5D 

10X30 

10  X   60 

30,000 

25        40 

if 

36 

14 

375 

30         40 

6D 

11X36 

11  X    72 

42,000 

30         60 

2 

40 

16 

350 

40         60 

7£D 

14X45 

14  X   90 

63,000 

75       125 

2| 

44 

18 

350 

75       125 

7|K 

14X45 

14  X   90 

67,000 

75       125 

2i 

44 

18 

350 

75       125 

8D 

18X63 

18X126 

94,000 

125       200 

3 

48 

20 

350 

100       150 

8L 

18X63 

18X126 

91,500 

125       200 

3 

48 

20 

350 

100       150 

9K 

21X48 

21  X  144 

155,000 

300       500 

4 

56 

20 

300 

100       150 

TABLE  177. 
ESTIMATED  COST  OF  CRUSHING  BY  GATES  CRUSHER.* 


Number  of  crusher  

0 
4X30 

72 
3 

$375 

0.021 
0.169 
0.541 
5.556 
0.971 
0.308 

2 

6X42 
216 
9 

$760 

Cost  in  Ce 
0.021 
0.114 
0.541 
1.852 
0.971 
0.308 

4 
8X54 
540 
22 
$1800 

;nts  per  Toi 
0.021 
0.108 
0.541 
0.741 
0.971 
0.308 

6 
11X72 
1080 
45 
$3300 

i  Crushed. 
0.021 

0.099 
0.541 
0.370 
0.971 
0.308 

"    8 
18X126 
3000 
125 
$7000 

0.021 
0.076 
0.541 
0.133 
0.971 
0.308 

Size  of  mouth  in  inches  

Tons  crushed  in  twenty-four  hours.  . 
Horse-power  used  

List  price  of  crusher  

Cost  of  oil  

interest  and  depreciation  

'  '     of  power  

"     "  labor.  . 

"  wear  

"     "  repairs  

Total  

7.566 

3.807 

2.678 

2.310 

2.050 

Class  3.  Rolls. 

In  the  group  of  crushing  machines  here  considered  the  material  is 
crushed  between  two  or  more  cylinders  which  revolve  in  opposite  direc- 
tions. These  cylinders  may  be  plain-surfaced,  longitudinally  fluted, 
or  toothed,  according  to  the  character  of  work  they  are  expected  to 
perform.  As  the  fineness  of  the  product  is  regulated  chiefly  by  the 


*  Richards,  R.  H.     Ore  Dressing,  vol.  1,  p.  50.     1903. 


434 


CEMENTS,  LIMES,  AND  PLASTERS. 


FIG.  89. — Elevation  of  rock-crushing  system,  Edison  plant.     (The  Iron  Age.") 


CRUSHING  AND  PULVERIZING  MACHINERY.  435 

closeness  with  which  the  cylinders  are  set,  it  is  obvious  that  we  have  here 
a  type  of  machine  very  different  from  the  jaw  crushers  and  cone  grinders 
previously  discussed,  for  rolls  can  be  used  for  either  coarse  or  fine 
grinding. 

By  far  the  most  extensive  use  of  rolls  in  the  cement  industry  is 
made  at  the  Edison  plant  at  Stewartsville,  N.  J.,  where  all  the  crush- 
ing and  grinding  on  both  the  raw  and  clinker  sides  of  the  mill  is  accom- 
plished hi  rolls.  At  other  plants  rolls  are  used,  if  at  all,  only  for  crush- 
ing clinker,  direct  from  the  kilns,  to  a  size  that  can  be  economically 
handled  by  Griffin,  Huntingdon  or  ball-mills. 


FIG.  90. — View  looking  down  between  5-foot  rolls,  Edison  plant. 
(Engineering  News.) 

At  the  plant  of  the  Edison  Portland  Cement  Company  the  raw 
materials  are  crushed  and  pulverized  in  a  series  of  rolls  of  special  design. 
The  elevation  of  this  series  is  shown  in  Fig.  89,  while  Fig.  90  is  a  view 
looking  downward  on  one  of  the  coarser  sets  of  rolls.  In  Fig.  91  the 
plan  and  elevation  of  the  fine-grinding  rolls  of  the  Edison  plant  are 
presented. 

With  the  exception  of  the  Edison  plant,  however,  rolls  are  rarely 
or  never  used  for  fine  grinding  in  Portland-cement  practice  on  either 
the  raw  or  clinker  sides  of  the  mill.  They  are  commonly  used  in  coal 
crushing,  particularly  when  lump  or  run-of-mine  coal  is  bought  (see 
pp.  514,  515) ;  and  in  many  plants  they  are  used  as  a  first  reducer  on 


436 


CEMENTS,  LIMS,  AND   PLASTERS. 
i^  .,•,«»  * 


4-10 


CRUSHING  AND  PULVERIZING  MACHINERY.  437 

clinker.  For  this  last  purpose  they  are  specially  well  adapted,  because 
they  can  handle  hot  clinker  with  less  injury  than  any  other  form  of  grind- 
ing machinery. 

Class  4.  Millstones. 

This  class  of  crushing  machinery  includes  those  types  in  which  the 
material  is  ground  between  two  flat  or  grooved  discs,  one  of  which 
revolves.  These  discs  are  usually  set  horizontally,  though  they  may 
also  be  arranged  vertically.  The  class  includes  the  millstones  and  buhr- 
stones  proper,  and  several  patented  devices  such  as  the  Sturtevant 
rock-emery  mill  and  the  Cummings  mill.  As  these  machines  are  exten- 
sively used  in  grinding  natural-cement  clinker,  they  have  been  already 
described  under  that  head  (pp.  239-243).  In  Portland-cement  practice 
they  are  now  rarely  used,  though  in  the  old-style  wet-process  plants 
millstones  were  almost  invariably  adopted. 

At  one  small  Portland-cement  plant  seven  runs  of  48-inch  upper- 
runner  French  buhrstones  were  employed  in  taking  J-inch  clinker  from 
the  rolls  and  reducing  it  to  about  20-mesh.  Each  run  of  stones  required 
8  H.P.  and  handled  about  two  barrels  of  clinker  per  hour.  A  sieve 
test  showed  the  following  results: 

Mesh  of  sieve 20         30         50       100 

Per  cent  passed 98         98         92         65 

Per  cent  residue 2  4  8         35 

The  seven  mills  required  about  one  man's  time  for  dressing.  The 
particular  economy  of  the  installation  lay  in  the  fact  that  the  mills 
cost  only  about  $10  per  run,  having  been  purchased  from  old  flour-mill 
plants.  New  mills  of  similar  type  would  cost  about  $250  each. 

Class  5.  Edge-runners. 

The  class  of  edge-runner  mills  includes  those  types  in  which  the 
material  is  crushed  in  a  pan  under  a  cylinder,  the  cylinder  haying  two 
motions — turning  on  itself  on  a  horizontal  axis  and  also  revolving  as 
a  whole  about  a  fixed  vertical  axis.  The  familiar  " dry-pans"  and 
"wet-pans"  of  brick-plants  are  here  included,  a  modern  dry-pan  of 
improved  type  being  shown  in  Fig.  92.  In  the  Portland-cement  indus- 
try, particularly  in  wet-process  plants,  dry-pans  are  much  used  in  grind- 
ing the  clay  or  shale.  Elsewhere  they  are  of  little  service. 

Clay  is  ground  in  a  dry-pan,  at  one  marl-plant,  at  the  rate  of  6  tons 
per  hour,  the  dry-pan  requiring  about  30  H.P.  for  operation.  This 


438  CEMENTS,  LIMES,  AND  PLASTERS. 

power  figure  seems    unusually  high,    for  at  other  plants  the  dry-pan 
doing  similar  work  is  usually  estimated  as  taking  about  15  H.P. 

A  dry-pan  used  on  fairly  hard  shale  at  another  wet-process  cement- 
plant  takes  fragments  up  to  4"XS"  in  size  and  reduces  them  to  about 
8-mesh.  It  requires  about  20  H.P.  and  gives  a  product  of  about  6  tons 
per  hour.  <* 


FIG.  92. — Dry-pan.     (Allis-Chalmers  Co.) 

Class  6.  Centrifugal  Grinders. 

In  the  more  typical  examples  of  this  class  of  mills  the  material 
is  crushed  between  a  horizontal  die  ring  and  one  or  more  vertically 
hung  rollers  which  are  held  against  the  ring  by  centrifugal  force. 
Such  typical  examples  among  cement-grinding  machinery  are  the 
Huntingdon  and  Griffin  mills.  A  somewhat  different  arrangement 
exists  in  the  Kent  mill,  which  is  included  here  for  convenience.  In 
this  mill  the  ring  is  set  vertically  and  the  three  rolls  horizontally.  Only 
one  of  the  rolls  is  positively  driven,  the  other  two  rolls  and  the  ring 
taking  motion  from  the  driven  roll. 

The  .mills  of  this  class  have  been  used  as  one-stage  reducers  at  a 
number  of  cement-plants,  taking  raw  material  or  clinker  in  ^-  to  1-inch 
sizes  and  reducing  it  to  85  to  95  per  cent  through  a  100-mesh  sieve, 
and  they  have  accomplished  this  task  with  a  fair  degree  of  efficiency. 
Of  late  years,  however,  the  tendency  has  been  very  markedly  in  favor 
of  lightening  this  task  by  putting  in  tube  mills  for  the  final  reduction. 

Huntingdon  mill. — The  Huntingdon  mill  as  used  in  the  manufac- 
ture of  Portland  cement  is  a  slightly  modified  form  of  the  mill  of  the 
same  name  used  in  gold-ore  treatment.  The  rights  of  the  Huntingdon 


CRUSHING  AND  PULVERIZING  MACHINERY. 


439 


mill  for  the  cement  industry  are  controlled  by  the  Atlas  Portland 
Cement  Company.  The  mill  has  in  consequence  been  used  only  in 
the  plants  of  that  company,  where  it  seems  to  have  given  good 
satisfaction. 

In  the  Huntingdon  mill  three  heavy  rollers  are  suspended  from 
a  circular  horizontal  head,  the  attachment  being  such  as  to  allow  free 
radial  swing  to  the  rollers.  The  rapid  revolution  of  the  head  causes 
the  rollers  to  diverge,  swinging  outward,  and  being  pressed  by  centrif- 


FIG.  93. — Huntingdon  mills  at  Atlas  plant.     (Atlas  Portland  Cement  Co.) 

ugal  force  against  a  horizontal  annular  die  ring  of  steel.  The  material 
fed  in  is  pulverized  between  this  fixed  ring  and  steel-head  rings  attached 
to  the  bottom  end  of  each  roller.  The  mill,  therefore,  differs  from  the 
Griffin  mill,  chiefly  in  the  fact  that  the  single  roller  of  the  latter  mill 
is  revolved  positively  by  power  applied  directly  to  its  upper  end, 
while  in  the  Huntingdon  mill  the  individual  rollers  are  not  positively 
rotated. 

A  Huntingdon  mill  requires  about  40  H.P.  If  fed  with  material 
varying  from  \  to  1  inch  in  size,  its  output  on  clinker  will  be  about  8 
barrels  per  hour,  ground  so  as  to  pass  92  per  cent  through  a  100-mesh 
sieve.  On  raw  material  its  output  will  vary  from  15  to  25  barrels  per 


440  CEMENTS,  LIMES,  AND  PLASTERS. 

hour,  ground  to  pass  93  per  cent  through  a  100-mesh  sieve.  For  grind- 
ing clinker  to  a  fineness  of  90  or  92  per  cent  on  100-mesh,  the  Hunting- 
don mill  has  given  good  satisfaction,  but  for  the  greater  fineness  now 
required  by  many  specifications,  it  is  probable  that  the  finishing  work 
can  be  done  more  economically  with  the  tube  mill.  The  rate  of  grind- 
ing clinker,  quoted  above,  is  -equivalent  to  an  expenditure  of  5  H.P. 
hours  per  barrel  of  cement,  which  is  about  the  same  as  the  work  done 
by  the  Griffin  mill  under  similar  conditions. 

Griffin  mill. — If  we  disregard  the  enormous  Atla$.  plants,  the  Griffin 
mill  is  by  far  the  most  extensively  used  of  the  class  of  centrifugal  grind- 
ers. It  is  shown  in  section  in  Fig.  94. 

On  reference  to  this  figure  it  will  be  seen  that  the  power  is  received 
by  a  pulley  (17)  running  horizontally.  From  this  pulley  is  suspended 
the  shaft  (1)  by  means  of  a  universal  joint  (9),  and  to  the  lower  ex- 
tremity of  this  shaft  is  rigidly  secured  the  crushing  roll  (31),  which  is 
thus  free  to  swing  in  any  direction  within  the  case.  This  case  consists 
of  the  base,  or  pan  (24),  containing  the  ring,  or  die  (70),  against  which 
the  roll  (31)  works,  and  upon  the  inner  vertical  surface  of  which  the 
pulverizing  is  done. 

In  dry  pulverizing,  this  panx  or  base  (24),  has  a  number  of  openings 
through  it  downward,  outside  of  the  ring,  or  die,  which  lead  into  a  pit, 
or  receptacle,  from  which  it  is  delivered  by  a  conveyor. 

Upon  this  base  is  secured  the  screen  frame  (44),  which  is  surrounded 
with  a  sheet-iron  cover  (45)  (in  the  wet  mill  this  cover  is  not  used), 
and  to  the  top  of  which  is  fastened  a  conical  shield  (25),  open  at  the 
apex,  through  which  the  shaft  works. 

The  cut  shows  the  pulverizing  roll  attached  to  the  lower  end  of  the 
shaft  (1),  and  just  above  the  roll  is  the  fan  (7),  which  is  used  in  the 
dry  mill,  but  not  in  the  wet.  On  the  under  side  of  the  roll  are  shown 
shoes,  or  plows  (5),  which  are  used  in  both,  and  varied  in  shape  accord- 
ing to  the  nature  of  the  work  to  be  done. 

The  pulley  (17)  revolves  upon  the  tapered  and  adjustable  bearing 
(20),  which  is  supported  by  the  frame  composed  of  the  standards  (23). 
Two  of  these  standards  (23a)  are  extended  above  the  pulley  to  carry 
the  arms  (22),  in  which  is  secured  the  hollow  journal  pin  (12). 

Within  the  pulley  is  the  universal  joint  from  which  the  shaft  (1) 
is  suspended.  This  joint  is  composed  of  the  ball,  or  sphere  (9),  with 
trunnions  attached  thereto^  These  trunnions  work  in  half  boxes  (11) 
which  slide  up  and  down  recesses  in  the  pulley-head  casting  (16). 

The  joint  in  the  pulley  is  enclosed  by  means  of  the  cover  (13),  thus 
keeping  the  working  parts  away  from  all  dust  and  grit. 


CRUSHING  AND  PULVERIZING  MACHINERY. 


441 


The  lubricating  oil  is  supplied  for  all  parts  needing  it  through  the 
hollow  pin  (12). 

The  roll  is  revolved  within  the  die  in  the  same  direction  that  the 
shaft  is  driven,  but  when  coming  in  contact  with  the  die  it  travels  around 
the  die  in  the  opposite  direction  from  that  in  which  the  roll  is  revolv- 


16 


17 


FIG.  94. — Section  of  Griffin  mill. 

ing  with  the  shaft,  thus  giving  the  mill  two  direct  actions  on  the  material 
to  be  ground.  There  is  a  pressure  by  centrifugal  force  of  6000  Ibs. 
brought  to  bear  on  the  material  being  pulverized  between  the  roll  and 
die,  the  united  actions  being  very  effective  in  their  combination. 


442 


CEMENTS,  LIMES,  AND  PLASTERS. 


When  a  quantity  of  the  material  to  be  reduced  has  been  fed  into 
the  mill  sufficient  to  fill  the  pan  as  high  as  the  shoes,  or  plows,  on  the 
lower  side  of  the  roll,  they  work  in  it,  stir  it  up,  and  throw  it  against 
the  ring,  so  that  it  is  acted  upon  by  the  roll;  and  when  fairly  in  oper- 
ation the  whole  body  of  loose  material  whirls  around  rapidly  within 
the  pan,  and,  being  brought  between* the  roll  and  die,  is  crushed,  and 
all  that  is  sufficiently  fine  passes  at  once  through  the  screen  above  the 
die,  the  coarser  portion  falling  down  to  be  acted  upon  again. 

The  universal  joint,  by  which  the  shaft  is  connected  with  the  pulley, 
allows  perfect  freedom  of  movement  to  the  roll,  so  that  it  can  safely 
pass  over  pieces  of  iron,  steel,  etc.,  such  as  are  usually  found  in  all 
rock  to  be  pulverized,  without  damage  to  the  mill. 

The  fan  attached  to  the  shaft  above  the  roll  draws  air  in  at  the  top 
of  the  cone,  forcing  it  through  the  screens  and  out  into  the  discharge, 
thus  effectually  keeping  all  dust  within  the  mill. 

In  working  dry  the  screen  which  surrounds  the  pulverizing  chamber 
is  of  much  coarser  mesh  than  the  delivered  product;  for  instance,  a 
16-mesh  screen  delivers  a  product  over  90  per  cent  of  which  will  pass 
a  60-mesh  screen.  Two  sizes  of  the  Griffin  mill  are  made: 

TABLE  178. 
SIZES,  POWER,  ETC.,  OF  GRIFFIN  MILL. 


30-inch  Mill. 

36-inch  Mill. 

Extreme  height  of  mill  above  foundation  
Extreme  width  of  mill 

8  ft.  2J  ins. 
5  "   3     " 

8  ft.  7$  ins. 
6  "    3     " 

Height  from  top  of  foundation  to  center  of  pulley  . 
Weight   complete         

6  "   4$   " 
10,500  Ibs 

6"    6i  " 
14,500  Ibs 

Speed  of  pulley  

190  to  200  rev 

135  to  150  rev 

per  min. 
15  to  25  H  P. 

per  min. 
25  to  30  H.P. 

Diameter  of  pulley 

30  ins 

40  ins 

Diameter  of  roll 

18  to  20  ins 

22  and  24  ins 

Diameter  of  ring  or  die                          .      .  . 

30  ins 

36  ins 

Depth  of  contact  surface  on  roll     .          

6   " 

6   " 

Weight  of  ring  or  die       .        

260  Ibs 

408  Ibs 

Weight  of  tire                   

100  " 

175  " 

Pressure  of  roll  against  die       

6000  " 

8000  " 

When  running  on  clinker  which  has  been  previously  crushed  to  about 
J-inch  size  the  Griffin  mill  will  handle  from  5  to  10  barrels  per  hour, 
using  25  to  30  H.P.  For  clinker-grinding  the  mill  is  usually  equipped 
with  30-  or  32-mesh  screens,  giving  a  product  of  about  95  per  cent 
through  a  100-mesh,  and  70  to  80  per  cent  through  a  200-mesh. 

In  grinding  raw  materials,  24-  or  28-mesh  screens  are  used,  which, 


CRUSHING  AND  PULVERIZING  MACHINERY.  443 

however,  give  a  product  practically  equal  in  fineness  to  the  30-  or  32- 
mesh  screens  used  in  clinker-grinding.  With  these  screens  the  mill 
will  turn  out  2£  to  3  tons  of  raw  material  (equivalent  to  8  to  10  barrels) 
per  hour,  taking  slightly  less  power  than  when  running  on  clinker. 

The  repair  costs  of  a  Griffin  mill  were  stated,  at  a  plant  which  has 
always  used  these  mills  extensively,  to  vary  with  the  material  crushed 
in  about  the  following  ratio: 

Repair  costs  on  clinker  :  repairs  on  raw  mix  :  repairs  on  coal. 
11  :  li  :  1 

Kent  mill. — The  Kent  mill  is  a  comparatively  untried  machine, 
but  deserves  mention  here  because  of  the  favorable  results  reported 
for  it  by  Professor  Newberry,  and  G.  H.  Fraser  (see  p.  468). 

The  Kent  mill  is  shown  in  Fig.  95,  the  casing  being  broken  out, 
and  one  fixed  check-ring  B  being  partly  broken  away  to  show  the  feed 
chutes  A,  the  free  revolving  ring  C,  the  three  crushing-rolls  G,  and  the 
bottom  discharge  outlet  F. 

Referring  to  the  interior  view,  A  is  the  feed-chute;  which  enters 
the  casing  at  opposite  sides  above  one  of  the  three  rolls  G  and  feeds 
into  the  angle  between  this  roll  and  the  ring  C.  The  three  rolls  G  (of 
which  one  is  driven)  are  within  and  support  the  ring  C,  being  drawn 
yieldingly  against  its  concave  inner  face  at  three  points  by  stiff  springs 
acting  against  the  bearing  yokes  carrying  the  shafts  of  the  rolls.  These 
yokes  slide  in  lugs  on  the  casing  and  pull  outward  according  to  the 
adjustment  of  the  springs  by  their  screws.  The  convex  faces  of  the 
rolls  fitting  the  concave  inner  face  of  the  ring  hold  it  in  position  side- 
ways, so  that  the  ring  always  tracks  on  the  rolls,  but  it  is  also  checked 
against  too  much  side  play  by  fixed  check-rings  B  fastened  on  the  inside 
of  the  casing  at  a  slight  distance  from  the  edges  of  the  free  ring,  so  as 
to  leave  a  free  space  D  between  in  which  the  free  ring  can  play  and 
through  which  the  fine  material  may  escape  to  the  discharge  chamber  Ef 
which  surrounds  the  ring  C.  and  at  its  lower  part  meets  the  discharge 
outlet  F.  The  rings  B  are  cut  away  for  a  space  above  the  outlet  F. 
The  fixed  rings  can  be  easily  replaced  if  ever  worn  out. 

In  operation,  the  free  ring  is  cushioned  by  the  rolls  and  held  cen- 
trally, both  axially  and  laterally,  thereby,  but  can  yield  to  pass  a  hard 
substance  or  to  cushion  unequal  thrusts,  and  can  play  sideways  between 
the  fixed  rings  B  to  equalize  variations  of  charge  between  any  roll  and 
the  ring.  The  driven  roll  drives  the  ring  by  contact  with  its  inner 
face,  the  other  rolls  being  passive  and  free  to  revolve  by  contact  with 
the  ring.  The  rolls  and  ring  run  on  each  other  at  like  surface  speeds. 
The  charge  streams  in  between  the  ring  and  one  roll,  passes  the  latter, 


444 


CEMENTS,  LIMES,  AND  PLASTERS. 


and  is  carried  on  the  ring  past  the  other  rolls,  being  held  against  the 
ring  by  centrifugal  force,  due  to  the  speed  of  revolution,  until  the  par- 
ticles are  reduced  to  the  mesh  desired,  when  they  fly  off  of  their  own 
lightness  and  float  inward  and  fall  by  gravitation,  or  pass  outward 
between  the  free  and  fixed  rings,  into  the  chamber  E  and  down  there 


FIG.  95.— Interior  of  Kent  mill. 

through  to  the  outlet  F.  On  entering  the  mill  the  charge  is  set  in 
rapid  revolution  therein,  and  is  kept  revolving  until  all  is  reduced.  This 
action  is  the  same  whether  the  charge  is  great  or  small.  The  charge 
cushions  the  operation  of  the  mill,  the  greater  the  feed  the  less  being 
the  noise  and  vibration. 

Gravity  doors  giving  an  intermittent  feed  close  the  casing  against 
escape  of  dust.  These  open  every  time  the  weight  fed  on  them  is  enough 
to  tilt  them.  The  discharge  flows  out  in  a  large  continuous  stream  of 
the  size  for  which  the  mill  is  adjusted. 


CRUSHING  AND   PULVERIZING  MACHINERY. 


445 


Straight  belts  from  any  shafting,  either  directly  above  or  beneath, 
or  at  any  angle  from  the  mill,  are  run  to  the  pulleys  at  each  end  of  the 
shaft  of  the  driven  roll,  the  speed  required  being  180  to  200  revolutions- 
for  the  driving-pulleys.  No  quartered  belts  are  needed. 


6  ft.  6  ins. 
6" 

6"   6  " 
2  "  9  " 
7500  Ibs. 


Height  of  mill  over  all 

Width  of  mill  over  all 

Length  of  mill  over  all 

Distance  from  floor  to  center  of  driving-pulleys . 

Weight,  complete 

Pulley  speed 180  to  200  rev.  per  min. 

Power  required  (according  to  fineness  and  ma- 
terial)       from  15  to  35  H.P. 

Diameter  of  pulleys 30  or  36  ins. 

Width  of  belts 8  ins. 

Diameter  of  rolls 14    ' ' 

Diameter  of  ring  (inside) 36    lt 

Width  of  contact  surface  on  rolls  and  ring.  ...  7    " 

Weight  of  ring 800  Ibs. 

Pressure  of  each  passive  roll  against  ring 0  to  20,000  Ibs. 

Pressure  of  driven  roll  against  ring 1000  "  21,000   " 

LIST  PRICES. 

Style  F  "Mining"  Mill,  complete,  f.o.b.,  N.  Y . $2500 

"     "         "         '  "     with  separator  and  30-foot  elevator.  .  .  3000 

'•"'.'     "         "           "     crusher,  separator  and  30-foot  elevator  3500 

For  the  following  data  on  the  performance  of  the  Kent  .mill  when 
handling  cement  clinker  in  actual  practice  the  writer  is  indebted  to 
Prof.  S.  B.  Newberry: 

Working  as  an  intermediate  reducer  on  clinker,  taking  it  from  the 
kilns  and  grinding  it  to  20-mesh,  the  Kent  mill  has  given  as  high  as  50 
barrels  per  hour,  taking  24  H.P.  in  doing  so.  Repairs  may  aggregate 
$180  per  year  per  mill.  The  following  table  shows  the  results  of  several 
sieve  tests  of  the  product  from  a  Kent  mill  used  in  this  way  at  a  time 
when  it  was  giving  43J  barrels  cement  per  hour. 


Mesh  of  Sieve. 

Per  Cent  Passing. 

20  
100 

99.5 
53.0 
35.0 

98.5 
49.5 
35.0 

98.0 
48.0 
33.0 

200  

When  used  as  a  one-stage  pulverizer,  taking  clinker  from  the  kilns 
and  reducing  it  to  finished  cement,  a  60-mesh  screen  being  used  on 
the  Columbian  separator,  the  Kent  mill  gave  a  product  of  11.6  barrels 
cement  per  hour.  A  sieve  test  of  this  product  showed  that  97.7  per 


446 


CEMENTS,  LIMES,  AND  PLASTERS. 


CRUSHING  AND   PULVERIZING  MACHINERY. 


447 


cent  of  it  would  pass  a  100-mesh  sieve  and  77.7  per  cent  passed  a  200- 
mesh. 

Class  7.  Ball  Grinders. 

The  mills  of  Class    7  include  all  those  in  which  the  raw  material 
is  ground  by  flint,  iron,  or  steel  balls  rolling  freely  in  a  horizontal  or 


NOTE: 

4"sq.  holes  around  anchor-bolts  to  be  left  open 
imtil  mill  is  adjusted  on  foundation. 


Scale  of  Feefi 


0        12345 


7        8        9        10       11      12       13 

FIG.  97. — Foundation  plan,  Lindhard  kominuter,  No.  66. 

slightly  inclined  revolving  cylinder.  Three  fairly  distinct  types  are 
included  under  this  definition,  examples  of  which  types  are  described 
below  under  the  respective  headings  of  kominuters,  ball  mills,  and  tube 
mills.  Of  these  three  types,  the  kominuter  is  represented  by  only 
one  machine,  the  Lindhard  kominuter;  but  ball  and  tube  mills  are 
made  by  many  manufacturers,  the  different  makes  differing  slightly 
in  design  but  often  greatly  in  value. 


448  CEMENTS,  LIMES,  AND  PLASTERS. 

Kominuter. — The  Lindhard  kominuter,  like  the  ball  mill,  is  a  drum- 
shaped  device,  about  as  high  as  broad,  suspended  by  a  shaft  passing 
through  the  heads  and  resting  on  bearings.  Outside  of  this  drum 
is  a  coarse  perforated  cylindrical  plate,  and  this  in  turn  is  surrounded 
by  a  screen  frame  fitted  with  wire  screening  cloth.  The  material  is  fed 
to  the  kominuter,  as  in  the  ball  mill,  through  an  opening  near  the  shaft 
at  the  head  end  of  the  mill.  It  passes  from  this  to  the  other  end,  being 
ground  meanwhile  by  the  balls,  because  its  only  place  of  exit  is  at  the 
tail  end  of  the  kominuter.  The  discharge  material  passing  thus  out 
of  the  inner  drum,  returns  in  opposite  direction  over  the  perforated 
plates,  the  coarser  particles  being  returned  to  the  inner  drum  by  curved 
pipes.  Of  the  material  which  succeeds  in  passing  the  perforated  plate 
the  finer  particles  go  also  through  the  final  exterior  screen  and  are  sent 
to  the  tube  mills.  The  coarser  particles,  rejected  by  the  exterior  screen, 
are  returned  to  the  inner  drum  by  two  other  curved  pipes. 

This  arrangement,  while  giving  a  regular  and  fine  product,  prevents 
excessive  wear  on  the  wire-cloth  screens,  since  most  of  the  coarser  par- 
ticles do  not  reach  them,  being  rejected  by  the  perforated  plate. 

The  kominuter  was  designed  to  overcome  certain  disadvantages 
which  have  become  apparent  in  machines  of  the  ball-mill  type.  As 
stated  by  the  manufacturers  of  the  kominuter,  the  ball  mill  had  the 
following  defects: 

I.  Insufficient  screen  area  to  prevent  materials  already  ground  fine 
enough  from  returning  to  the  mill  to  be  acted  on  again. 

II.  The  gradual   closing  of    the   holes  in  the  perforated  grinding 
plates  under  the  peening  action  of  the  balls,  resulting  in  a  daily  de- 
crease in  the  output  from  the  ball  mill. 

III.  The  impracticability  of  lining  the  drum  with  the  multiples  of 
a  single  templet  small  enough  to  be  handled  by  one  man;    that  is,  the 
lining  is  either  a  set  of  plates  few  of  which  are  to  the  same  templet  or 
else  a  single  plate  to  each  face  of  the  polygon,  made  so  large  as  to  re- 
quire much  power  to  handle. 

IV.  The  lack  of  means  of  easy  adjustment  to  allow  for  the  widely 
varying  grindability  of  materials,  as  well  as  for  the  desired  fineness. 

The  manufacturers  present  the  following  comparative  statement, 
designed  to  show  the  manner  in  which  these  defects  have  been  overcome 
by  the  kominuter. 


CRUSHING  AND  PULVERIZING  MACHINERY. 


449 


BALL  MILL. 

A  polygon.  Plates,  angles,  bars,  bolts, 
and  rivets  machine-fitted  and  having 
only  the  strength  of  an  angular  construc- 
tion, held  together  with  bolts  and  rivets. 

Perforations  in  the  grinding-plates  ex- 
tend from  inlet  end  to  the  opposite  end, 
and  the  material  escapes  through  these 
throughout  the  whole  length  of  the 
grinding  surface.  The  peening  grad- 
ually closes  these  perforations,  thus  con- 
stantly reducing  the  capacity. 

Injudicious  feeding  will  pack  the  ma- 
terial between  the  perforated  exits  and 
the  screens,  and  stop  the  sieving  action. 
It  is  frequently  necessary  to  remove  the 
screens  to  again  put  the  mill  into  service. 
Choking  damages  the  screens. 


Best  obtainable  information  shows 
about  40  H.P.,  operating  under  normal 
conditions. 

Maximum  charge  4400  to  4500  Ibs. 
Take  the  ball  mill  at  100  per  cent  per 
ton  of  balls. 


The  grinding-plates  form  in  part  the 
support  for  the  screens. 


The  life  of  the  lining  is  governed  bv 
the  nature  of  the  material  ground. 
Eighteen  months  seems  to  be  a  safe 
average. 


As,  however,  the  grinding-plates  form 
a  principal  part  of  the  ball  mill,  the  re- 
lining  of  the  mill  involves  the  discon- 
necting of  many  of  the  main  parts  arid 
takes  a  gang  of  men  several  days.  The 
cost  of  relining  is  further  increased  by 
the  fact  that  the  plates  must  be  partially 
finished,  it  being  only  possible  therefore 
to  use  in  them  material  which  can  be 
readily  machined. 

Since  the  grinding-plates  form  also  the 
supporting  plates,  care  must  be  exer- 
cised not  to  let  them  wear  down  too  far 
or  the  balls  will  fall  through  the  screens 
and  dust  casing. 


A  drum 
boiler. 


KOMINUTER. 

like  a  section  of  a 


steam- 


The  material  travels  from  the  inlet 
end  to  the  opposite  end  across  SOLID 
grinding-plates  and  escapes  through 
large  openings  am 
the  action  of  the  bs 


protected  from 


The  kominuter  can  be  intentionally 
overfed  until  the  screens  are  completely 
choked.  Running  the  kominuter  with- 
out feed  for  20  min.  will  clear  the  screens. 
The  inside  screen  is  usually  coarse  and 
strong.  It  serves  to  limit  the  amount  of 
material  passing  to  the  outside  final 
screen,  and  at  the  same  time  protects 
the  final  screen  from  excessive  wear. 

Operating  under  normal  conditions, 
between  40  and  45  H.P.  With  maxi- 
mum charge  of  balls  and  materials  about 
45. 

Maximum  charge  6600  Ibs. 

The  kominuter  has  given  125  per  cent 
per  ton  of  balls,  as  compared  with  100 
per  cent  from  the  ball  mill,  showing  a 
capacity  of  about  85  per  cent  more  than 
that  of  the  ball  mill. 

The  screen  device  derives  its  support 
wholly  from  the  drum  itself,  and  is  in  no 
way  connected  with  the  grinding  plates 
or  with  any  part  subject  to  heavy  wear. 

The  life  of  the  lining  is  at  least  equal 
to  that  of  the  ball  mill,  but  as  the  komi- 
nuter will  grind  at  least  50  per  cent 
more  than  a  ball  mill  of  equal  size  the- 
wear  per  ton  of  finished  product  is  ob- 
viously very  much  smaller. 

The  relining  of  the  mill  is  done  with 
much  greater  ease  and  at  much  less  cost, 
as  all  plates  can  be  handled  by  one  man 
and  merely  passed  through  the  manhole, 
no  disconnecting  of  the  principal  parts, 
of  the  mill  being  necessary. 


The  grinding-plates  are  not  machined, 
which  reduces  the  cost  and  permits  the 
use  in  the  plates  of  the  material  best 
suited  for  the  purpose,  irrespective  of  its- 
suitability  for  machining. 

Since  the  drum  itself  forms  the  sup- 
porting plate,  the  grinding  plates  can  be 
worn  out  completely  Consequently  very 
little  metal  is  thrown  away  in  the  re- 
placement of  a  lining. 


450 


CEMENTS,  LIMES,  AND  PLASTERS, 


BALL  MILL. 

Rejected  materials  return  to  the  mill 
by  gravity  through  perforated  plates  at 
each  angle  of  the  polygon.  These  plates 
extend  the  length  of  the  mill.  Assuming 
one  third  of  the  interior  area  to  be  cov- 
ered with  balls  and  material,  this  pro- 
portion of  the  return  plates  is  of 'course 
under  an  outward  pressure.  Another 
third  of  the  interior  area  is  moving  up- 
ward, and  through  this  portion  alone 
the  rejected  material  must  pass  back 
into  the  mill.  As  the  remaining  third  is 
moving  downward,  a  portion  of  the  ma- 
terial may  move  downward  with  it  and 
thus  remain  on  the  screen.  Consequently 
a  considerable  proportion  of  rejected  ma- 
terial is  carried  around  indefinitely  at 
the  periphery.  If  the  mill  is  overfed, 
the  insufficiency  of  the  return  openings 
results  in  choking  the  screens  and  limit- 
ing, if  not  altogether  stopping,  the  screen 
action. 

The  discharge  area  in  the  ball  mill  is 
limited  by  the  size  and  number  of 
the  holes  in  the  perforated  grinding- 
plates.  The  ball  mill  is  not  supplied  with 
means  for  enlarging  or  reducing  this  dis- 
charge area.  If  the  ball  mill  is  fed  with 
a  material  relatively  fine  and  difficult  of 
reduction,  too  large  an  amount  will  pass 
the  perforations,  overloading  the  screens 
and  leaving  too  little  material  in  the 
drum  to  be  acted  upon  by  the  balls. 
Here  the  exit  area  is  too  large,  and  it 
cannot  be  readily  reduced.  On  the  other 
hand,  if  the  ball  mill  is  fed  with  a  ma- 
terial easy  of  reduction,  the  balls  will 
reduce  more  than  the  perforations  and 
sieves  can  pass,  resulting  in  an  accumu- 
lation of  an  excess  of  finished  material 
in  the  grinding-drum.  Here  the  dis- 
charge area  is  too  small,  and  it  cannot 
be  enlarged. 

A  very  large  percentage  of  material 
which  passes  through  the  perforated 
grinding-plates  has  been  ground  small 
enough  to  pass  the  screens,  but  owing 
to  the  limited  screen  area  it  is  returned 
to  the  mill  and  the  power  for  regrind- 
ing  is  wasted.  Twenty  to  twenty-five 
per  cent  of  the  material  is  thus  reground 
unnecessarily. 


KOMINUTER. 

All  materials  fed  to  the  kominuter 
must  pass  the  full  length  of  the  drum 
under  the  grinding  action  of  the  balls, 
and  is  discharged  through  ports  at  the 
outlet  end.  The  conical  shape  of  the 
screens  forces  the  material  to  move  from 
vihe  outlet  end  back  to  the  inlet  end, 
Hvhere  the  material  rejected  by  the 
screens  is  caught  by  return  buckets  and 
returned  to  the  inlet  end  of  the  drum 
by  gravity.  The  buckets  empty  at  the 
center  of  the  mill  around  the  shaft  and 
above  the  level  of  the  balls.  It  will  thus 
be  seen  that  it  is  impossible  for  any  of 
the  material  to  reenter  the  screens  with- 
out repassing  the  grinding  chamber,  as 
may  easily  happen  in  the  ball  mill. 


On  the  kominuter  adjustments  of  the 
feed,  of  the  discharge  ports,  and  of  the 
screens,  are  easily  and  quickly  made. 
The  total  area  of  the  discharge  ports  is 
greater  than  is  required  by  the  maxi- 
mum charge  of  balls.  It  is  an  easy  mat- 
ter to  insert  a  sufficient  number  of  port 
closers,  or  covers,  to  allow  the  discharge 
of  only  sufficient  material  to  utilize  the 
extreme  capacity  of  the  sieves.  With 
these  three  adjustments,  the  highest 
possible  efficiency  upon  a  given  material 
may  be  promptly  and  easily  secured. 


The  material  discharged  from  the 
grinding-drum  must  pass  over  screens 
extending  from  the  outlet  end  to  the  in- 
let end.  The  material  refused  by  the 
screen  in  this  travel  is  automatically  re- 
turned to  the  inlet  end  of  the  drum. 
About  one  half  of  one  per  cent  only  of 
such  returned  material  would  have  passed 
the  screen. 


A  kominuter  running  on  raw  mix — a  fairly  soft,  shaly  limestone — 
gave  a  product  of  15,046  Ibs.  per  hour.  The  feed  was  coarse,  varying 
from  4  inches  down  to  dust,  and  would  probably  average  1J  inches. 
The  product  gave  the  following  sieve  test: 


CRUSHING  AND   PULVERIZING  MACHINERY. 


451 


Mesh  of  Sieve. 

Per  Cent 
Passing. 

Per  Cent 
Residue. 

10 

99.5 

0.5 

20 

95.0 

5.0 

30 

75.5 

24.5 

50 

57.5 

42.5 

80 

45.5 

54.5 

100 

43.5 

56.5 

Working  on  Lehigh  district  raw  material,  a  kominuter  has  given 
over  14,000  Ibs.  per  hour.  On  a  harder  mix,  at  a  plant  in  the  middle 
west,  a  kominuter  gave  13,812  Ibs.  per  hour. 


FIG.  98. — Exterior  view  of  kominuter.     (F.  L.  Smidth  &  Co.) 

A  kominuter  running  on  a  mixture  of  limestone  and  shale,  of  which 
the  limestone  had  been  passed  through  a  crusher  to,  say,  1  inch,  and  the 
shale  through  a  disintegrator,  reduced  about  18,000  Ibs.  per  hour.  The 
product  on  a  number  of  sieve  tests  gave  the  following  residues  on  a 
100-mesh  sieve: 


54.5%,  55.2%,  59%,  52.4%,  43%,  45%. 


452 


CEMENTS,  LIMES,  AND  PLASTERS. 


A  test  run  on  clinker  of  a  kominuter  recently  installed  gave  a 
product  of  60  barrels  per  hour.  The  kominuter  was  fitted  with  14- 
mesh  screen  and  the  product  gave  a  residue  of  55  per  cent  on  a  50-mesh 
sieve. 

Another  plant  using  fresh  clinker  got  a  product  of  35.3  bbls.  per 
hour  from  one  kominuter.  This  product  gave  the  following  results  on 
a  sieve  test: 


Mesh  ot  Sieve. 

Per  Cent 
Passing. 

Per  Cent 
Residue.  ^ 

20 

95.5 

4.5 

50 

56.6 

43.4 

100 

31.3 

68.7 

200 

20.0 

80.0 

At  a  third  plant  clinker  averaging  J-inch  size  was  handled  by  the 
kominuter  at  the  rate  of  15,114  Ibs.  per  hour.  The  product  gave  the 
following  sieve  results: 


Mesh  of  Sieve. 

Per  Cent 
Passing. 

Per  Cent 
Residue. 

10 

99.5 

0.5 

20 

95.0 

5.0 

30 

72.5 

27.5 

50 

50.5 

49.5 

80 

37.5 

62.5 

100 

34.5 

65.5 

Ball  mills. — Ball  mills  are  now  made  by  a  number  of  manufacturers, 
the  types  most  commonly  found  at  the  Portland-cement  industry  being 
the  Smidth,  Gates,  and  Krupp,  and  in  wet-process  plants,  the  Bonnot. 
Of  these  the  Smidth  ball  mill  is  being  gradually  replaced  by  the  Lind- 
hard  kominuter,  and  is  now  recommended  by  its  manufacturers  only 
for  coal-grinding.  It  will  therefore  be  omitted  here  and  described  on 
pages  516-519. 

The  wear  of  steel  balls  in  ball  mills  working  on  clinker  will  vary 
usually  between  the  limits  of  TV  and  ^  Ib.  per  barrel  cement.  As  the 
balls  at  eastern  points  cost  about  $120  per  ton,  the  cost  per  barrel 
will  therefore  range  between  J  and  ^  cent. 

Gates  ball  mill. — This  mill  is  described  by  its  makers  as  follows: 

"The  Gates  ball  mill  consists  of  two  circular  side   plates  provided 

with  inwardly  projecting  and  eccentrically  located  shelves.     The  side 

plates  have  rigidly  attached  to  them  at  their  centers  hubs  which  are 

mounted  on  a  heavy  shaft  which  revolves  in  dust-proof  bearings.     One 


CRUSHING  AND  PULVERIZING  MACHINERY. 


453 


of  the  hubs  has  suitable  openings  through  which  the  material  is  auto- 
matically fed  by  the  Gates  patent  feeder. 

"Resting  on  the  inwardly  projecting  shelves  and  reaching  from 
one  side  plate  to  the  other  and  bolted  thereto  are  the  wearing-plates. 
These  are  eccentrically  arranged  so  that  one  plate  passes  behind  the 
next  one,  thus  producing  a  step  and  also  providing  an  opening  through 


FIG.  99. — Gates  ball  mill  with  feeder  attached  (Allis-Chalmers  Co.),  showing  grind- 
ing-plates  in  position  and  all  other  screws  removed. 

which  residues  from  the  screens  are  returned  to  the  mill.  The  tum- 
bling of  balls  and  material  due  to  revolving  the  drum  rapidly  reduces 
the  material  to  fine  grit  and  powder,  the  steps  serving  to  greatly  in- 
crease the  beating  action  of  the  balls  against  the  material. 

"When  partially  reduced,  the  ground  product  falls  through  aper- 
tures in  the  wearing-plates  onto  the  first  screen.  The  rejections  from 
this  screen  are  promptly  returned  to  mill  through  the  openings  between 
the  overlapping  plates;  the  screened  material  falls  upon  the  second 
screen  and  the  rejections  from  it  are  likewise  returned  to  mill,  while 
the  fines  go  to  the  outside  finishing  screen,  and  what  passes  through 
falls  into  the  dust-proof  housing  and  is  removed  by  conveyor  or  other 


454 


CEMENTS,  LIMES,  AND   PLASTERS. 


means  for  final  pulverization;  the  residues  join  those  of  the  other  screens 
and  with  them  are  returned  to  the  mill  and  subjected  to  further  grind- 
ing action  of  the  balls  until  fine  enough  to  pass  the  outside  or  finishing 


screen. 


FIG.  100. — Transverse  section  of  Gates  ball  mill.     (Allis-Chalmers  Co.) 

TABLE  179. 
SIZES,  WEIGHTS,  ETC.,  OF  GATES  BALL  MILLS. 


Size, 
Numbers. 

Weight  without 
Charge  Balls. 

Weight  Charge 
of  Balls. 

Capacity  on  Portland- 
cement  Clinker  to  20-Mesh. 

Power 
Required. 

7 

29,500  Ibs. 

3000  Ibs. 

12  to  16  bbls.  per  hour 

30  to  40 

8 

41,100  " 

4500    " 

18  to  24    "       "      " 

40  to  50 

NOTE. — From  100  to  120  per  cent  additional  power  is  required  momentarily 
in  starting  the  above  machines.  When  pulverizing  to  pass  all  through  20-mesb 
from  30  to  40  per  cent  will  pass  a  100-mesh  sieve. 


CRUSHING  AND  PULVERIZING  MACHINERY.  455 

Krupp  ball  mill. — This- mill  is  described  as  follows  by  its  agents: 

"The  Krupp  ball  mills  are  made  in  twelve  different  sizes,  but  for 
cement  purposes  in  this  country  the  size  known  as  No.  8  has  been  uni- 
formly adopted. 

"The  mill  comprises  essentially  a  cylindrical  grinding-drum  mounted 
on  a  hammered  steel  shaft  running  through  it  and  provided  with  a  dust- 
proof  sheet-iron  casing.  The  main  shaft  is  carried  on  bearings  secured 
to  heavy  bedplates  bolted  to  a  masonry  foundation.  The  grinding- 
drum  is  composed  of  overlapping  cast-steel  plates  (grinding-plates). 
The  sides  or  head-walls  of  the  drum  are  of  wrought  iron,  secured  to 
the  main  shaft  by  means  of  naves  and  lined  with  steel  side-plates. 

"The  grinding-plates  are  strengthened  on  one  half  and  bent  inwards, 
and  in  the  other  half  holes  are  bored  and  a  series  of  blades  or  scoops 
(return  scoops)  of  sheet  iron,  directed  outwards,  is  provided.  At  those 
places  where  the  scoops  overlap,  channels  are  left  extending  right 
across  the  whole  breadth  of  the  drum  and  partly  stopped  by  low  pro- 
tection sieves  arranged  radially  on  the  scoops. 

"  The  drum  is  surrounded  externally  by  a  fine  cylindrical  sieve  located 
at  a  certain  distance  from  the  grinding-plates.  This  sieve  is  constructed 
of  a  number  of  frames  connected  together  and  secured  to  angle-iron 
rings,  forming  the  outside  limit  of  the  sides  of  the  drum. 

"  The  sieve  frames  are  supplied  in  wrought  iron.  The  sieves  are 
covered  by  a  phosphor-bronze  or  steel-wire  gauze;  the  mesh  is  adapted 
to  the  required  degree  of  fineness  of  the  product  desired. 

"To  protect  the  fine  sieves,  a  coarse  inner  or  fore  sieve  is  arranged 
between  the  outer  sieve  and  the  grinding-plates.  This  inner  sieve  is 
constructed  of  finely  perforated  steel  plates  secured  to  the  lateral  flangeb 
of  the  grinding-plates  and  to  the  back  of  the  scoops;  in  front  of  the 
latter  and  across  the  whole  breadth  of  the  drum  apertures  are  left. 

"  The  drum  contains  a  charge  of  Krupp  special  forged  steel  balls  of 
various  sizes  and  of  a  certain  specified  weight. 

"The  material  is  fed  into  the  drum  through  a  hopper  secured  to  the 
nave  at  the  front  end  of  the  drum.  The  nave  itself  is  designed  so  as 
to  form  two  peculiar  slanting  spokes  which  act  as  a  screw  conveyor 
and  prevent  the  balls  from  being  thrown  out  of  the  mill. 

"  The  lower  part  of  dust  casing  of  the  mill  serves  also  for  collection 
and  discharge  of  the  product  ground  and  is  provided  with  an  outlet 
closed  by  a  slide. 

"In  the  larger  mills  a  rectangular  aperture  is  provided  at  the  top 
of  the  dust  casing  for  the  purpose  of  connecting  the  mill  with  an  air- 
shaft  arranged  above.  The  connection  is  made  by  means  of  a  canvas 


456 


CEMENTS,  LIMES,  AND   PLASTERS. 


hose  secured  to  the  dust  casing  by  a  wooden  frame  and  clamping-screws. 
The  current  of  air  created  in  the  shaft  carries  off  the  moist  vapors 
.arising  during  the  grinding  process,  prevents  dust  flying  from  the  feed- 
hopper,  and  likewise  prevents  the  mill  and  material  being  ground  from 
becoming  unduly  warm.  In  order  that  the  current  of  air  may  be  regu- 
lated according  to  the  weather  it  is  Advisable  to  fit  a  damper  in  the 
shaft. 


FIG.  101. — Automatic  ball-mill  feeder.     (Smidth  &  Co.) 

"  Those  parts  of  the  mill  which  are  subject  to  wear  and  tear,  i.e.,  the 
balls,  grinding,  and  side-plates,  are  made  of  extremely  resistant  well- 
tested  material,  so  that  the  wear  and  tear  is  reduced  to  a  minimum. 

"The  various  parts  of  the  mill  may  be  readily  renewed.  For  this 
purpose  a  manhole  closed  by  a  wrought-iron  cover  is  provided  in  the 
side  of  the  drum  opposite  to  the  hopper,  so.  as  to  admit  of  easy  access 
to  the  interior. 


CRUSHING  AND   PULVERIZING  MACHINERY. 


457 


"The  No.  8  mill  will  take  pieces  up  to  6  inches  in  diameter,  but  the 
feeding  device  usually  used  is  designed  to  take  material  up  to  2J  inches 
only,  which  is  as  large  as  required  for  cement  purposes  in  this  country. 

"In  grinding,  the  balls  in  consequence  of  the  peculiar  arrangement 
of  the  grinding-plates,  on  rotation  of  the  drum  not  only  fall  on  the  plate 
and  roll  forwards,  but  also  fall  over  one  another,  whereby  the  mate- 
rial is  rapidly  broken  up  and  finely  crushed.  After  being  thus  ground 
for  a  sufficient  time,  the  material  falls  through  the  apertures  of  the 
grinding-plates  onto  the  inner  or  fore  sieves,  from  this  onto  the  fine 
sieves  and  through  this  finally,  completely  ground,  into  the  lower  part 
of  the  dust  casing,  whence  it  is  discharged  through  the  outlet.  The 
material  not  yet  sufficiently  ground,  and  retained  by  the  inner  or  the 
fine  sieve  is  carried  back  by  the  return  scoops  into  the  drum  for  further 
grinding.  This  method  of  working  gives  rise  to  very  little  dust,  as 
the  material  being  ground  as  soon  as  it  is  sufficiently  finely  crushed, 
is  immediately  discharged  automatically." 

A  Krupp  5'X21'  ball  mill,  run  on  J-inch  clinker,  gave  a  product 
of  7914  Ibs.  per  hour.  This  product  showed  sieve  results  as  follows: 


Mesh  of  Sieve. 

Per  Cent 
Passing. 

Per  Cent 
Residue. 

10 

100.0 

0.0 

20 

99.5 

0,5 

30 

84.5 

15.5 

50 

57.0 

43.0 

80 

39.0 

61.0 

100 

36.0 

64.0 

Tube  mills. — Unlike  the  ball  mill,  the  tube  mill  has  been  an  unquali- 
fied success  as  a  fine  grinder.  Several  manufacturers  have  placed  these 
mills  on  the  market,  those  most  generally  used  being  the  Davidsen 
(F.  L.  Smidth  &  Co.),  the  Gates  (Allis-Chalmers  Company),  the  Krupp, 
and  the  Bonnot.  The  latter  is  rarely  used  in  dry-process  plants,  but 
is  common  in  wet  plants. 

The  following  description  of  the  tube  mill,  published  by  the  manu- 
facturers of  the  Davidsen  type,  contains  much  of  interest  on  the  group 
in  general. 

"Davidsen  tube  mill. — The  tube  mill  is  simple,  effective,  and  eco- 
nomical in  both  operation  and  maintenance.  It  consists  of  a  wrought 
tube  mounted  as  a  shaft  by  the  attachment  of  dome-shaped  ends  so 
formed  as  to  make  shafts,  which  rest  in  bearings  at  both  ends.  A  large 
gear  attached  to  the  tube  and  a  pinion  attached  to  the  pulley-shaft 
make  the  actuating  device.  The  tube  is  lined  with  stone  or  chilled 


458  CEMENTS,  LIMES,  AND  PLASTERS. 

iron,  as  may  be  required,  and  the  tube  is  about  one-half  filled  with  flint 
balls.  The  enormous  grinding  surface  thus  provided  permits  of  a  very 
slow  speed  of  operation — 27  turns  per  minute.  The  shaft  at  the  feed 
end  is  hollow  and  a  screw  conveyor  carries  in  the  material.  By  simply 
regulating  the  feed  any  degree  of  fineness,  even  to  impalpable  powder, 
may  be  attained.  ^ 

"  Careful  experiments  have  proved  that  for  coarse  grinding  in  a  non- 
continuous  mill,  such  as  an  Alsing  drum,  the  highest  efficiency  is  obtained 
from  a  charge  consisting  of  a  large  mass  of  the  material  to  be  ground 
with  a  relatively  small  amount  of  flint  balls,  and  that  the  highest  effi- 
ciency in  fine  grinding  results  from  the  charge  of  a  small  mass  with  a 


FIG.  102. — Gates  tube  mill.     (Allis-Chalmers  Co.) 

large  number  of  flint  balls.  Take,  for  example,  a  charge  in  the  Alsing 
drum  of  a  small  proportion  of  balls  to  a  large  proportion  of  material. 
Up  to  a  certain  degree  of  coarseness  the  grinding  will  proceed  rapidly 
with  such  a  charge,  but  beyond  that  point  to  secure  a  high  degree  of 
fineness  would  require  a  proportionately  very  much  longer  working  of 
the  materials.  Consequently  any  non-continuous  working  machine 
for  pulverizing  material  is  both  unsatisfactory  and  expensive. 

"  In  the  tube  mill  this  principle  has  been  taken  advantage  of;  the 
flint  balls  bear  a  progressive  ratio  to  the  mass  of  material  best  adapted 
to  the  conditions  demonstrated  in  the  original  experiments. 

"The  material  to  be  ground  is  fed  in  at  the  center  of  one  end  of 
the  tube  mill,  and  is  delivered,  ground,  at  the  periphery  of  the  other 
end.  The  material  consequently  travels  in  a  vertical  line  from  the 
center  to  the  circumference  of  the  mill,  and  in  a  horizontal  line  from 
one  end  to  the  other.  The  tube  mill  being  mounted  horizontally,  a 


CRUSHING  AND  PULVERIZING  MACHINERY.  459 

longitudinal  section,  if  taken  when  the  mill  is  at  rest,  would  show  the 
material  in  the  shape  of  an  acute-angled  triangle,  with  point  at  delivery 
end  and  base  at  the  inlet;  the  transverse  section  at  the  inlet  will,  there- 
fore, show  a  large  amount  of  material  to  a  small  amount  of  flint  balls, 
and  a  transverse  section  at  outlet  end  would  show  the  mill  half  full  of 
flint  balls,  with  but  a  small  amount  of  material  extremely  finely  ground. 
Between  these  two  points  there  is  a  progressive  disposition  of  the  balls 
and  material,  but  at  the  same  time  the  flint  balls  are  evenly  distributed 
throughout  the  tube.  Applying  the  principle  enunciated  above  it  will 
be  seen  that  the  coarse  grinding  is  accomplished  where  the  proportion 
of  material  is  great  in  relation  to  the  flint  balls,  and  that  the  mere  fact 
of  delivery  at  the  periphery  of  the  other  end  compels  an  automatic 
and  gradual  adjustment  of  relations  between  balls  and  materials,  so  that 
at  the  delivery  end  a  transverse  section  would  show  the  mill  half  filled 
with  balls  with  but  a  small  portion  of  material  subject  to  the  grinding 
action. 

"  The  speed  at  which  the  tube  revolves  tends  to  carry  the  mixture  of 
balls  and  material  to  a  certain  height  in  the  mill  from  which  point  balls 
and  material  fall  together  rolling  and  grinding  as  they  seek  the  bottom 
of  the  mill;  the  action  might  be  likened  to  the  action  of  water  at  the 
crest  of  a  wave.  This  sort  of  action  can  only  take  place  when  the  mill 
has  been  half  filled  with  the  flint  balls;  if  less  than  a  proper  charge  of 
flint  balls  is  used  the  whole  mass  has  an  inclination  to  only  slide  upon 
the  inner  surface  of  the  tube,  and  none  of  the  turbulent  wave-crest 
action  suggested  takes  place.  Of  course,  much  the  best  grinding  is 
accomplished  through  keeping  the  whole  mass  of  material  grinding  and 
pounding. 

"The  tube  is  lined  with  iron,  specially  made  tiles,  or  a  natural  stone 
which  we  have  named  'Silex.'  These  are  set  with  Diamond  cement 
made  only  for  this  purpose.  Any  bricklayer  can  readily  lay  up  a  lining. 

"The  life  of  a  lining  depends  upon  the  character  of  the  materials 
ground  on  it.  With  ordinary  care  all  linings  should  last  at  least  a 
year.  In  most  cases  linings  have  served  eighteen  and  twenty-four 
months.  Experience  with  Silex  indicates  that  it  will  serve  two  or 
three  years  of  continuous  grinding. 

"Experiment  has  proven  that  for  grinding,  flint  balls  are  positively 
the  most  economical  medium.  The  tube  mill  has  therefore  been  de- 
signed for  and  proportioned  for  the  use  of  flint  balls. 

"The  tube  mill  for  grinding  slurry  or  wet  materials  is  designed  to 
use  steel  balls  instead  of  flints,  and  is  proportionately  heavier  in  con- 
struction. 


460  CEMENTS,  LIMES,  AND  PLASTERS. 

"It  is  absolutely  necessary  that  the  tube  mill  should  be  filled  up 
to  the  center  line  with  the  flint  balls;  there  is,  consequently,  no  interior 
shaft.  The  tube  revolves  upon  stub  shafts,  which  are  firmly  anchored 
to  the  dome-shaped  ends,  the  one  at  the  inlet  end  being  hollow,  and 
through  which  the  material  is  fed. 

"The  fact  that  flint  balls  in  a  tube,  mill  represent  an  extraordinarily 
large  grinding  surface,  makes  it  possible  to  run  the  mill  at  a  slow  speed 
so  that  all  the  power  required  is  actually  made  use  of  in  the  grinding 
process  itself  and  nothing  is  wasted  in  maintaining  a  high  speed  of  ma- 
chinery, which  effects  nothing  in  the  grinding  process  itself. 

"The  fineness  of  the  output  is  regulated  by  the  speed  at  which  the 
material  is  fed  into  the  machine.  As  every  particle  of  the  material  fed 
must  pass  under  the  grinding  action  of  the  entire  charge  of  balls,  a  thor- 
ough and  uniform  grinding  is  bound  to  be  the  result ;  in  fact,  in  practice 
it  is  found  that  the  uniformity  of  the  output  is  so  great  that  it  is  unneces- 
sary that  sieves  should  be  used,  and  no  provision  is  made  in  the  machine 
by  which  they  can  be  used.  There  is,  of  course,  nothing  to  prevent  the 
materials  being  sieved,  if  it  is  desired,  but  this  is  absolutley  useless  when 
there  is  regularity  of  feeding.  At  a  slow  rate  of  feeding  any  required 
fineness  can  be  obtained  with  any  grindable  material.  The  requirements 
for  grinding  Portland-cement  clinkers  are  ordinarily  that  no  more  than 
12  to  15  per  cent  residue  shall  be  caught  on  a  No.  200  sieve;  when  the 
tube  mill  is  fed  with  coarsely  ground  product  it  will  turn  out  from  8  to 
16  barrels  per  hour  of  Portland-cement  ground  to  the  required  fineness. 
However,  these  figures  do  not  represent  fully  the  value  of  the  grinding 
capacity  of  the  tube  mill.  Careful  scientific  investigation  has  proved 
that  the  fine  product  from  the  tube  mill,  which  will  pass  sieve  No.  200, 
contains  50  per  cent  more  overfine  particles  than  is  the  case  in  the  out- 
put from  any  other  existing  grinding-machine. 

"The  foundation  may  consist  of  any  material  which 'will  support 
the  dead  weight  and  enable  the  journals  to  be  held  firmly  enough  to 
withstand  the  tension  of  the  driving-belt.  In  practice,  however,  it  is, 
of  course,  preferable  that  the  pedestal  foundations  should  be  deep 
enough  in  the  earth  to  resist  the  action  of  frost,  and  should  be  made 
of  permanent  material,  such  as  brick,  stone  or  concrete. 

"In  the  matter  of  repairs  in  this  machine,  as  in  others,  the  advan- 
tage of  slow  speed  over  high  speed  is  practically  noticeable.  This  prin- 
cipal wear  is,  of  course,  upon  the  flint  balls,  and  by  merely  dropping 
in  a  few  at  stated  intervals,  to  maintain  the  charge  at  its  original  bulk, 
the  principal  results  of  wear  are  made  good  at  once. 

"The  flint  balls,  or  pebbles,  are  a  natural  product;   they  are  found 


CRUSHING  AND  PULVERIZING  MACHINERY 


462  CEMENTS,  LIMES,  AND  PLASTERS. 

in  certain  parts  of  Europe  and  are  comparatively  inexpensive  and  of 
extraordinary  hardness.  It  is  the  combination  of  these  qualities  that 
makes  them  preferable  to"  the  steel  balls,  even  to  the  extent  of  building 
the  mill  four  times  as  large  as  would  be  required  with  the  steel  balls. 
These  flint  balls  are  sold  in  four  different  sizes.  The  mill  is  originally 
charged  with  all  four  sizes  -  in  a  set  ^proportion,  but  replacements  are 
always  made  with  the  largest  size,  as  in  practice  the  smaller  pebbles 
seek  the  outlet  end,  and  replacements  are  made  at  the  inlet  end. 

"On  average  Portland-cement  clinker  the  pebbles  wear  at  the  rate 
of  about  1  Ib.  to  30  barrels  of  product. 

"Little  or  no  harm  follows  the  introduction  into  the  mill  of  sub- 
stances foreign  to  the  intended  supply,  such  as  steel  or  iron.  When 
such  substances  reach  the  interior  of  the  mill  they  either  become  grind- 
ing mediums  and  remain  in  the  mill  to  accomplish  that  work,  or  else 
they  are  ground  by  the  action  of  the  mill  and  pass  out  with  the  product. 
This  result  is  so  unlike  that  following  the  introduction  by  accident  of 
a  piece  of  hard  material  into  crushers,  rollers,  buhrstones  or  like  ma- 
chines, where  the  grinding  surface  is  of  metal,  emery  or  dressed  stone, 
that  this  one  fact  recommends  it  promptly  to  the  observing  purchaser. 

"Two  sizes  of  the  Davids  en  tube  mill  are  made: 

"No.  16.  Requires  60  H.P.  and  a  floor  space  of  36  feet  by  13  feet, 
and  turns  25  revolutions  per  minute. 

"No.  12.  Requires  27  H.P.  and  a  floor  space  of  29  feet  by  11  feet, 
and  turns  27  revolutions  per  minute. 

"The  tube  mill  is  a  pulverizer,  not  a  coarse  grinder. 

"The  ' ' grindability'  of  materials,  even  of  the  same  class,  varies  so 
widely  that  it  is  impossible  to  give  more  than  a  general  idea  of  the  ca- 
pacity of  the  tube  mill.  As  an  index,  however,  it  may  be  stated  that 
the  No.  12  tube  mill  will  pulverize  from  3500  to  6500  Ibs.  of  Port- 
land-cement clinker  per  hour,  95  per  cent  of  which  will  pass  10,000  meshes 
per  square  inch,  such  clinker  having  been  preliminarily  ground  to  pass 
No.  20  or  No.  30  sieve. 

"The  No.  16  has  about  two  and  one  quarter  times  the  capacity  of 
the  No.  12." 

Krupp  tube  mill. — The  Krupp  tube  mill  is  described  by  its  agents 
as  follows: 

"The  Krupp  tube  mill  is  a  cylinder  or  drum  5  feet  in  internal  diam- 
eter and  22  feet  long  between  the  heads  of  the  mill.  This  mill  is  so 
designed  as  to  admit  either  silex  or  iron  lining  being  installed. 

"The  feeding  mechanism,  the  most  accessible  and  most  easily  ad- 
justed feeder  on  the  market,  is  so  designed  that  in  making  a  change 


CRUSHING  AND  PULVERIZING  MACHINERY.  463 

neither  the  mill  nor  the  feeding  mechanism  is  stopped  so  that  an  abso- 
lutely uninterrupted  grinding  action  takes  place.  The  main  trunnion 
bearings  are  so  designed  as  to  admit  of  their  being  rebabbitted  with 
the  least  possible  lost  of  time  and  amount  of  labor. 

"The  mill  is  driven  by  means  of  a  split-spur  gear  and  pinion,  the 
former  being  just  scant  of  10  feet  in  outside  diameter.  The  discharge 
device  is  the  Krupp  patent  cone  discharge  and  includes  all  the  advan- 
tages claimed  for  what  u  known  as  the  peripheral  discharge  and  also 
separates  worn-out  pebbles,  and  eliminates  all  the  dust.  The  heads 
of  the  mill  are  of  the  strongest  possible  type,  being  conical  in  form. 

"Every  part  of  the  mill  is  easily  accessible,  and  all  parts  are  made 
of  the  strength  required  for  mills  to  be  used  in  American  cement  prac- 
tice. 

"The  capacity  of  the  above  mills,  when  working  in  battery,  varies 
widely  with  the  character  of  the  material,  varying  as  much  as  from  15 
barrels  per  hour  on  a  hard  Portland-cement  clinker  to  60  barrels  on 
a  natural-cement  clinker,  the  fineness  of  the  product  being  95  to  96  per 
cent  through  100-mesh,  75  to  80  per  cent  through  200-mesh. 


FIG.  104. — Exterior  view  of  Bonnot  tube  mill.     (Bonnot  &  Co.) 

"The  capacity  on  raw  rock  varies  from  8  to  10  tons  per  hour,  same 
fineness  as  mentioned  for  clinker. 

"The  capacity  of  the  tube  mill  on  coal  varies  from  3  to  4J  tons  per 
hour,  90  to  95  per  cent  through  a  100-mesh  sieve." 

Pebbles  for  tube  mills. — For  use  in  tube  mills  flint  pebbles  are  the 
most  satisfactory  grinding  materials.  These  are  obtained  chiefly  from 
Greenland,  Norway,  Denmark,  France,  and  England.  Very  little  is 
in  print  concerning  the  flint  industry,  two  recent  papers  of  interest 
being  listed  below.* 

*  Hill,  R.  T.      Flint,   an  ancient  industry.     Eng.  and  Mining  Journal,  Nov.  7, 


464  CEMENTS,  LIMES,  AND   PLASTERS. 

Concerning  the  French  flints,  Mr.  Thackara  writes  as  follows: 

"By  the  action  of  the  sea  on  the  base  of  the  chalk  cliffs,  which  form 
the  coast-line  of  a  portion  of  the  Department  of  Seine  Inferieure,  frag- 
ments of  the  rock  are  detached.  Those  which  are  composed  of  the 
flint  found  in  the  cliffs,  on  account  of  their  hardness,  are  not  reduced 
to  sand  by  the  trituration  .arising  from  the  movement  of  the  waves 
or  tidal  currents,  and  become  what '^are  known  as  sea  flint  pebbles. 
These  are  gathered  on  the  beaches  between  Havre  and  St.  Valery-sur- 
Somme,  a  distance  of  a  little  over  100  miles.  Those  which  are  nearly 
spherical  in  shape  are  carefully  selected  and  are  used  in  the  Alsing  sys- 
tem of  cylinder  grinding,  which  is  becoming  so  generally  employed 
for  pulverizing  cement,  chemical  and  pharmaceutical  products,  etc. 
The  others  are  bought  by  the  potteries  for  making  ordinary  porcelain 
ware  after  being  calcined,  ground  into  a  fine  powder,  and  mixed  with 
china  clay. 

"According  to  the  official  custom-house  statistics,  there  were  13,592 
tons  of  flint  pebbles  exported  from  France  during  1900,  valued  at 
$39,348.  The  value  of  the  declared  exports  of  these  stones  from  France 
to  the  United  States  for  the  fiscal  year  ended  June  30,  1900,  was  $16,743, 
of  which  $3849  were  shipped  from  Havre,  $4458  from  Boulogne,  and 
$8436  from  Dieppe. 

"The  prices  of  the  flint  pebbles  for  use  in  the  potteries  range  from 
5s.  3d.  ($1.27)  to  12s.  ($2.92)  per  ton  f.  o.  b.  in  bulk  at  Fecamp,  St.  Va- 
lery-en-Caux,  Dieppe,  T  report,  St.  Valery-sur-Somme,  and  Havre,  accord- 
ing to  quality  and  to  the  port  from  which  they  are  shipped.  For  the 
selected  pebbles  the  prices  vary  from  35s.  ($8.52)  to  42s.  ($10.21)  f.  o.  b., 
packed  in  barrels  or  bags,  packing  included. 

"The  rate  of  freight  from  Havre  or  Dieppe  to  New  York  averages 
10  francs  ($1.93)  per  ton  of  1000  kilograms  (2204.6  pounds). 

"French  flint  pebbles  are  shipped  to  England,  Scotland,  Norway, 
Sweden,  Russia,  Spain,  Japan,  and  the  United  States.  In  the  Baltic 
ports  they  have  to  compete  with  the  pebbles  exported  from  Denmark. 
Germany  is  now  using  silica  sand  from  the  river  Rhine  for  pottery 
purposes,  which  replaces  the  flint  pebbles.  The  French  pebbles  also 
have  to  compete  with  those  collected  on  the  English  coast  at  Newhaven, 
Shoreham,  and  Rye,  with  the  chalk  flints  shipped  from  London,  and 
with  the  Greenland  selected  pebbles." 

For  the  following  analyses  of  tube-mill  pebbles,  from  lots  furnished 
by  various  importers,  I  am  indebted  to  the  chemists  named  below. 

1903.     Thackara,  A.  M.     Export  of  sea  flint  pebbles  from  France.     U.  S.  Consular 
Report  No.  1231.     Jan.  6.  1902. 


CRUSHING  AND  PULVERIZING  MACHINERY.    . 


465 


TABLE  180. 
ANALYSES  OF  FLINT  PEBBLES. 


1. 

2. 

3. 

4. 

5. 

6. 

7. 

Silica  (SiO2) 

97.16 

95.20 

95  00 

93  05 

91  50 

90  20 

87  00 

Alumina  (Al2Os) 

Iron  oxide  (Fe2Oa) 

JO.  64 

3.40 

3.40 

6.97 

2.96 

10.10 

13.30 

Lime  (CaO)       

0  22 

1  35 

2  92 

n   d 

n   d 

1.  Greenland.     "  Dana"  brand.     H.  S.  Turner,  analyst. 

2.  Havre,  France,  light.       Heiberg  and  Roney,  analysts. 

3.  "      :  dark. 

4.  St.  Valerien,  France:  no.  1.  " 
5.,  "  "    >   :  no.  2.  " 

6.  Norway:  light.  "         "         "  " 

7.  "       :  dark. 

From  these  analyses  it  will  be  seen  what  large  variations  in  com- 
position occur  in  different  kinds  of  flint  pebbles.  Other  things  being 
equal,  the  pebbles  highest  in  silica  should  give  the  best  results,  while 
lime  is  a  particularly  injurious  impurity. 

The  high  cost  of  flint  pebbles  for  mills  situated  in  the  middle  and 
western  United  States  has  led  to  many  attempts  to  secure  a  domestic 
substitute  for  the  expensive  imported  pebbles.  Rounded  pebbles  of 
shape  and  character  suitable  for  this  use  occur  only  on  the  shores  of 
great  lakes  or  along  the  beds  of  mountain  streams.  A  California  mill 
secures  its  supply  from  the  American  river,  where  rounded  granite 
pebbles  occur  in  quantity.  These  pebbles,  gathered  by  Chinamen, 
cost  less  than  $5.00  per  ton  at  the  mill,  and  are  about  half  as  durable 
as  imported  flints.  For  grinding  3000  barrels  of  cement,  800  Ibs.  of 
granite  pebbles  were  used  up,  as  against  400  Ibs.  of  imported  flint  pebbles. 

Flint  occurs  in  several  formations  in  America,  but  in  no  case  do 
these  formations  outcrop  along  the  shore,  so  that  the  flint  can  be  obtained 
only  in  rough  angular  masses.  Along  the  north  shore  of  Lake  Superior 
hard  quartzite  pebbles  are  said  to  occur  in  quantity,  and  this  district 
may  furnish  a  supply  for  the  American  cement  trade  if  any  manufac- 
turer cares  to  investigate  the  matter. 

Class  8.  Impact  Pulverizers. 

The  impact  pulverizers  include  all  those  types  of  grinding-machines 
in  which  the  material  is  broken  by  a  blow,  in  free  space,  delivered  by 
a  series  of  rapidly  revolving  hammers,  bars,  cups  or  cages.  This  group 
therefore  includes  the  Williams  mill,  the  Raymond  pulverizer,  the  Stur- 
tevant  and  Stedman  disintegrators,  the  Cyclone  pulverizer,  and  many 
other  less  well-known  devices.  The  Stedman  disintegrator  is  exten- 
sively used  in  crushing  gypsum  or  plaster  and  natural-cement  clinker, 


466 


CEMENTS,  LIMES,  AND   PLASTERS. 


and  has,  therefore,  been  already  figured  and  described  on  pages  36,  37. 
Of  the  other  impact  pulverizers,  the  Williams  mill  is  the  only  one  ex- 
tensively used  in  Portland-cement  manufacture. 

Raymond  pulverizer. — Two  Raymond  pulverizers,  one  with  three 
rollers  and  one  with  four,  are  in  use  at  one  plant,  taking  a  dry  lime- 
stone-and-shale  mixture  from  dry-pahs  at  about  30-mesh  and  reduc- 
ing it  to  93  per  cent  through  a  100-mesh  sieve.  Each  of  these  mills 
requires  about  85  H.P.,  and  delivers  about  3|  tons  of  product  (=11J- 
barrels  cement).  This  seems  to  be  a  remarkably  high  figure  for  power, 
being  equivalent  to  about  7J-  H.P.  hours  per  barrel,  and  it  is  probable 
that  the  pulverizer  is  not  being  run  up  to  its  true  efficiency. 


\       \       \    \         X         X        ,          X        X 
FIG.  105. — View  of  Williams  mill,  casing  opened. 

Williams  mill. — The  Williams  mill  is  shown  in  view,  with  its  casing 
opened,  in  Fig.  105,  and  in  section  in  Fig.  1C6.  It  will  be  seen  that 
it  crushes  by  the  blows  of  a  series  of  hammers,  rapidly  revolving  about 
a  horizontal  central  axis. 

The  following  record  of  an  actual  working  test,  communicated  to 
me  by  the  chemist  of  a  plant  using  the  Williams  mill  on  its  raw  mate- 
rials, will  serve  to  show  the  percentages  on  different  sieves  that  are 


CRUSHING  AND   PULVERIZING  MACHINERY. 


467 


produced  by  this  mill.  At  the  plant  in  question  the  materials  used 
are  hard  limestone  and  shale.  The  raw  materials  are  run  through 
a  Gates  crusher,  which  gives  a  product  averaging  1J  inches  in  size. 


FIG.  106. — Section  of  Williams  mill. 


Three  Williams  mills,   using  about   18  H.P.  each,  take    the    product 
from  this  crusher  and  reduce  it  to  give  the  following  residues: 

Mesh  of  sieve 20  50  100  200 

Per  cent  residue 25        45.1         60.9         69.5 

Per  cent  passing 75         54 . 9         39 . 1         30 . 5 

The  three  Williams  mills  in  use  handle  sufficient  raw  mix  to  give 
a  production  of  about  1000  barrels  per  day.  From  these  mills  the 
material  is  fed  to  three  tube  mills,  which  take  up  60  to  70  H.P.  each,  and 
complete  the  reduction  so  that  92  to  93  per  cent  passes  a  100-mesh 
sieve. 

Another  test,  for  the  record  of  wrhich  I  am  indebted  to  the  manu- 
facturers of  the  Williams  mill,  was  carried  on  in  a  plant  also  using  lime- 
stone and  shale,  crushed  to  about  1J  inch  size. 

Mesh  of  sieve 20  50  100  200 

Per  cent  residue 26.8        51.3         68.7        76.0 

Per  cent  passing 73.2        48.7        31.3        24.0 


468  CEMENTS,  LIMES,  AND   PLASTERS. 

The  writer  has  seen  the  Williams  mill  in  operation  at  a  number 

of  Portland-cement  plants,  working  on  various  raw  materials  and  also 

on  cement  clinker.     Its  results  when  operating  on  shales,  slates  or  thin 

bedded  slaty  limestone  are  remarkably  good,  and  the  machine  appears 

to  be  particularly  well  adapted  for  such  materials. 

References    on    crushing    machinery. —  The    following   books   and 

papers  contain  matter  of  interest   in    this    connection,  Richard's  work 

being,  of  course,  by  far  the  most  important: 

Blake,  W.  P.  The  Blake  stone  and  ore-breaker;  its  ^invention,  forms  and 
modifications.  Trans.  Amer.  Inst.  Mining  Engrs.,  vol.  33,  pp.  988- 
1031.  1903. 

Fischer,  H.  The  operator  of  a  tube  mill.  Engineering  and  Mining  Journal, 
Nov.  17,  1904,  pp.  791-793. 

Fraser,  G.  H.  Recent  results  obtained  with  the  Kent  mill  as  a  fine  grinder. 
Cement,  vol.  6,  pp.  74-79.  May,  1905. 

Hutchinson,  W.  S.  The  plotting  of  sizing  tests.  Transactions  Amer.  Inst. 
Mining  Engineers,  1904. 

Lesley,  R.  W.  The  manufacture  of  cement.  Trans.  Am.  Soc.  C.  E.,  vol. 
LIV,  part  B,  pp.  89-130.  1905. 

Richards,  R.  H.     Ore  Dressing.     2  vols,  8vo,  pp.  1236.     1903. 

Schvverin,  M.  Notes  on  some  regrinding  machines.  Engineering  and  Min- 
ing Journal,  Mch.  10,  1904,  pp.  403-404. 

Anon.  The  pebble  tube  mill  in  metallurgy.  Electrochemical  and  Metal- 
lurgical Industry,  vol.  3,  pp.  41-42.  Jan.,  1905. 


CHAPTER  XXXII. 
CEMENT  BURNING:    FIXED  KILNS 

THE  preceding  chapters  have  been  devoted  to  a  discussion  of  the 
raw  materials  for  Portland-cement  manufacture,  and  to  the  processes 
and  methods  of  preparing  a  mixture  of  these  materials  for  the  kiln.  In 
the  present  and  following  chapters  the  next  stage  of  the  industry  will 
be  taken  up — that  of  burning  the  raw  mix  into  cement  clinker. 

Fixed  or  Stationary  Kilns. 

The  earliest  type  of  kiln  used  in  Portland-cement  manufacture  was  a 
simple  vertical  bottle-shaped  kiln  closely  similar  to  those  used  in  the 
burning  of  lime  and  natural  cements.  This  was  largely  succeeded  by 
improved  types  of  stationary  kilns  in  Germany  and  France,  while 
in  the  United  States  the  rotary  kiln  has  become  standard.  Though 
stationary  kilns  are  now  very  rare  in  American  practice  they  have  some 
undoubted  advantages  in  localities  where  fuel  is  expensive  and  labor 
is  cheap.  As  American  engineers  may  soon  have  to  consider  the  pos- 
sibility of  manufacturing  cement  in  Central  and  South  America,  where 
these  fuel  and  labor  conditions  are  fulfilled,  it  has  been  considered 
advisable  to  discuss  the  improved  type  of  stationary  kilns  in  some 
detail.  A  list  of  references  to  the  more  important  papers  on  the  sub- 
ject is  also  given  at  the  end  of  the  chapter. 

In  order  that  the  relationships  of  the  various  types  of  fixed  or  sta- 
tionary kilns  may  be  clearly  understood,  it  will  be  well  to  group  them 
in  classes  according  to  the  general  principles  on  which  their  construc- 
tion and  operation  are  based.  Four  such  groups  can  be  formed: 

1.  Dome  or  intermittent  kilns. 

2.  Dome  kilns  with  drying  accessories. 

3.  Ring  or  Hoffmann  kilns. 

4.  Continuous  shaft  kilns. 

These  classes  will  be  described  in  the  order  named. 

469 


470 


CEMENTS,  LIMES,  AND  PLASTERS. 


I.  Dome  or  Ordinary  Intermittent  Kilns. 

All  intermittent  kilns  will,  for  convenience,  be  here  termed  dome 
kilns,  though  the  term  is  properly  restricted  to  intermittent  kilns  of 
one  particular  shape. 


FIG.  107.— Dome  kiln 

The  dome  or  bottle-shaped  kiln  is  the  original  form  on  which  most 
fixed  kilns  are  based.  As  shown  in  Fig.  1C7  it  is  practically  the  shape 
of  the  older  lime-kilns,  differing  usually  in  having  a  somewhat  greater 
height  for  a  given  diameter.  The  type  shown  in  the  figure,  which  is 
the  ordinary  English  form,  is  perhaps  9  to  12  feet  in  diameter  at  its 
widest  portion,  15  to  18  feet  from  its  base  to  this  widest  zone,  and 
25  to  35  feet  in  total  height.  This  kiln  is  usually  charged  at  several 
levels,  one  charging  door  being  located  a  little  below  its  widest  point, 
and  others  being  opened  in  the  truncated  cone  which  serves  as  a  chimney. 

In  German  practice  these  kilns  assumed  a  form  nearly  like  that 
of  the  blast-furnace.  The  bo-dy  of  the  German  dome  kiln  is  usually 


CEMENT  BURNING:  FIXED  KILNS.  471 

a  cylinder,  9  to  12  feet  wide  and  25  to  30  feet  high.  This  is  surmounted 
by  a  truncated-cone  chimney,  often  high  so  that  the  total  height  of 
the  kiln  may  be  35  to  75  feet.  Candlot  states  that  at  some  German 
plants  kilns  22  feet  in  diameter  and  100  feet  in  height  were  used,  each 
of  which  kilns  would  turn  out  400  tons  (metric)  of  cement  for  each  run. 
Dome  kilns  are  charged  with  fuel  and  mix,  the  latter  in  the  form  of 
bricks,  in  alternate  layers,  the  proportions  varying  principally  with 
the  height  of  the  kiln  and  the  wetness  of  the  bricks  of  mix.  When 
the  kiln  is  full  the  charging  doors  are  closed  and  luted  with  fire-clay, 
and  the  lowest  layer  of  fuel  is  ignited.  As  the  burning  progresses  the 
entire  mass  settles,  owing  to  the  loss  in  fuel  and  carbon  dioxide.  The 
kiln  may  now  be  refilled  to  its  former  level,  but  nothing  is  drawn  from 
it  until  the  burning  is  complete,  which  may  take  from  one  to  two  weeks. 
Candlot  states  that  the  production  of  a  dome  kiln  varies  from  J  to  1  ton 
of  clinker  for  each  cubic  meter  of  burning  space,  and  that  from  23  to 
30  Ibs.  of  fuel  are  required  per  100  Ibs.  of  clinker,  the  latter  quantity 
varying  according  to  whether  anthracite,  gas-coke,  or  oven-coke  is 
employed.  The  labor  cost  of  charging,  drawing,  and  picking  clinker 
from  the  dome  kiln  may  vary  from  30  to  50  cents  per  ton  of  cement, 
equivalent  to  about  5  to  10  cents  per  barrel. 

2.  Dome  Kilns  With  Drying  Accessories. 

The  first  and  simplest  improvement  on  the  primitive  dome  kiln 
was  to  provide  each  kiln  with  a  drying  tunnel.  The  kiln  thus  improved 
was  still  intermittent,  but  the  drying  tunnel  gave  a  certain  fuel  economy, 
particularly  when  very  wet  mixes  were  employed.  The  principal  type 
of  this  class  of  kiln  is  the  Johnson  kiln. 

Johnson  kiln. — The  Johnson  or  chamber  kiln  was  apparently  the 
first  English  improvement  on  the  simple  dome  kiln.  It  consists  essen- 
tially of  a  dome  kiln  roofed  over  at  the  top,  and  with  a  long  horizontal 
passage,  semi-circular  in  section,  opening  into  the  kiln  near  the  top 
and  leading  to  a  stack.  The  wet  slurry  is  placed  in  the  horizontal 
passage  and  dried  by  the  hot  gases  passing  through  it  irom  the  kiln 
to  the  stack.  The  slurry  when  dry  must  be  shovelled  up  and  charged 
into  the  kiln  by  hand. 

Various  modifications  of  the  Johnson  kiln  have  been  suggested 
and  used  in  English  plants,*  most  of  them  depending  for  extra  economy 
on  passing  the  hot  gases  under  as  well  as  over  the  slurry  to  be  dried. 

The  Johnson  kiln,  with  its  different  modifications,  may  be  considered 


Proc.  Institution  Civil  Engineers,  vol.  62,  pp.  74-76.     1880. 


472 


CEMENTS,  LIMES,  AND   PLASTERS. 


•essentially  as  combinations  of  old-style  dome  kilns  and  drying-floors. 
They  utilize  waste  heat  for  drying  the  slurry;  and  are,  therefore,  more 
-economical  in  fuel  consumption  than  is  the  single-dome  kiln.  They 
are  all  based  on  intermittent  working  of  the  kiln,  however;  and  in  all, 
the  dried  slurry  must  be  charged  into  the  kiln  by  hand. 

Six  Johnson  kilns  were  installed  irf  1890  at  the  plant  of  the  Western 


Ctiimuey 


SECTION 


Gate 


Chimney 


Drying_space.  for  .Slurry 

1  ,    , 

jR 

Kiln 


FIG.  108. — Plan  and  section  of  Johnson  kiln.     (Engineering  News.) 

Portland  Cement  Company,  Yankton,  S.  D.,  but  have  recently  been 
Teplaced  by  rotaries.  I  believe  that  similar  kilns  were  used  in  the  first 
plant  at  Whitecliffs,  Ark. 

3.  Ring  or  Hoffmann  Kilns. 

The  Hoffmann  or  ring  kiln  has  been  used  quite  extensively  in  Ger- 
many for  burning  Portland  cement,  lime,  and  bricks,  but  has  never 
•come  into  favor  in  either  England  or  the  United  States.  It  consists 
•essentially  of  a  number  of  chambers  arranged  in  a  circle  or  ellipse  around 
a  central  stack.  Three  flues  lead  from  each  chamber  to  (1)  the  cen- 
tral stack,  (2)  the  chamber  preceding  it  in  the  series,  and  (3)  the  chamber 
following  it  in  the  series.  Each  of  these  flues  may  be  closed  at  will 
by  the  insertion  of  a  partition  of  sheet  iron.  Each  chamber  also  has 
a  door  opening  to  the  outside  of  the  kiln  and  used  for  charging  and 
•drawing. 

Assuming  that  the  kiln  is  entirely  empty  (a  condition  which  could 
occur  only  in  firing  up  a  newly  built  kiln),  the  operations  would  be  as 
iollows:  Each  chamber  would  be  loaded  with  bricks  of  dried  slurry 
.stacked  up  as  in  a  brick  kiln.  Slack  or  other  fine  coal  is  fed  in  at  the 

I 


CEMENT   BURNING:  FIXED  KILNS. 


473 


top  of  the  chambers  and  one  chamber  is  fired.  All  of  the  flues  in  the 
kiln  leading  to  the  stack  are  closed  except  one,  i.e.,  the  flue  from  the 
chamber  behind  the  one  which  has  been  fired.  All  the  inter-chamber 
flues  are  open  except  one,  i.e.,  the  flue  between  the  fired  chamber  and 


FIG.  109.— Section  of  Hoffmann  kiln. 

the  one  immediately  behind  it  in  the  series.  The  result  of  this  arrange- 
ment is  that  the  hot  gases  from  the  fired  chamber  pass  in  turn  through 
each  of  the  other  loaded  chambers  until  they  arrive  in  the  chamber 
immediately  behind  the  fire,  when  they  are  passed  into  the  central 
stack.  The  waste  heat  from  the  fired  chamber  is  therefore  utilized 
to  the  fullest  extent  in  heating  up  all  the  other  chambers. 

When  the  slurry  in  the  fired  chamber  is  converted  into  clinker  this 
is  allowed  to  cool.  The  chamber  is  then  temporarily  cut  off  from  the 
rest  of  the  series  by  closing  its  flues  and  the  clinker  is  drawn.  In 
the  meantime  the  chamber  next  to  it  has  been  fired.  The  empty  cham- 


474  CEMENTS,  LIMES,  AND  PLASTERS. 

her  is  recharged  and  the  flues  to  the  central  stack  and  from  the  chamber 
behind  it  are  opened,  thus  making  the  newly  filled  chamber  the  end 
term  of  the  series. 


FIG.  110.— Plan  of  Hoffmann  kiln.' 

As  noted,  the  slurry  charged  into  a  Hoffmann  kiln  is  necessarily  in 
the  form  of  bricks.  The  expense  of  partly  drying  the  slurry  and  mold- 
ing it  into  bricks  must,  therefore,  be  charged  against  the  kiln.  Taken 
as  a  whole  the  system  is  low  in  fuel  consumption,  but  high  in  labor 
cost,  especially  since  skilled  labor  is  required  for  all  the  operations. 
Usually  one  chamber  is  loaded  and  one  drawn  each  day.  The  out- 
put per  kiln  per  day  will,  therefore,  depend  on  the  size  of  the  chambers. 

4.  Continuous  Shaft  Kilns. 

Die tzsch  kiln. — In  1884  the  Dietzsch  kiln  was  first  used  in  cement- 
manufacture,  and  its  advantages  soon  became  known.  It  has  been 
in  use  at  several  American  plants,  and  in  the  matter  of  fuel  consumption 
is,  perhaps,  the  best  type  of  kiln  that  can  be  employed. 

Dietzsch  kilns  are  built  in  pairs,  back  to  back,  as  shown  in  Fig.  111. 
They  are  60  to  75  feet  h  gh,  and  consist  of  a  cooling  chamber  at  the 
base  D,  a  fire-chamber  or  "creuset"  C,  and  a  preheating  chamber  A. 
It  will  be  seen  that  these  three  parts  of  the  kiln  are  not  all  in  one  ver- 
tical alignment,  but  that  the  axis  of  the  preheating  chamber,  though 
parallel  to  the  axis  of  the  main  kiln,  is  off  to  one  side  some  distance, 
so  that  the  two  portions  of  the  structure  communicate  by  a  horizontal 
passage  B. 

Aalborg  or  Schofer  kiln. — The  Aalborg  kiln,  soon  introduced  in 
European  cement  practice  after  the  success  of  the  Dietzsch  kiln  had 
proven  the  possibility  of  economical  continuous  kilns,  has  been  used 
at  several  American  plants  in  a  more  or  less  modified  form.  The  kiln 
is  shown  in  section  in  Fig.  112.  It  will  be  seen  that  it  is  essentially  the 
same  as  the  Dietzsch,  except  that  the  preheating  chamber,  the  burning 
space,  and  the  cooling  chamber  are  all  in  the  same  vertical  line.  This 
change,  slight  in  appearance,  economizes  considerably  in  labor,  for  the 
charge  descends  of  itself,  without  the  rehandling  necessary  in  the  Dietzsch 
kiln.  The  mix  is  introduced  through  the  charging  opening  A,  while 
the  coal  is  charged  through  the  shutes  (shown  in  the  figure  about  an 
inch  below  A). 


CEMENT   BURNING:  FIXED  KILNS. 


475 


In  European  practice  Candlot  states  that  an  Aalborg  kiln  will  turn 
out  10  to  15  tons  of  clinker  per  day,  with  a  fuel  consumption  of  280  Ibs. 
coal  per  ton  of  product. 


FIG.  111.— Dietzsch  kilns. 


Hauenschild  kiln. — The  Hauenschild  kiln  is  a  simple  cylinder,  charged 
at  the  top  with  both  fuel  and  mix.  It  differs  from  a  cylindrical  lime- 
kiln only  in  having  two  distinct  walls,  with  a  space  between.  This  annu- 
lar space  is  used  either  for  drying  the  mix  or  for  heating  the  air  to  be 
supplied  to  the  kiln.  The  result  is  that  the  interior  lining  is  kept  fairly 
cool,  so  that  the  charge  does  not  clinker  in  masses  against  the  walls, 


476 


CEMENTS,  LIMES,  AND   PLASTERS, 


FIG.  112.— Section  of  Schofer  kiln. 


CEMENT   BURNING:  FIXED   KILNS. 


477 


which  is  the  principal  defect  encountered  in  running  a  vertical  kiln* 
continuously. 


FIG.  113. — Hauenschild  kiln. 

Schwarz  kiln. — In  a  recent  paper  on  the  manufacture  of  Portland 
cement  from  a  mixture  of  slag  and  limestone  C.  von  Schwarz  describes 
a  kiln  used  at  a  German  cement  plant.  This 
kiln,  here  called  the  Schwarz  kiln,  is  shown  in 
partial  section  in  Fig.  114.  It  is  described  as 
follows : 

Each  kiln  consists,  in  its  essential  part  of  a 
series  of  rings,  each  1  inch  to  1J  inches  in  thick- 
ness, 8J  feet  inner  diameter,  and  18  inches  in 
height.  These  rings  are  provided  outside  with 
ribs,  r,  Fig.  112,  and  placed  in  such  a  way,  one 
above  the  other,  that  the  vertical  ribs  cover  one 
another,  thus  forming  little  vertical  channels 
c,  c,  c  all  around,  in  which  the  air  circulates 
from  below  to  the  top,  like  in  a  chimney,  thus 
continually  cooling  the  cast-iron  rings  from  the  s.  SECTION  a-b 

outside,  and  preventing  them  from  getting  over-  FIG.  114.— Partial   plan 
•       i    j       .m  •   ?  i      i  i-  and  section  of  Schwarz, 

heated.     The  materials  to  be  burnt  are  in  direct     kiln.       (Engineering 

contact  with  the  cast-iron  rings,  no  lining  of  any     News). 

kind  being  provided  for.    'There  are  18  such  rings,  put  one  above  the 


478  CEMENTS,  LIMES,  AND  PLASTERS. 

other,  the  upper  rings — where  the  greatest  heat  occurs — being  hooped 
at  the  joints.  The  top  of  each  kiln  is  provided  with  a  cone  and  a  chimney 
made  of  sheet  iron,  3  feet  in  diameter  and  30  feet  in  height.  The  cone 
has  four  charging  doors,  which  can  be  closed  by  sheet-iron  covers  as 
soon  as  the  charging  is  done. 

At  a  depth  of  12  feet  from  the  top  the  inner  diameter  of  the  kiln 
is  lessened  to  nearly  half  its  inner  horizontal  section,  and  on  this  zone 
is  provided  with  a  double  row  of  tuyeres  to  admit  compressed  air,  this 
arrangement  having  for  its  object  to  burn  any  carbpjiic  oxide  or  carbu- 
retted  hydrogen  gas  arising  from  below  as  completely  as  possible,  as 
well  as  to  concentrate  the  heat  exactly  where  it  is  required,  viz.,  on 
the  place  where  the  formation  of  the  clinker  is  to  take  place. 

Compressed  air  is  also  introduced  from  below  in  two  places.  The 
pressed  air  is  produced  by  a  ventilator,  the  pressure  being  }  inch  to  1} 
inches  of  water.  One  charge  consists  of  100  bricks  and  65  to  70  Ibs. 
of  coke  as  fuel;  one  third  of  the  coke  could  be  rep'aced,  if  necessary, 
by  anthracite  or  other  small  coal. 

As  a  rule,  four  kilns  are  arranged  in  one  set,  being  provided  with  a 
common  elevator  and  a  common  platform,  for  all  four  kilns  together. 
They  are  surrounded  by  a  scaffolding  made  of  angles  and  tees,  on  which 
the  staircase  to  mount  the  platform  is  fixed.  At  the  same  time  cor- 
rugated galvanized  sheets  are  riveted  on  this  scaffolding  all  round,  in 
order  to  prevent  unequal  cooling  of  the  furnaces  outside  in  case  of  rain, 
wind,  or  snow. 

The  principal  advantage  of  a  kiln  of  this  description  is  that,  owing 
to  the  continuous  and  regular  cooling  from  outside,  the  fritted  clinker 
cannot  clog  the  interior  of  the  furnace,  thus  ensuring  a  regular  and 
continuous  working  of  the  furnace.  The  ribs  at  the  same  time  give 
strength,  and  prevent  the  cast-iron  rings  from  warping.  Each  fur- 
nace produces  about  25  tons  of  well-burnt  clinker,  equal  to  as  much 
finished  cement,  in  twenty-four  hours. 

Reference  list  for  fixed  kilns. — The  design,  construction,  and  opera- 
tion of  vertical  or  stationary  kilns  of  various  types  are  discussed  in 
many  books  and  papers  on  Port  land -cement  manufacture.  The  most 
satisfactory  of  these  discussions  are  included  in  the  following  annotated 
list  of  references  on  the  subject: 

Butler,  D.  B.  Portland  Cement:  its  manufacture,  testing,  and  use.  1899. 
Chapter  IV  of  this  volume,  pp.  71-102,  includes  descriptions  of  the 
dome  kiln,  Johnson  kiln,  Batchelor  kiln,  Dietzsch  kiln,  and  Hoffmann 
kiln.  The  discussion  of  the  Johnson  kiln  and  its  modifications  is  par- 
ticularly valuable. 


CEMENT   BURNING:  FIXED  KILNS.  479 

Candlot,  E.  Ciments  et  chaux  hydrauliques.  1898.  Fixed  kilas  of  various 
types  are  well  described  on  pp.  53-71,  inclusive. 

Lewis,  F.  H.  The  Candlot  oscillating  grate  for  cement  kilns.  Engineering 
Record,  May  21,  1898.  Description  of  a  grate  devised  to  improve  draft 
and  prevent  balling  in  shaft  kilns. 

Schoch,  C.  Die  moderne  Aufbereitung  und  Wertung  der  Mortel-Materialen. 
1896.  Pages  124-157  of  this  volume  contain  descriptions  of  various 
improved  types  of  fixed  kilns.  Those  of  the  Hoft'ma;nn>  Dietzsch,  Stein, 
Hanenschild,  and  Schofer  kilns  are  particularly  valuable. 

Scott,  H.  S.  D.,  and  Redgrave,  G.  R.  The  manufacture  and  testing  of  Portland 
cement.  Proc.  Inst.  Civ.  Engrs.,  vol.  62,  pp.  67-86.  1880. 

The  Johnson  kiln  and  i.ts  modifications  are  described  in  considerable 
detail  on  pp.  74-76. 

Stanger,  W.  H.,  and  Blount,  B.  The  rotatory  process  of  cement-manufacture. 
Proc.  Inst.  Civ.  Engrs.,  vol.  165,  pp.  44-136.  1901.  Valuable  data 
on  the  design,  construction,  and  results  obtained  from  various  types 
of  fixed  kilns  will  be  found  on  pp.  44,  48,  81,  82,  99,  and  100. 

Von  Schwarz,  C.  The  utilization  of  blast-furnace  slag.  Journal  Iron  and  Steel 
Institute,  1900,  No.  1,  pp0  141-152.  1900.  The  Schwarz  kiln  is  de- 
scribed with  figures. 

Zwick,  H.  Hydraulischer  Kalk  und  Portland-Cement.  1892.  Pages  148- 
184  are  devoted  to  discussions  of  kilns  and  burning  practice.  The 
Hoffmann  ring  kiln  is  described  in  great  detail. 


CHAPTER  XXXIII. 
THE     ROTARY     KILN. 

IN  the  early  days  of  the  Portland-cement  industry  a  simple  vertical 
kiln,  much  like  that  used  for  burning  lime  and  natural  cement,  was 
used  for  burning  the  Portland-cement  mixture.  These  kilns,  while 
fairly  efficient  so  far  as  fuel  consumption  was  concerned,  were  expen- 
sive in  labor,  and  their  daily  output  was  small.  In  France  and  Ger- 
many they  were  soon  supplanted  by  improved  types,  but  still  stationary 
and  vertical,  which  gave  very  much  lower  fuel  consumption.  Kilns 
of  these  types  have  been  discussed  in  the  preceding  chapter.  In  America, 
however,  where  labor  is  expensive  while  fuel  is  comparatively  cheap, 
an  entirely  different  style  of  kiln  has  been  evolved.  This  is  the  rotary 
kiln.  With  the  exception  of  a  very  few  of  the  older  plants,  which  have 
retained  vertical  kilns,  all  American  Portland-cement  plants  are  now 
equipped  with  rotary  kilns. 


FIG.  115. — Exterior  view  of  rotary  kiln.      (Bonnot  &  Co.) 

The  rotary  kiln  as  at  first  used  in  cement-manufacture  was  adapted 
to  dry  materials  only,  while  gas  or  oil  were  used  as  fuel.  A  long  series 
of  experiments  and  improvements  have  perfected  a  burning  process 
in  which  finely  pulverized  coal  is  used  as  fuel,  while  wet  mixtures  can 
now  be  fed  directly  to  the  kiln.  The  present  condition,  in  which  the 
rotary  kiln  is  adapted  to  the  use  of  several  different  types  of  fuel,  and 
to  all  kinds  of  Portland-cement  mixtures,  has  been  attained  only  through 
long  and  earnest  effort  on  the  part  of  American  cement-manufacturers. 

480 


THE   ROTARY   KILN. 


481 


The  history  of  the  gradual  evolution  of  the  rotary  is  of  great  interest, 
but  as  the  subject  cannot  well  be  taken  up  here,  reference  should  be 
made  to  the  papers  cited  below,*  which  contain  the  details  of  this  his- 
tory, accompanied  in  many  cases  by  illustrations  of  early  forms  of  rotary 
kilns. 

Summary  of  burning  process. — As  at  present  used,  the  rotary  kiln 
Is  a  steel  cylinder,  about  5  to  7  feet  in  diameter;  its  length  for  dry 
materials  is  60  to  150  feet,  while  for  wet  mixtures  an  80-foot  or  even 
longer  kiln  is  commonly  employed. 

This  cylinder  is  set  in  a  slightly  inclined  position,  the  inclination 


^»^    ~~*j 


FIG.  116. — Plan  and  elevation  of  60-foot  rotary  kiln.     (Engineering  News) 

being  approximately  one  half  inch  to  the  foot.  The  kiln  is  lined,  ex- 
cept near  the  upper  end,  with  very  resistant  fire-brick,  to  withstand 
both  the  high  temperature  to  which  its  inner  surface  is  subjected  and 
also  the  destructive  action  of  the  molten  clinker. 

*  Duryee,  E.     The  first  manufacture  of  Portland  cement  by  the  direct  rotary  kiln 

process.     Engineering  News,  July  26,  1900. 
Eckel,  E.  C.     Early  history  of  the  Portland-cement  industry  in  New  York  State. 

Bulletin  44,  New  York  State  Museum,  pp.  849-859.     1901. 
Lesley,   R.   V/.     History  of  the  Portland-cement  industry  in  the  United  States. 

8vo,  146  pp.     Philadelphia,  1900. 
Lewis,  F.  *H.     The  American  rotary  kiln  process  for  Portland  cement.     Cement 

Industry,  pp.  188-199.     New  York,  1900. 
Matthey,   H.     The   invention   of  the  new   cement-burning   method.     Engineering 

and  Mining  Journal,  vol.  67,  p.  555,  705.     1899. 
Smith,  W.  A.     Manufacture  of  cement,  1892.     Mineral  Industry,  vol.  1,  pp.  49-53. 

1893. 
Stanger,   \V.    H.,  and  Blount,   B.     The  rotatory  process  of  cement-manufacture. 

Proc.  Institution  Civil  Engineers,  vol.  145,  pp.  44-136.      1901. 
Editorial.     The  influence  of  the  rotary  kiln  on  the  development  of  Portland-cement 

manufacture  in  America.     Engineering  News,  May  3,  1900 


482 


CEMENTS,  LIMES,  AND  PLASTERS. 


The  cement  mixture  is  fed  in  at  the  upper  end  of  the  kiln,  while  fuel 
(which  may  be  either  powdered  coal,  oil,  or  gas)  is  injected  at  its  lower 
end.  The  kiln,  which  rests  upon  geared  bearings,  is  slowly  revolved 
about  its  axis.  This  revolution,  in  connection  with  the  inclination 
at  which  the  cylinder  is  set,  gradually  carries  the  cement  mixture  to 
the  lower  end  of  the  kiln."'  In  the  Bourse  of  this  journey  the  intense 
heat  generated  by  the  burning  fuel  first  drives  off  the  water  and  car- 
bon dioxide  from  the  mixture  and  then  causes  the  lime,  silica,  alumina, 
and  iron  to  combine  chemically  to  form  the  partialjy  fused  mass  known 
as  "cement  clinker".  This  clinker  drops  out  of  the  lower  end  of  the 
kiln,  is  cooled  so  as  to  prevent  injury  to  the  grinding  machinery,  and 
is  then  sent  to  the  grinding  mills. 

Shape  and  size. — The  rotary  kilns  in  use  at  various  plants  differ 
considerably  in  both  shape  and  size. 


FIG.  117. — Driving  mechanism  of  rotary  kiln.     (Engineering  News.) 

As  to  shape,  the  simplest  and  commonest  form  is  that  of  a  cylin- 
der— a  straight  tube  of  equal  diameter  throughout.  At  many  plants, 
however,  the  kilns  are  wider  at  the  lower  or  discharge  end  than  at  the 
stack  end.  This  is  usually  accomplished  by  means  of  a  reducing  sec- 
tion near  the  middle  of  the  kiln,  so  that  a  kiln  of  thi3  type  would  con- 
sist really  of  a  lower  section  6  feet  in  diameter  and  about  30  feet  long, 
.an  upper  section  5  feet  in  diameter  and  30  feet  long,  and  an  intermediate 
reducing  section  in  the  shape  of  a  frustum  of  a  cone.  The  theory  on 
which  this  arrangement  is  nominally  based  is  that  the  gases,  cooling 
<as  they  near  the  upper  end,  should  be  confined  in  smaller  space  to  keep 
up  their  efficiency.  I  am  informed  by  Mr.  Seaman,  however,  that  the 
jfirst  kilns  built  in  this  way  were  made  at  the  Atlas  plant,  during  the 
early  experiments,  merely  as  a  makeshift  to  utilize  two  30-foot  kilns 
of  different  diameters  which  happened  to  be  on  hand. 


THE   ROTARY  KILN. 


4S3 


The  variations  in  size  are  greater  and  more  important  than  those 
in  shape.  Until  within  two  years  ago  it  could  be  said  that  the  standard 
dry-process  kiln  was. 60  feet  in  length  and  about  6  feet  in  diameter,  while 


PLAN  OF  BASE 


GUIDE  ROLLERS  AND  STANDARD 

ROLLER  BEARING  AND  DRIVING  RACK  AT  HEAD  END. 


PLAN 


STANDARD  DETAILS 
ROLLER  BEARING  OF  TAIL  END. 


END  ELEVATION  SIDE  ELEVATION 

HOOD  OF  DISCHARGE  END. 


FIG.  118. — Details  of  60-foot  rotary  kiln.      (Engineering  News.) 

in  the  wet  process  the  length  ranged  from  60  to  80  feet.  These  lengths 
had  become  well  established  in  practice,  soon  after  the  rotary  kiln  list 
proved  successful,  and  for  many  years  it  seemed  as  if  practice  had  become 
fixed  in  this  line  at  least. 


484 


CEMENTS,  LIMES,  AND  PLASTERS. 


Several  years  ago  Mr.  Edison  installed  a  150-foot  kiln  in  4iis  New 
Jersey  plant.  The  success  attained  by  this  kiln  was  masked  for  a  time 
by  defects  in  other  portions  of  the  plant's  equipment,  but  as  soon  as  it 
became  apparent  every  manager  in  the  United  States  began  to  con- 
sider the  possibility  of  lengthening  his  kilns.  The  Edison  kiln  was  re- 


IP 


FIG.   119. — Raw  material  storage-bin,  with  adjustable  feeder  driven  from  kiln 
countershaft.     (Allis-Chalmers  Co.) 

ported  to  yield  350  to  375  barrels  of  cement,  per  day,  with  a  fuel  con- 
sumption of  only  65  Ibs.  of  coal  per  barrel.  Sixty-foot  kilns,  on  the 
other  hand,  usually  gave  160  to  180  barrels  a  day  when  working  on  a 
dry  limestone-clay  mix,  and  might  use  110  to  150  pounds  of  coal  per 
barrel.  In  the  Lehigh  district,  working  on  the  easily  clinkered  cement 
rock,  results  were  better,  but  even  here  the  maximum  production  could 
hardly  exceed  225  bbls.  per  day,  with  a  fuel  consumption  perhaps  as 
low  as  95  to  120  pounds.  « 

Such  a  contrast  was  too  striking  to  permit  much  delay  in  lengthen- 


THE  ROTARY  KILN. 


485 


486  CEMENTS,  LIMES,  AND   PLASTERS. 

ing  kilns,  and  at  present  kilns  of  80  feet  in  length  are  common,  while 
several  of  the  best  plants  have  installed  kilns  respectively  100,  107,  and 
110  feet  long. 

In  the  writer's  opinion,  however,  the  most  remarkable  development 
of  recent  years  has  been  in  an  entirely  different  direction.  Several 
plants  in  the  United  States  "are  at  present  forcing  their  60-foot  kilns  in 
such  a  way  as  to  give  over  300  barrels  per  day  of  good  cement.  This 
remarkable  performance  is  not  accompanied,  it  is  true,  by  any  saving  in 
the  amount  of  coal  used  per  barrel ;  but  even  so,  the  production  is  worthy 
of  note.  The  above  statements  as  to  production  may  be  taken  as  ac- 
curate. 

Feeding  coal  to  the  kiln. — In  Fig 3.  121  and  122  is  shown  a  typical 
coal-feeding  installation,  being  one  supplied  by  the  B.  F.  Sturtevant  Co. 
for  the  plant  of  the  International  Portland  Cement  Co.,  at  Durham, 
Ontario.  For  the  following  description  of  this  installation  I  am  indebted 
to  the  manufacturers. 

The  coal  is  crushed,  dried,  and  pulverized  in  the  coal-house,  located 
independently  of  kiln-room.  It  is  very  essential  to  the  proper  burn- 
ing of  the  coal  that  it  be  well  dried  and  pulverized.  At  least  88  per 
cent  of  the  coal  should  pass  a  100-mesh  screen.  The  finer  the  coal  is 
pulverized,  the  more  advantageously  can  it  be  burned. 

Pulverized  coal  is  transferred  from  coal-house  to  storage-bins  A, 
located  directly  in  front  of  kilns,  by  means  of  an  overhead-screw  con- 
veyor B,  which  discharges  the  pulverized  coal  into  top  of  storage- 
bins.  Each  kiln  has  an  independent  storage-hopper  which  holds  from 
ten  to  eighteen  hours  supply  of  pulverized  coal. 

Pulverized  coal  is  fed  from  the  storage-hoppers  into  the  injectors 
//  by  means  of  a  small  screw  conveyor  C,  located  at  bottom  of  storage- 
bin,  amount  of  coal  handled  by  each  injector  being  dependent  upon  the 
speed  of  the  corresponding  screw  conveyor.  The  screw  conveyor  C 
is  driven  by  a  variable-speed  machine  D  through  a  series  of  gears,  so 
that  the  speed  of  the  conveyor  can  be  regulated  according  to  operating 
conditions  of  plant,  which  vary  to  a  great  extent  in  most  plants.  The 
variable-speed  machine  is  driven  from  a  light-line  shaft  E,  usually  located 
on  front  of  coal-hoppers „  Pulley  F  on  variable-speed  machine  is  pro- 
vided with  a  friction-clutch  so  that  any  unit  consisting  of  kiln,  storage- 
hopper,  etc.,  can  be  shut  down  for  repairs  without  interfering  with  the 
remainder  of  the  plant. 

For  furnishing  blast,  two  special  gas-exhausters  G  are  provided> 
each  exhauster  being  of  sufficient  capacity  to  operate  all  injectors, 
the  other  exhauster  being  held  in  reserve  in  case  of  accident  to  the  first. 


THE  ROTARY  KILN. 


487 


The  blast-fans  are  so  arranged  that  the  reserve  fan  could  be  placed 
in  service  in  case  of  accident  to  the  operating  fan  before  kilns  have 
time  to  cool  to  any  great  extent;  after  the  kiln  has  cooled  or  when 
starting  the  kiln  for  burning  clinker;  it  requires  several  hours  to  heat 


DETAIL  ELEVATION  OF  FEEDING  MECHANISM 


DETAIL  PLAN  OF  VARIABLE  SPEED  MECHANISM 

FIG.  121. — Coal-burning  arrangement,  International  Portland  Cement  Co. 
(B.  F.  Sturtevant  Co.) 

kiln  to  a  proper  temperature  for  the  complete  combustion  of  the  pul- 
verized coal.  The  blast-fans  in  .most  cases,  draw  their  supply  of  air 
directly  from  the  kiln-room.  In  some  plants,  however,  the  inlet  to 
blast-fans  are  connected  with  the  clinker-coolers  or  the  other  parts  of  the 


488 


CEMENTS,  LIMES,  AND  PLASTERS. 


THE   ROTARY   KILN. 


489 


cement  apparatus,  which  have  a  tendency  to  heat  large  volumes  of 
$ir  by  means  of  the  galvanized  steel-  ducts,  thus  insuring  air  at  a  much 
higher  temperature  for  use  as  blast  to  the  injector.  The  air-blast  of 
fans  is  distributed  to  the  several  injectors  by  means  of  galvanized  steel 
piping  J,  usually  located  directly  in  back  of  injectors. 

The  pulverized  coal  as  it  drops  into  injector  is  taken  into  suspen- 
sion by  air-blast  supplied  to  injector  through  blast-piping  J  and 
fed  through  wrought-iron  feed*pipes  K  into  discharge  end  of  kiln. 
The  feed-pipe  usually  enters  kiln  about  3  to  12  inches  below  the  center. 


FIG.  123. — Kirkwood  gas-burner  for  rotary  kiln. 

In  extremely  large  kilns  two  feed-pipes  are  usually  used  so  that  cur- 
rent of  air  containing  the  pulverized  coal  can.  be  blown  into  different 
points  of  the  kiln  at  the  same  time.  The  volume  of  air  admitted  to 
injector  is  regulated  by  blast-gate  L.  The  length  of  the  flame  in  the 
kiln  is  dependent  upon  the  velocity  of  the  aj  r  as  it  leaves  the  feed-pipe. 
Gas-burners  for  rotary  kilns. — Natural  gas  is  at  present  utilized 
as  a  kiln  fuel  at  several  Kansas  plants.  An  Ohio  plant  when  last  visitecj 


490 


CEMENTS,  LIMES,  AND  PLASTERS. 


was  running  some  of  its  kilns  on  natural  gas  and  some  on  producer 
gas.  At  all  these  plants  the  Kirkwood  burner,  shown  in  Figs.  123, 
124,  is  used  in  supplying  gas  to  the  kiln. 

The  Kirkwood  gas-burner  is  manufactured  by  Tate,  Jones  &  Co., 
of  Pittsburg,  Pa.,  under  patents  granted  to  R.  G.  Kirkwood  in  1896. 
It  consists  of  two  concentric  cylindrical  casings,  which  are  bolted  to- 
gether, forming  an  annular  chamber.  A  large  number  of  small  pipes 
are  set  to  form  a  spiral  series,  passing  from  one  side  to  the  other  of  the 
annular  chamber.  These  pipes  are  provided  with  t  a  number  of  fine 
holes,  and  a  nozzle  caps  the  entire  outfit.  Gas  is  introduced  through 
an  opening  into  the  annular  chamber,  from  which  it  passes '  into  the 
small  pipes,  issues  through  the  holes  in  these  pipes  in  a  great  number 
of  fine  jet"  °nd  mixes  with  the  air  which  is  blown  through  the  burner, 


Air  Inlet 
Forced  Draught 
2 "Kirkwood  Patent 
Natural  Gas  Burner 


FIG.  124. — Kirkwood  gas-burner  applied  to  rotary  kiln.     (Tate,  Jones  &  Co.) 

thus  securing  a  proper  mixture  of  air  and  gas  to  be  burned  at  the  noz- 
zle. A  cast-iron  plate  filled  with  asbestos  cement  is  provided  for  bolt- 
ing to  the  front  of  the  kiln  to  receive  the  end  of  the  burner,  and  the 
back  of  the  burner  has  a  projection  into  which  the  air-blast  pipe  is  in- 
troduced. These  burners  are  about  18  inches  in  diameter  and  5  feet 
in  length,  and  are  designed  to  work  efficiently  with  a  gas  pressure  of 
from  3. to  4  ounces  per  square  inch. 

Kiln  linings. — Three  materials  have  been  used  for  kiln  linings; 
cement  clinker,  alumina  brick,  and  magnesia  brick.  A  fourth  will 
probably  be  introduced  in  the  near  future — bauxite  brick. 

Of  these  lining  materials,  the  use  of  alumina  brick  may  be  con- 
sidered to  be  the  standard  American  practice.  In  the  following  tables 
analyses  of  these  products  are  given.  Table  181  contains  analyses  of 
clays  used  in  the  manufacture  of  high-alumina  kiln  brick,  while  analyses 
of  the  brick  are  given  in  Table  182.  Tables  183  and  184  contain  analyses 
of  low-alumina  clays  and  the  resulting  brick,  which  have  been  supplied 
for  rotary-kiln  linings  at  several  plants. 


THE   ROTARY  KILN. 


491 


TABLE  181. 
ANALYSES  OF  HIGH-ALUMINA  CLAYS  USED  FOR  KILN  BRICK. 


1. 

2. 

3. 

4. 

Silica  (SiO2)               

4  338 

44  52 

43  05 

40  30 

Alumina  (A12O3)      .  .  .  .  ,  

40  35 

40  81 

44  60 

45  00 

Iron  oxide  (Fe2O3)  

0  85 

1  03 

2  60 

n  d 

Lime  (CaO)  

0  88 

0  62 

0  40 

n  d 

Magnesia  (MgO)  

0  23 

0  55 

0  20 

n  d 

Carbon  dioxide  (CO2) 

Water 

)    13.41 

12.11 

9.00 

n.  d. 

5. 

6. 

7. 

8. 

Silica  (SiO2)             

40  80 

42  -71 

44  00 

43  52 

Alumina  (A12O3)       

49  00 

38  88 

42  12 

42  18 

Iron  oxide  (Fe2O3)    

n   d 

3  36 

0  86 

0  42 

Lime  (CaO)     

n.  d. 

0  13 

0.24 

0  25 

Magnesia  (MgO) 

n   d 

0  00 

0  10 

0  16 

Carbon  dioxide  (COy)  

1              A 

Water    

f    n.  d. 

15.19 

14.20 

14.31 

1,  2.  Olive  Hill,  Carter  County,  Ky.     Analyses  from  Stowe-Fuller  Co.'s  catalogue,  p.  25£. 
3,  4,  5.  Hayward,  Carter  County,  Ky.     Ironton  Fire-brick  Co. 

6.  Carter  County,  Ky.     Chas.  Taylor's  Sons.     F.  W.  Clarke,  analyst.    Specimen  selected  by  E.  C. 

Eckel. 

7.  Lock  Haven,  Pa.     P.  L.  Hobbs,  analyst.     Stowe-Fuller  Co.'s  catalogue,  p.  26*. 

8.  "          "      ,   "       Crowell  and  Peck,  analysts.     Stowe-Fuller  Co.'s  catalogue,  p.  26£. 


TABLE  182. 
ANALYSES  OF  HIGH-ALUMINA  FIRE-BRICK  FOR  KILNS. 


1. 

2. 

3. 

4. 

Silica  (SiO2)           .          .    . 

54  86 

52  64 

49  70 

54  03 

Alumina  (A12O3)       

I    42.74 

40  45 

Iron  oxide  (Fe2O3)  

44.84 

47  .  86    < 

3.47 

Lime  (CaO)  

1  30 

0  84 

0.80 

0.31 

Magnesia  (MgO)  

0  62 

0.88 

0.80 

tr. 

5. 

6. 

7. 

8. 

9. 

Silica  (SiO2)  

55.22 

54.38 

58.90 

51.95 

56.44 

Alumina  (Al  O3) 

41  51 

41  72 

36.30 

45.01 

35.81 

Iron  oxide  (Fe2O3) 

2  84 

3.20 

2.01 

4.79 

Lime  (CaO) 

1.00 

1.60 

0.04 

n.  d. 

Magnesia  (MgO) 

tr. 

tr. 

0.29 

n.  d. 

1.  2.  "Tyrone"  brick,  Harbison-Walker  Co.     H.  S.  Turner,  analyst. 

3.  Kentucky  Fire  Brick  Co.     H.  S.  Turner,  analyst. 

4.  Ironton  Fire  Brick  Co.     F.  W.  Clarke,  analyst.     Specimen  selected  by  E.  C.  Eckel. 

5.  "          "         "       "       Analysis  quoted  by  manufacturers. 

6.  7.  Christy  Fire  Brick  Co. 

8.  "Munro"  brick,  Stowe-Fuller  Co.     P.  L.  Hobbs,  analyst.     Catalogue,  p.  70. 

9.  Stowe  Fuller  Co.     E.  Davidson,  analyst. 


492 


CEMENTS,  LIMES,  AND   PLASTERS. 


TABLE  183. 
ANALYSES  OF  LOW-ALUMINA  CLAYS  USED  FOR  KILN  BRICK. 


Silica  (SiO2) 

Alumina  (A12O3) 

Iron  oxide  (Fe2O3) .  . . 

Lime  (CaO) 

Magnesia  (MgO) 

Alkalies  (K2O,Na2O). 
Carbon  dioxide  (CO2). 


55.0 
30.0 
tr. 
tr. 
tr. 
2.0 


vydi  wii  U.IVJA.IU.C   \\^\s2J t        -lo    r\ 

Water ! J    13'° 


56.02 
28.26 
2.18 
2.04 
0.95 
n.  d. 

10.50 


TABLE  184. 
ANALYSES  OF  LOW-ALUMINA  BRICK,  FURNISHED  AS  KILN  BRICK. 


i. 

2. 

3. 

4. 

5. 

Silica  (SiO2)  

62  58' 

63  94 

61.20 

62  92 

72  71 

Alumina  (A12O3)  

25  62 

30.14 

29  05 

30  47 

22  24 

Iron  oxide  (Fe2O3)  

4  76 

3.70 

5.55 

4.61 

4  47 

Lime  (CaO)     

6  05 

2.20 

n.  d. 

n.  d. 

0  94 

Magnesia  (MgO) 

0  85 

tr 

n   d 

n   d 

0  42 

The  manner  in  which  these  bricks  are  set  in  lining  kilns  is  shown 
in  Figs.  125  and  126. 

Actual  fuel  consumption  and  output. — In  the  following  chapter 
the  question  of  heat  requirements  and  heat  distribution  in  the  rotary 
kiln  will  be  discussed  in  considerable  detail.  At  present  it  is  only 
necessary  to  state  that  in  burning  a  dry  mixture  to  a  clinker,  practi- 
cally all  of  the  heat  consumed  in  the  operation  will  be  that  required 
for  the  dissociation  of  the  lime  carbonate  present  into  lime  oxide  and 
carbon  dioxide.  Driving  off  the  water  of  combination  that  is  chem- 
ically held  by  the  clay  or  shale,  and  decomposing  any  calcium  sulphate 
(gypsum)  that  may  be  present  in  the  raw  materials,  will  require  a  small 
additional  amount  of  heat.  The  amount  required  for  these  purposes 
is  not  accurately  known,  however,  but  is  probably  so  small  that  it  will 
be  more  or  less  entirely  offset  by  the  heat  which  will  be  liberated  during 
the  combination  of  the  lime  with  the  silica  and  alumina.  We  may, 
therefore,  without  sensible  error  regard  the  total  heat  theoretically 
required  for  the  production  of  a  barrel  of  Portland  cement  as  being 
that  which  is  necessary  for  the  dissociation  of  450  Ibs.  of  lime  carbonate. 
With  coal  of  a  thermal  value  of  13,500  B.T.U.  per  pound,  burned  with 
only  the  air-supply  demanded  by  theory,  this  dissociation  would  require 
about  25J  Ibs.  of  coal  per  barrel  of  cement,  a  fuel  consumption  of  only 
6J  per  cent  on  the  weight  of  cement  produced. 

In  actual  practice,  however,  the  heat  required  for  cement  produc- 


THE   ROTARY  KILN. 


oa  "•* "'     ^ 


I 

CL 


~     fe: 


o     s  R  F 


?ii 


3    ° 

^    5- 


^ 

o  w  g 

8  g.H 
* 


494  CEMENTS,  LIMES,  AND  PLASTERS. 

tion  is  immensely  greater  than  that  demanded  by  theory.  This  is  due 
to  the  fact  that  heat  is  wasted  or  lost  in  various  ways  during  the  process 
of  burning  in  the  rotary  kiln.  The  more  important  losses  of  heat  occur 
from  the  fact  that  the  stack-gases  and  clinker  are  usually  discharged 
at  high  temperatures;  that  the  air-supply  injected  into  the  kiln  is  always 
greater,  and  usually  much-' greater,  ^han  that  theoretically  necessary; 
and  that  much  heat  is  lost  by  radiation  from  the  exposed  surface  of 
the  kiln. 

Sixty-foot  rotary  kilns  are  nominally  rated  +  at  a  production  of 
200  barrels  per  day  per  kiln.  Even  on  dry  materials  and  with  good 
coal,  however,  such  an  output  is  rarely  attained.  Normally  a  60-foot 
kiln  working  on  a  dry  mixture  will  produce  from  140  to  180  barrels 
of  cement  per  day  of  twenty-four  hours.  In  doing  this,  if  good  coal  is 
used,  its  fuel  consumption  will  commonly  be  from  120  to  140  Ibs.  of 
coal  per  barrel  of  cement,  though  it  may  range  as  high  as  160  Ibs.,  and, 
on  the  other  hand,  has  fallen  as  low  as  90  Ibs.  An  output  of  160  barrels 
per  day,  with  a  coal  consumption  of  130  Ibs.  per  barrel,  may  therefore 
be  considered  as  representing  the  results  of  fairly  good  practice  on  dry 
materials.  With  longer  kilns,  however,  much  better  results  are  obtained, 
as  will  be  noted  later. 

In  dealing  with  a  wet  mixture,  which  may  carry  anywhere  from 
30  to  70  per  cent  of  water,  the  results  are  more  variable,  though  always 
worse  than  with  dry  materials.  In  working  a  60-foot  kiln  on  a  wet 
material,  the  output  may  range  from  80  to  140  barrels  per  day,  with 
a  fuel  consumption  of  from  150  to  230  Ibs.  per  barrel.  Using  a  longer 
kiln,  partly  drying  the  mix,  and  utilizing  waste  heat  will,  of  course, 
improve  these  figures  materially. 

When  oil  is  used  for  kiln  fuel,  it  may  be  considered  that  one  gallon 
of  oil  is  equivalent  in  the  kiln  to  about  10  Ibs.  of  coal.  The  fuel  con- 
sumption, using  dry  materials,  will  range  between  11  and  14  gallons 
of  oil  per  barrel  of  cement;  but  the  output  per  day  is  always  some- 
what less  with  oil  fuel  than  where  coal  is  used. 

Natural  gas  in  the  kiln  may  be  compared  with  good  Pennsylvania 
or  West  Virginia  coal  by  allowing  about  20,000  cubic  feet  of  gas  as 
equivalent  to  a  ton  of  coal.  This  estimate  is,  however,  based  upon 
too  little  data  to  be  as  close  as  those  above  given  for  oil. 

The  figures  given  in  Table  185,  below,  are  believed  to  be  entirely 
reliable.  They  are  of  interest  as  showing  what  can  actually  be  expected 
from  kilns  under  average  management,  as  distinguished  from  the 
expectations  which  embellish  company  prospectuses  and  the  reports 
of  "cement  experts."  With  the  exception  of  A,  B,  and  J,  the  mills 


THE  ROTARY  KILN. 


495 


here  listed  are  good  average  plants.  Mill  results  A  and  B  are  from 
one  of  the  best  of  the  Lehigh  district  plants,  while  J  is  perhaps  the 
best  of  all  marl-plants.  Excluding  these  three,  it  will  be  seen  that  the 
production  per  kiln  per  day  is  considerably  lower,  and  the  fuel  con- 
sumption much  higher,  than  is  usually  allowed  for. 

TABLE  185. 
ACTUAL  OUTPUT  AND  FUEL  CONSUMPTION  AT  VARIOUS  PLANTS. 


Mill. 

Materials. 

Process. 

Per  Cent 
of  Water 
in  Mixture. 

Length 
of  Kiln, 
Feet. 

Output 
per  Day, 
Barrels. 

Coal  per 
Barrel, 
Pounds. 

A 

Cement  rock 

Dry 

60 

225 

105-113 

B 

it          t  ( 

80 

260 

95-100 

c 

tt          « 

60 

160-180 

109-175 

D 

tt          (i 

150 

350 

62-75 

E 
F 

Limestone  and  shale.  .... 

1  1            1  1       a 

0. 

60 
60 

170 
? 

160 
105 

G 

«            ((       (  ( 

60 

? 

122 

H 

I 
J 

it            «       tt 
ii            tt       « 

Marl  and  clay  .....  ..... 

Wet 

60 

60 
60 
110 

185 
170 
135 

130 
135 
? 

K 

Marl  and  shale 

50 

70 

145 

? 

L 

1  1       tt       1  1 

60 

60 

85 

? 

M 

1  1       1  1       t  < 

50 

60 

120 

? 

N 

Marl  and  clay 

30 

60 

125 

173 

o 

1C             t  t             (I 

35 

60 

100 

160 

p 

It          It          11 

65 

60 

80 

180-210 

Q 

Limestone  and  clay 

35 

60 

ICO 

200-220 

R 

t  <            «  «       it 

30 

60 

140 

180 

Using  the  figures  above  given  as  a  basis,  Table  185  has  been  con- 
structed to  give  some  idea  of  what  may  fairly  be  expected  from  kilns 
of  various  length  working  on  different  raw  materials. 

TABLE  186. 
AVERAGE  OUTPUT  AND  FUEL  CONSUMPTION. 


Process. 

Raw  Materials. 

Length 
of  Kiln, 
Feet. 

Output  per  Kiln 
per  Day,  Barrels. 

Coal  Consumption 
per  Kiln  per 
Barrel,  Pounds. 

Range. 

Aver- 
age. 

Range. 

Aver- 
age. 

Wet 
< 

«  . 

Dry 
« 

i 

Marl  and  clay  

60 
80-90 
110* 
60 
60 
80 
150* 

60-140 
80-150 
135 
150-200 
180-250 
225-300 
375 

85 
100 
135 
160 
200 
260 
375 

150-250 
140-220 
150 
90-170 
85-160 
85-120 
65 

200 
160 
150 
130 
115 
110 
65 

<  «       1  1      tt 

Limestone  and  clay 

Cement  rock  and  limestone.  . 
t  i          1  1      tt'       it 

it          1  1       «           « 

Based  on  only  one  plant. 


496  CEMENTS,  LIMES,  AND  PLASTERS. 

The  differences  in  composition  between  Portland-cement  mixtures 
are  very  slight  if  compared,  for  example,  to  the  differences  between 
various  natural  cement  rocks.  But  even  such  slight  differences  as 
do  exist  exercise  a  very  appreciable  effect  on  the  burning  of  the  mix- 
ture. Other  things  being  equal,  any  increase  in  the  percentage  of  lime 
in  the  mixture  will  necessitate,  a  higher  temperature  in  order  to  get 
an  equally  sound  cement.  A  mixture  which  will  give  a  cement  carry- 
ing 59  per  cent  of  lime,  for  example,  will  require  much  less  thorough 
burning  than  would  a  mixture  designed  to  give  a  cement  with  01 
per  cent  of  lime. 

With  equal  lime  percentages,  the  cement  carrying  high  silica  and 
low  alumina  and  iron  will  require  a  higher  temperature  than  if  it  wrere 
lower  in  silica  and  higher  in  alumina  and  iron.  But,  on  the  other  hand, 
if  the  alumina  and  iron  are  carried  too  high,  the  clinker  will  ball  up 
in  the  kiln,  forming  sticky  and  unmanageable  masses. 


CHAPTER  XXXIV. 
HEAT  CONSUMPTION  AND   HEAT   UTILIZATION. 

AN  investigation  of  the  ways  in  which  the  heat  supplied  to  the  kiln 
is  utilized  and  wasted  is  a  matter  of  both  theoretical  and  practical 
importance.  It  can  readily  be  seen  that  until  some  idea  can  be  gained 
of  the  relative  importance  of  the  different  causes  of  loss  of  heat,  little 
can  be  done  to  prevent  this -waste  or  to  utilize  the  heat  so  dispersed. 
An  exact  knowledge  of  the  distribution  of  the  total  heat  supplied  to 
the  kiln  would  therefore  be  of  great  service  to  the  manufacturer. 

In  the  present  chapter  the  writer  has  attempted  to  present  such 
data  on  this  subject  as  are  available,  and  to  discuss  them  in  such  a 
way  as  to  bring  out  the  relations  of  the  various  factors  in  the  problem 
of  heat  distribution.  Attention  is  drawn,  whenever  necessary,  to  any 
doubts  as  to  the  accuracy  of  the  data  employed. 

Theoretical  Heat  Requirements. 

In  order  that  a  raw  mixture  shall  be  converted  into  cement  clinker 
in  the  kiln,  sufficient  heat  must  be  applied  to  bring  about  the  necessary 
physical  and  chemical  changes.  The  purposes  for  which  this  heat  is 
required  are: 

(1)  Evaporation  of  the  water  of  the  mix. 

(2)  Decomposition  of  the  clay. 

(3)  Dissociation  of  sulphates. 

(4)  Dissociation  of  carbonates. 

(5)  Heating  the  mix  to  clinkering  point. 

Of  these  five  requirements,  it  is  to  be  noted  that  the  first  four  are 
for  accomplishing  chemical  changes,  and  that  the  heat  supplied  for 
these  purposes  is  entirely  absorbed  in  doing  chemical  work.  This  is 
not  true  with  regard  to  the  fifth  requirement — the  heating  of  the  mix — 
for  the  heat  used  for  this  purpose,  after  it  has  once  served  its  purpose, 
still  remains  as  sensible  and  therefore  utilizable  heat.  Most  of  it,  in  fact, 
passes  out  in  the  clinker. 

In  a  perfect  kiln  the  only  heat  required  would  be  that  sufficient 
to  accomplish  the  first  four  operations  in  the  above  list,  for  in  a  theo- 
retically perfect  burning  device  there  would  be  no  loss  by  radiation, 

497 


498 


CEMENTS,  LIMES,  AND  PLASTERS. 


the  stack-gases  would  be  cold,  and  the  clinker  heat  would  be  utilized. 

In  actual  practice,  however,  a  very  large  amount  of  heat  is  carried 
out  with  the  stack-gases,  radiated  from  the  exposed  surfaces  of  the 
kiln,  and  carried  out  in  the  hot  clinker. 

Heat  utilized  in  evaporation  of  water. — It  is  obvious  that  any  water 
contained  in  the  charge  must  be  evaporated,  and  the  steam  thus  formed 
must  be  raised  to  the  temperature  of  the  stack-gases.  It  is  here  that 
the  great  difference  in  economy  between  the  dry  and  wet  methods 
of  mixing  is  shown. 

In  the  dry  method  the  total  water  (mechanically  held  and  combined) 
contained  in  the  charge  will  rarely  rise  above  2^  per  cent,  of  which 
about  2  per  cent  may  be  combined  in  the  clay  and  ^  per  cent  held 
mechanically.  The  products  in  the  dry  process,  when  working  with 
a  60-foot  kiln,  issue  from  the  stack  at  a  temperature  of  about  1500°  F. 
=  815°  C.  When  a  longer  kiln  is  employed,  and  the  trend  of  present 
practice  seems  to  be  in  the  direction  of  100-foot  or  even  longer  cylin- 
ders, the  stack  temperatures  will  be  correspondingly  reduced.  With 
a  100-foot  kiln  it  seems  probable  that  they  can  be  kept  down  at 
least  to  1000°  F. 

In  the  wet  process,  on  the  other  hand,  the  charge  usually  contains 
about  60  per  cent  of  water,  though  in  a  few  plants  this  is  kept  down 
to  30  or  40  per  cent.  The  stack  temperatures  are,  however,  much 
lower  than  m  the  dry  process,  ranging  from  about  800°  F.  with  a  60-foot 
kiln  to  450°  or  so  in  a  100-foot  kiln.  This  partly  counterbalances  the 
loss  of  heat  due  to  the  high  percentage  of  water. 

Using  these  data  as  a  basis,  Table  187  has  been  prepared  to 
show  the  amount  of  heat  required  for  simply  evaporating  the  water 
from  three  different  types  of  mixture,  in  kilns  of  two  different  lengths. 

TABLE  187. 
HEAT  USED  IN  EVAPORATION  OF  WATER. 


Process. 

Kiln 
Length, 
Feet. 

Stack 
Temperature. 

Per  Cent 
Water. 

Pounds 
Water  per 
Barrel. 

B.  T.  U.  Used  per 
Barrel. 

Dry 

60 

1500°  F 

2* 

15 

23  367 

«y" 

100 

1000°  F 

2* 

15 

21  079 

Wet  . 

60 

800°  F 

30 

272 

365  650 

<  ( 

100 

450°  F 

30 

272 

336  630 

<  < 

60 

800°  F  • 

60 

900 

1  209  870 

i  « 

100 

450°  F 

60 

900 

1  113  840 

Heat  utilized  in  decomposition  of  clay. — An  unknown,  though  prob- 
ably small,  amount  of  heat  is  required  to  dissociate  the  clayey  portion 
of  the  mix.  No  exact  data  on  this  point  are  known  to  the  writer,  but 


HEAT  CONSUMPTION  AND  HEAT  UTILIZATION.  499 

the  amount  so  utilized  will  probably  be  covered  if  we  estimate  all  the 
water  which  is  really  chemically  combined  with  the  clay  as  being  mechan- 
ically held  water.  This  course  has  been  followed  in  the  present  esti- 
mates. On  this  assumption,  even  a  dry  mix  will  carry  about  2J  per  cent 
of  water,  and  this  amount  has  been  accordingly  allowed  for  in  the 
previous  paragraph  and  in  Table  187. 

Heat  utilized  in  dissociation  of  sulphates. — A  certain  amount  of  heat 
is  taken  up  in  dissociating  any  lime  sulphate  (gypsum)  present  in  the 
raw  mix.  Newberry  has  taken  this  as  requiring  1890  B.T.U.  per  pound 
of  SOs.  In  marl  plants  the  percentage  of  sulphates  present  may 
rise  to  notable  quantity,  but  in  most  other  plants  they  are  negligible. 
In  the  present  discussion  the  assumptions  will  be  made  that  the 
average  dry  mix  carries  0.3  per  cent  of  sulphur  trioxide,  and  that 
the  usual  wet  mix  may  carry  1  per  cent.  The  total  amount  of  heat 
required  for  the  dissociation  of  sulphates  will  therefore  be: 

Dry  mix 600  lbs.X0.3%Xl890=   3,402  B.T.U.  per  barrel 

Wet  mix "    "   X  1.0%  X 1890  =  11, 340       "        "        " 

Heat  utilized  in  dissociation  of  carbonates. — The  most  important 
heat  requirement  by  far  is  that  for  the  dissociation  of  the  carbonates 
of  the  charge. 

The  values  assumed  by  Richards  for  the  dissociation  requirements 
of  the  two  carbonates  are: 

Liberation  of  1  kilo  CO2  from  CaCO3  =  990  calories. 

'•  1    "    CO2     "     MgCO3  =  407       " 

These  are  referred  to  Berthelot.  They  correspond  respectively  to 
the  two  values  of: 

Dissociation  of  1  pound  CaCO3 requires  584  B.T.U. 
"  1      "      MgC08      "        381       " 

These  values  will  be  accepted  in  the  following  calculations  for 
the  sake  of  uniformity,  though  Ostwald  *  quotes  from  Thomsen  a 
value  corresponding  to  765  B.T.U.  for  the  dissociation  of  1  Ib.  of 
lime  carbonate.  If  this  latter  value  were  accepted,  the  quantities 
given  in  the  table  below  (188)  should  be  reduced  about  2J  per  cent. 
Other  values  for  these  dissociation  constants  have  been  quoted  by 
various  authorities,  with  a  much  wider  range,  but  for  the  present 
purpose  those  first  noted  will  be  satisfactory  enough. 

Temperature  required  for  clinkering. — Widely  differing  statements 
have  been  made  as  to  the  temperature  required  in  order  to  clinker  the 
average  Portland-cement  mixture. 

Carpenter,   in   testing   the   Cayuga   plant   noted   later,   determined 

*  Lehrbuch  der  allgemeinen  Chemie,  vol.  II,  pt.  1,  p.  272. 


500 


CEMENTS,  LIMES,  AND  PLASTERS, 


TABLE  188. 
HEAT  USED  IN  DISSOCIATION  OF  CARBONATES  PER  ^BARREL  CEMENT. 


Percentage 
MgO  in 
Mixture. 

Percentage  of  Lime  (CaO)  in  Mixture. 

40%. 

41%... 

42%. 

43%. 

44%.  " 

45%.    . 

0 

:    1%  -.-'.   i 

•      2% 

3% 
4% 

B.T.U. 
333,234 
:  338,362 
342,758 
347,154 
351,550 

B.T.U. 
342,144 
347',272 
351,668 
356,064 
360,460 

B.T.U. 
351,054 
-  .356,182 
360,578 
364,974 
369,370 

B.T.U. 
359,964 
-  365,092 
369,488 
373,884 
378,280 

B.T.U- 

368,874 
374,002 
378,398 
*•  382,794 
387,190 

B.T.U. 
377,784 
382,912 
387,308 
391,704 
396,100 

:  the   kiln   temperature   by   optical   methods.     The   temperature   in   the 

j  kiln  when  .working  under  best  conditions,  as  determined  by  the  "Noel 

j  optical  pyrometer,  varied  from  2250°  F.  near  the  discharge'  'end1  to  2950° 
F.  about  20  feet  from  the  lower  end,  and  about  1800°  F.  at  -ihe:upper 
end.  The  temperature  in  the  burning  zone  seemed  to  average  about 
2850°  F;,  and  the  temperature  of  the  entire  kiln  on  thejnside  seemed 

-  to  average  nearly  2500°  F. 

-  -For  ordinary  purposes  of  calculation,  it  may  be  assumed  that  1400°— 
1500°  C.,  or  2500°-2700°  F.,  is  about  the  necessary  temperature* in  rotary 

'  -kilns  under  present  'conditions  for  an  average  mixture'.'  'Variations 
in  the  composition  of  the  mixture  would,  of 'course;  change  the  clinker- 
ing  point — for  a  low-limed  high-alumina  mix  will  clinker  at  a  consider- 
ably, lower  temperature  than  will  a  mix  high  in  lime  and  silica. 

It  is  also  true  that  to  a  certain  degree  longer  exposure 'to  the  heat 
will  be  equivalent  in  effects  to  higher  temperature.  In  stationary 
kilns,  for  example,  where  the  charge  may  be  exposed  for  days  to  the 
heat,  the  requisite  temperature  is  much  less  than  in  the  modern  rapid 

'practice  with  the  rotary  kiln. 

Heat  utilized  in  heating  the  mix. — One  of  the  important  uses  of 
the  kiln  heat  is  in  simply  heating  the  mix  up  to  the  point  at  which  it 

:  will  clinker.  Fortunately,  this  can  be  determined  with  sufficient  ac- 
curacy for  all  practical  purposes. 

Whatever  the  percentage  of  the  water  present,  the  dry  portion  "of 
the  mix  will  be  about  600  Ibs.  for  each  barrel  of  cement.  This  600  Ibs. 
of  material  must  be  raised  from  the  temperature  of  the  air— say  60°  F. 
— to  about  1300°  F.  At  this  latter  temperature  the  carbon  dioxide, 

'  sulphur  trioxide,  etc.,  will  have  been  driven  off;   and  this  will  reduce 
..the  weight  to  380  Ibs.     This  380  Ibs.  of  quicklime  and  clay  must  now 
be  raised  to  a  temperature  of  about  2600°  F.,  at  which  clinkering.  will 
take  place. 


HEAT  CONSUMPTION  AND   HEAT  UTILIZATION. 


501 


Assuming  that  the  above  data  are  substantially  correct,  and  that 
the  specific  heat  of  the  mix  is  ab'out  0.22,  the  heat  required  for  the  simple,, 
heating  of  the  mix  to  the  clinkering  point  can  be  calculated  ass  follows: 

'•".  Per  Barrel 

B.T.U. 

600  Ibs.  mix  heated       60°  to  1300°,  spec,  heat  0.22  =  1260X0.22X600  =  166,320 
380     "        "         "        1300°  to  2600°,    "       "      0.22  =  1300 X0*;22x 380 -108,680 

Total  heat  required,  B,T.U., ."..........;... 275,000 

This  estimate  is  probably  aboypjwhal  is  actually  required,  for  the 
temperatures,  weights  and  specific  ..heat  have  all  been  taken  on  the 
safe  side.  The  actual  heat  requirements  are  probably  close  to  250,000 
B.T.U.  for  this  part  of  the  operation. 

In  running  an  actual  test  of  a  kiln  this  quantity  could  tie  checked 
roughly  by  the  amount  of,  heat  contained  in  the  clinker  as  it  leaves 
the  kiln.  In  other  words,  a  barrel  of,  clinker  carries  out  ..with  it  almost 
as  much  heat  as.  was  required  to  clinker  the  raw  mix  for  that  barrel. 

>As  pointed  out  on  a  previous ...  page  (p.  497),  the.  heat/  required  for 
bringing  the  mix  up  to  "the  clinkering  point"  is  not  "utilized -in  causing 
chemical  changes,  .and  can  therefore  be  utilized. again.  In  this" 'respect 
it  differs  from  the  neat  required  for  dissociating  the  carbonates  and 
sulphates,- decomposing  the  clay,  etc.— for  in '  these  _  cases'  the'  heat 
is  absorbed  in  doing  chemical  work  and'  cannot  be  regained.  For 
this  reason  it  will  be  convenient  to  omit,  .from  the  total  .thermal  re- 
quirements, the  heat  used  in  heating  the  mix  up  to  the  clinkering  point; 
and  to  consider  it  rather  in  its-  outgoing  form  as  heat  carried '/put  by  the 
clinker. 

Total  heat  requirements. — The  data  given  in  preceding  paragraphs 
may  now  be  conveniently  summed  up  as  in  the  table  below.  The  basis 
for  the  various  figures  may  be  seen  by  referring  back  to  the  upper  pages. 

TABLE  189. 
THEORETICAL  HEAT  REQUIREMENTS  IN  B.T.U.  PER  BARREL. 


Process             

Dry 

Dry 

Semi-wet 

Wet' 

Length  of  kiln     •.......'....... 

60  ft. 

•  100  ft. 

60  ft. 

•    106  ft. 

Water  in  mix  '  •. 

2\°7 

2£% 

30%  *i 

--60%- 

Stack-gases  

1500°  F. 

1000°  F. 

800°  F. 

•-450-°F; 

Evaporation  of  water 

B.T:U. 
23,367 

B.T.U. 
21,079 

B.T.U. 
365,650 

B.T.U. 
1,113,840 

Dissociation  of  sulphates                .      , 

3,402 

3402 

11,340 

11,340 

Dissociation  of  carbonates            

369,488 

369,488 

369,488 

369,488 

Total  heat  required 

396,257 

393,969 

746,478 

Ir494,668 

Coal  theoretically  necessary,  Ibs.  per  bbl.  .  . 
Coal  actually  used,  Ibs.  per  bbl  

28 
120 

28 
90- 

53    ' 
46Q:   '>: 

107 
150 

502 


CEMENTS,  LIMES,  AND  PLASTERS. 


Heat  Losses  in  Practice. 

In  practice  with  the  rofary  kiln,  there  are  a  number  of  distinct  sources 
of  loss  of  heat,  which  result  in  a  fuel  consumption  immensely  greater 
than  the  theoretical  requirements  given  above.  The  more  important 
of  these  sources  of  loss  are  the  following: 

(1)  The  kiln  gases  are  'discharged  at  a  temperature  much  above 
that  of  the  atmosphere,  ranging  from  300°  F.  to  2000°  F.,  according 
to  the  type  of  materials  used  and  the  length  of  the  kiln.  % 

(2)  The  clinker  is  discharged  at  a  temperature  varying  from  200°  F. 
to  2500°  F.,  the  range  depending  as  before  on  materials  and  length 
of  the  kiln. 

(3)  The  air-supply  injected  into  the  kiln   is   always   greater,  and 
usually  very  much  greater,  than  that  required  for  the  perfect  combus- 
tion of  the  fuel,  and  the  available  heating  power  of  the  fuel  is  thereby 
reduced. 

(4)  Heat  is  lost  by  radiation  from  the  ends  and  exposed  surfaces 
of  the  kiln. 

(5)  The  mixture  in  plants  using  a  wet  process  carries  a  high  per- 
centage of  water,  which  must  be  driven  off. 

It  is  evident,  therefore,  that  present-day  working  conditions  serve 
to  increase  greatly  the  amount  of  fuel  actually  necessary  for  the  pro- 
duction of  a  barrel  of  cement  above  that  required  by  theory. 

The  extent  of  these  losses,  compared  with  the  amount  of  heat  ac- 
tually used,  can  be  seen  from*  the  following  comparison  of  various 
estimates  and  tests,  all  relating  to  a  60-foot  kiln  on  dry  material: 

TABLE  190. 
UTILIZATION  AND  LOSSES  OF  HEAT  IN  ROTARY  KILNS. 


Richards. 

Carpenter. 

Helbig. 

Newberry. 

Eckel. 

Average. 

Total  heat  supplied    to 
kiln         

Per  Cent. 
100  00 

Per  Cent. 
100  .  00 

Per  Cent. 
100.00 

Per  Cent. 
100  .  00 

Per  Cent. 
100  00 

Per  Cent. 
100  00 

Heat  utilized  

19  75 

23  .  43 

25.56 

25.54 

23.59 

23  57 

Heat  lost  in  clinker      .... 

10  72 

14  09 

12  01 

15.47 

13  07 

Heat  lost  in  stack-gases  . 
Heat  lost  by  radiation.  .  . 
Minor  heat  losses  

72.46 
-4.46 
1  54 

47.42 
15.07 
0  00 

50.24 
4.88 
7  31 

43.62 
15.38 
0  00 

76.41 

53.43 

7.72 
2  21 

Heat  carried  out  in  flue-dust. — A  considerable  amount  of  fine  dust 
is  carried  out  of  the  kiln  by  the  hot  gases.  This  flue  dust,  deposited 
wherever  the  air  current  is  checked,  may  amount  to  from  J  to  3  per 
cent  of  the  total  amount  of  mix  charged  to  the  kiln. 


HEAT  CONSUMPTION  AND  HEAT  UTILIZATION.  503 

The  composition  of  the  flue-dust  is  a  matter  of  considerable  indus- 
trial importance.  It  is  composed  of  the  lighter  and  finer  particles  of 
the  cement  mix  and  the  ash,  plus  a  certain  amount  of  material  deposited 
from  the  stack-gases.  This  last  factor  includes  in  some  cases  a  large 
percentage  of  alkali  salts,  whose  recovery  has  been  suggested  as  a  profit- 
able by-product.  (See  p.  510.) 

Sources  of  Heat-supply. 

To  counterbalance  the  heat  utilized  and  the  heat  wasted,  as  above 
noted,  heat  is  always  supplied  to  the  kiln  from  two  sources,  and  occa- 
sionally from  two  other  sources.  The  invariable  sources  of  supply 
are: 

(1)  A  large  and  well-known  supply  is  derived  from  the  combustion 
of  the  fuel  fed  to  the  kiln. 

(2)  A  smaller    and   very  poorly  defined  supply  is  obtained  from 
exothermic  chemical  combinations  which  take  place  in  the  kiln  during 
clinker  ing. 

Supplies  from  these  two  sources  are  necessarily  received  in  every  kiln. 
In  addition,  however,  heat  may  be  supplied  from 

(3)  Regeneration  of  the  clinker  heat. 

(4)  Utilization  of  the  heat  in  the  stack-gases. 

Heat  supplied  by  combustion  of  fuel. — The  most  important  source 
of  the  heat  supplied  to  the  kiln  is,  of  course,  the  burning  of  the  fuel 
injected  into  it.  This  can  be  estimated  accurately  enough,  for  any 
given  kiln,  if  the  composition  of  the  coal  and  the  amount  of  coal  used 
per  barrel  of  cement  are  known.  It  must  be  borne  in  mind,  however, 
that  any  defects  in  the  coal-feeding  arrangements,  or  deficiencies  in 
the  fineness  of  coal  grinding,  should  not  properly  be  charged  against 
the  efficiency  of  the  kiln,  but  against  the  efficiency  of  the  superintendent. 
In  calculating  the  heat  supplied  to  the  kiln  by  combustion  of  fuel  the 
assumption  is  always  made  that  the  coal  is  ground  as  fine  as  is  econom- 
ically possible,  and  that  the  injecting  apparatus  gives  perfect  combus- 
tion. Actually  we  know  that  neither  of  these  assumptions  is  ever  quite 
justified  and  that  in  some  mills  both  are  very  incorrect. 

If  the  best  bituminous  coal  from  western  Pennsylvania  or  West 
Virginia  be  used,  a  theoretical  heating  value  of  14,000  B.T.U.  per  Ib. 
may  be  assumed :  but  the  coals  used  in  practice  often  fall  very  far  short 
of  this.  Such  a  coal,  used  at  the  rate  of  120  Ibs.  per  barrel  of  cement, 
would  give  a  heat  supply  of  1,680,000  B.T.U.  per  barrel.  This  is  prob- 
ably about  equal  to  the  average  practice  with  60-foot  kilns  on  a  dry 
mixture  of  limestone  and  clay.  With  longer  kilns,  under  specially 


504  CEMENTS,  LIMES,  AND  PLASTERS 

favorable  circumstances,  a  fuel  consumption  of  90  Ibs.  per  barrel  may 
be  expected,  corresponding  to  a  heat  supply  of  1,260,000  B.T.U.  per 
barrel.  With  the  wet  process  a  fuel  consumption  of  160  Ibs.  per  barrel 
is  rather  better  than  the  average.  This  corresponds  to  a  heat  supply 
of  2,240,000  B.T.U.  per  barrel.  These  three  estimates  have  therefore 
be  used  in  making  up  the  summary  ^able. 

Heat  supplied  by  chemical  combinations. — It  is  undoubtedly  true 
that  a  considerable  quantity  of  heat  must  be  liberated  when  the  lime 
and  magnesia  combine,  at  the  clinkering  temperature,  with  the  silica, 
.alumina  and  iron  oxide,  and  that  in  this  way  considerable  heat  is  added 
to  that  derived  from  the  fuel.  Unfortunately,  however,  we  have  no 
very  definite  knowledge  as  to  the  exact  chemical  combinations  which 
take  place  during  clinkering,  and  lacking  such  knowledge  any  estimate 
of  the  amount  of  heat  thus  liberated  must  be  considered  as  merely  a 
wild  guess. 

Both  Helbig  and  Richards,  in  the  papers  previously  cited,  have 
quoted  Berthelot  on  this  point  as  giving  the  following  data  for  the  heat 
.liberated  during  this  combination. 

1  kilogram  lime  (GaO)  liberates. 530  calories 

1         ' '         magnesia  (MgO)  liberates.  .... 827       ' '   , 

These  figures,  changed  into  English  measures,  are: 

1  pound  lime  (CaO)  liberates . . 954  B.T.U. 

1      "      magnesia  (MgO)  liberates.  . , 1489  :   rt 

For  convenience  these  figures  might  be  adopted  in  discussion,  but  both 
the  reader  and  experimenter  must  bear  in  mind  that  they  represent 
very  doubtful  assumptions,  and  are  accepted  merely  because  no  better 
data  are  obtainable.  In  the  present  discussion  of  the  subject  no  esti- 
mate of  this  type  will  be  used. 

Heat  derived  from  the  clinker. — A  large  part  of  the  heat  carried  out 
in  the  hot  clinker  may  be  used  to  heat  the  incoming  air.  In  Carpenter's 
experiments  a  little  less  than  half  of  the  clinker  heat  was  thus  utilized, 
but  other  experimenters  have  claimed  80  to  90  per  cent  efficiency  for 
various  types  of  clinker-heat  regenerators.  The  amount  of  heat  thus 
returned  to  the  kiln  might  therefore  vary  from  90,000  to  175;000  B.T.U. 
per  barrel  of  cement. 

Heat  derived  from  the  stack-gases. — Heat  may  also  be  taken  from 
the  stack-gases  and  used  to  heat  either  the  raw  material  or  the  air- 
supply.  Usually,  however,  stack-gas  heat  when  utilized  is  used  in  the 
power  department  of  the  mill,  rather  than  in  the  kiln. 


HEAT  CONSUMPTION  AND  HEAT  UTILIZATION. 


505 


Estimates  and  Tests  of  Heat  Distribution. 

Various  estimates  of  the  heat  requirements  of  cement-manufacture 
have  been  presented  by  different  authors,  and  several  actual  tests  have 
been  made  of  heat  distribution  in  the  rotary  'kiln.  The  principles  on 
which  these  calculations  are  based  have  been  discussed  in  the  preceding 
pages,  and  the  estimates  and  tests  in  question  will  now  be  presented 
for  comparison. 

Newberry's  estimates. — Some  years  ago  Prof.  Newberry  published 
a  discussion  of  the  question  of  fuel  consumption  which  leaves  little  to 
be  desired  even  in  spite  of  recent  changes  in  rotary  practice.  His 

Tesuits  are  summarized  in  Table   191. 

.    .      ,,.t  . 

TABLE  191. 
NEWBERRY'S  ESTIMATES  ON  HEAT  DISTRIBUTION  IN  KILNS. 


.- 

Vertical  Kiln. 

Rotary  Dry  Pro'cess. 

Rotary  Wet  Process. 

B.T.U. 

Per  Cent. 

B.TrUv 

Per  Cent. 

B.T.U. 

I 

Per  Cent. 

Evaporation  of  water.  .  .  .  .  . 

14,498 
11,340 
344,250 

3.7 

2,8 
88.9 

20,832 
11,340 
344,250 
.  228,000 

.  !  24,  480 

3.3 

1.8 
54.7  ; 
36.3) 

3V&J; 

-827,424 
11,310 
344,250 

.213,312 

59.3 

0.8. 
24.6 

15.3 

Liberation  of  sulphates.  .... 
Dissociation  of  carbonates.  . 
Heating  iof  mix  and  clinker 
Heating  of  CO2  and  SO3  from 

mix    '•• 

16,646 

4.6 

Total  B.T.U.  required  
Lbs.  coal  required  per 
bbl.  ,  theoret.  air-s'ply 
'Lbs.  coal  required   per 
bbl.,  50%  excess  air.  . 
Lbs.  coal  actually  used 
in  practice;  

386,734 
31.0 
32.1 
42-46 

100,0 

! 

628,902 
66.9 
82  2 

100,0  • 

1,396,326 
120.0 
128. 
150-160 

100.0 

110-120 

Helbig's  estimates. — Very  recently  Mr.  A.  B.  Helbig  has  discussed 
this  question,  but  only  incidentally  to  a  subject  of  more  importance,  i.e., 
the  utilization  of  waste  heat.  Mr.  Helbig's  figures,  slightly  rearranged 
for  convenience  of  comparison,  will  be  found  in  Table  193  on  page  509. 

Results  of  actual  tests. — It  might  be  supposed  that  actual  tests  of 
the  thermal  efficiency  of  the  rotary  kiln  could  be  readily  made,,  and 
that  the  results  of  these  tests  would  afford  data  of  great  value  to  the 
manufacturer.  To  a  certain  extent  this  is  true,  but,  unfortunately,  the 
results  afforded  by  such  tests  require  interpretation,  and  this  in  turn 
requires  that  certain  chemical  constants — so  called  by  courtesy — should 
be  employed  as  bases.  These  constants  are,  for  example,  the  heat  of 
dissociation  of  the  carbonates  and  the  sulphates,  of  the  decomposition 
of  clay,  of  the  formation  of  lime  silicates  and  aluminates,  etc.  The 


506 


CEMENTS,  LIMES,  AND  PLASTERS. 


error  into  which  most  experimenters  fall  is  to  assume  that  these  con- 
stants are  quite  accurately  known.  As  a  matter  of  fact,  even  the  sim- 
plest of  them — the  heat  of  dissociation  of  lime  carbonate — is  given  a 
variation  of  almost  50  per  cent  by  different  chemists  of  about  equal 
standing;  while  the  heats  of  formation  of  the  silicates,  etc.,  are  much 
less  certain  constants.  * 

In  reporting  and  discussing  actual  tests,  or  in  reading  the  reports 
of  such  tests,  it  must,  therefore,  be  borne  in  mind  that  the  assumptions 
which  are  necessarily  made  are  based,  in  large  p#rt,  on  determinations 
of  more  than  questionable  accuracy. 

Two  such  tests  have  been  recently  published,  by  Richards  and  Car- 
penter respectively,  and  are  summarized  below. 

Richards'  tests. — Prof.  J.  W.  Richards  tested  a  60-foot  rotary  at 
the  Dexter  Portland  Cement  Company  plant,  Nazareth,  Pa.  The  cement 
mixture  and  the  resulting  clinker  are  said  to  have  had  the  following 
compositions : 


Raw  Mix. 


Clinker. 


Silica  (SiO2) 13.38  21 .27 

Alumina  (ALO.) \  A  n .  /             6 . 42 

Iron  oxide  (Fe2O3) J  1  3. 18 

Lime  (CaO) 41.96  66.70 

Magnesia  (MgO) 1 .53  2.43 

Carbon  dioxide  (CO2) 34 . 65 

Water 0.43 

The  clinker  "  analysis  "  must  evidently  have  been  calculated 
from  the  raw  mix,  and  not  obtained  by  direct  analysis. 

A  proximate  analysis  of  the  kiln  coal — bituminous  stack  from  Fair- 
mount,  W.  Va. — gave: 

Volatile  matter 38. 10 

Fixed  carbon 53 . 24 

Ash 8.06 

Moisture 0 . 60 

"The  following  ultimate  composition  of  the  coal  was  assumed  from 
average  analyses  of  coal  from  that  region  of  similar  proximate  com- 
position. 

Carbon 73 . 60 

Hydrogen 5 . 30 

Nitrogen 1 . 70 

Sulphur 0.75 

Oxygen 10 . 00 

Moisture 0 . 60 

Ash..  8.05 


HEAT  CONSUMPTION  AND   HEAT   UTILIZATION. 


507 


"The  kiln  turns  out  an  average  of  3635  Ibs.  of  clinkered  cement 
per  hour  from  5980  Ibs.  of  material  fed  to  it,  producing  200  Ibs.  of  flue- 
dust,  equal  to  3.35  per  cent  of  the  weight  of  mixture  charged.  The  coal 
used  averages  110  Ibs.  per  barrel  of  cement  produced." 

The  temperature  of  the  clinker  falling  out  of  the  lower  end  of  the 
kiln  was  measured  by  the  Le  Chatelier  pyrometer,  and  determined  to 
be  1200°  C.  =  2192°  F.  The  temperature  of  the  waste  gases,  deter- 
mined 4  feet  below  the  top  of  the  stack,  was  820°  C.  or  1508°  F.  The 
sensible  heat  in  the  clinker  (leaving  the  kiln  at  1200°  C.)  was  determined 
by  a  calorimeter  as  290  kilogram  calories  per  kilo  =  522  B.T.U.  per 
pound.  The  waste  gases  in  the  stack  analyzed  as  follows: 

Carbon  dioxide 10 . 2 

Oxygen 11.8 

Carbon  monoxide 0.2 

Sulphur  dioxide not  determined 

Water 

Nitrogen 

It  will  be  noted  that  part  of  these  preliminary  data  were  deter- 
mined by  direct  experiment,  while  others  apparently  are  "  averages/' 
or  otherwise  of  less  value  than  experimental  results.  This,  unfortu- 
nately, throws  doubt  upon  some  of  the  results  obtained,  as  noted  below. 
At  the  close  of  his  paper,  after  making  the  necessary  calculations,  Mr. 
Richards  summarized  his  results.  This  summary,  recalculated  to 
calories  and  B.T.U.  per  barrel,  is  presented  below. 

TABLE  192. 
SUMMARY  OF  RICHARDS'  TESTS  OF  ROTARY  KILNS. 

Heat-units  per  Barrel. 


Calories. 

B.T.U. 

Per  Cent. 

HEAT  SUPPLY. 
Theoretical  heating  power  of  the  fuel      

395,000 

1,567,460 

84   7 

Heat  of  combination  of  the  clinkering  materials.    .  .  . 

71,410 

283,355 

15.3 

HEAT  DISTRIBUTION. 
Heat  carried  out  by  hot  clinker 

466,410 
50025 

1,850,815 
198,499 

100.0 
10  7 

__        .                           (  in  necessary  products 

170,000 

674,560 

36  1 

Heat  in  waste  gases  |  |n  J^SS  Petc          

168,000 

666,625 

36  0 

Heat  in  the  flue-dust          

1,056 

4,190 

0.2 

Loss  bv  imperfect  combustion                             .... 

6,124 

24,300 

1  3 

Evaporation  of  water  of  charge                  

723 

2,869 

0  2 

Dissociation  of  the  carbonates            

10,814 

42,910 

2  3 

Loss  by  radiation  etc    (by  difference)       . 

59  668 

236  862 

12  8 

466,410 

1,850,815 

100.0 

508  CEMENTS,  LIMES,  AND  PLASTERS. 

In  regard  to  Richards* 'results  it  may  be  said  that  the  use  of  such 
a  large  excess  of  air  is  not  normal  practice,  either  in  the  Lehigh  district 
in  general  or  at  the  Dexter  plant  in  particular.  It  is  further  doubtful 
whether  a  kiln  run  so  wastefully  as  this  one  appears  to  have  been  could 
make  good  cement  with  a  fuel  consumption  as  low  as  110  Ibs  per  barrel. 
These  questions  throw  doubt. on  the  Calculated  loss  of  heat  in  the  waste 
gases.  The  amount  allowed  for  dissociation  of  the  carbonates  is  appar- 
ently only  about  one-tenth  of  what  should  be  allowed,  owing  to  an 
arithmetical  error.  When  this  error  is  corrected,  ^he  "loss  of  heat  by 
radiation"  is  made  a  minus  quantity.  In  Table  193  below,  this  cor- 
rection has  been  made,  but  Richards'  estimates  as  to  waste  gases  are 
left  unchanged. 

Carpenter's  tests. — Prof.  R.  C.  Carpenter  tested  two  rotary  kilns 
at  the  plant  of  the  Cayuga  Portland  Cement  Company,  near  Ithaca,  N.  Y. 
The  test  was  made  primarily  to  determine  the  efficiency,  not  of  the 
kilns,  but  of  a  boiler  designed  to  utilize  their  waste  heat. 

The  coal  used  in  the  kilns  was  Westmoreland  (Pa.)  slack  of  the 
following  composition  and  heating  value. 

Moisture , 2 . 19 

Volatile  matter 32 . 9 

Fixed  carbon 54 . 66 

Ash 10.25 

B.T.U.  per  pound 14,022 

At  the  time  of  test  the  two  kilns  were  taking  together  1889  Ibs, 
coal  per  hour,  producing  21.2  barrels  of  clinker,  equal  to  a  coal  con- 
sumption of  89.1  Ibs.  per  barrel.  This  low  fuel  consumption  is  attained 
in  part  by  the  use  of  waste  heat  from  the  clinker  as  shown  in  the  table 
below. 

Carpenter's  paper,  as  originally  published,  contained  a  number  of 
serious  typographic  errors,  which  the  author  has  kindly  corrected  on 
the  copy  sent  to  me.  In  the  table  below  I  have  therefore  made  use 
of  these  corrected  results,  so  that  the  second  column  of  this  table 
(193)  will  be  found  to  differ  considerably  from  that  given  in  the 
original. 

It  will  be  seen  that  Richards'  results,  when  corrected  for  the  carbon- 
ate requirements,  leave  no  room  for  radiation  losses. 

For  my  own  detailed  estimates  on  most  of  these  points,  the 
r  is  referred  back  to  pages  498,  501. 


HEAT  CONSUMPTION  AND  HEAT  UTILIZATION. 


50$ 


TABLE  193. 
TESTS  AND  ESTIMATES  OF  HEAT  DISTRIUBTION,  B.T.U.  PER  BBL. 


Richards. 

Carpenter. 

Helbig. 

Newberry. 

Heat  from  combustion  of  coal  
'  '     drawn  from  clinker  cooler 

1,567,460 

1,247,641 
96,273 

992,000 
149  348 

1,474,000 

"     derived  from  chemical  com- 
bination       

283,355 

132,456 

240  770 

1 

Total  heat  supplied  

1,850,815 

1,476,370 

1  382  118 

1  474  000 

Heat  used  in  evaporation  of  water  .  . 
"        •*'-."  dissociation     of     sul- 
phates   

2,869 

14,302 
11,233 

3,214 
4,500 

20,832 
11  340 

«        tt     tt  dissociation     of     car- 
bonates 

362  524 

320  253 

345  625 

344  250 

Heat  discharged  in  clinker  * 

198  499 

207  999 

165  942 

228  000 

"             "          "  stack-gases,  nec- 
essary products 

674  560 

{462  940 

Heat  discharged  in  stack-gases,  ex- 
cess air 

666  625 

700,093 

694,400 

180  000 

Heat  discharged  as  CO  (imperfect 
combustion) 

24  300 

Heat  discharged  in  flue  dust 

4  190 

14  134 

by  radiation,  etc 

222  490  f 

67  456J 

226  638§? 

Total  heat  distributed  

1,933,567 

1,476,370 

1,295,271 

1,474,000 

*  Roughly  equivalent  to  the  heat  necessary  to  bring  the  mix  up  to  the  clinkering  point. 
A  By  difference. 


By  calculation. 

Does  not  check,  owing  in  part  to  temperature  allowances. 


Heat  Utilization  and  Economics. 

Much  of  the  heat  carried  out  by  the  clinker  and  the  stack-gases  is: 
recoverable  with  some  ease,  while  that  lost  by  radiation  from  the  kiln 
is  not  so  readily  utilized.  Helbig  and  Carpenter  have  described  methods 
of  waste-heat  utilization  in  the  papers  cited  on  p.  511,  to  which  refer- 
ence should  be  made  for  further  details. 

Carpenter,  in  discussing  his  Cayuga  tests,  notes  that  "at  the  time 
of  the  test  that  portion  of  the  air  not  supplied  by  the  coal-feeding  appa- 
ratus was  forced  by  a  special  blower  through  the  hot  clinker  and  thence 
into  the  kiln.  By  this  regenerative  action  about  80  per  cent  of  the  enter- 
ing air  was  heated  to  480°  F.,  restoring  to  the  two  kilns  about  2,000,000 
B.  T.  U.  per  hour,  or  about  7  per  cent  of  the  heat  produced  by  the  com- 
bustion of  the  coal.  The  regenerator,  while  distinctly  economical,  made 
the  clinker  elevators  difficult  to  keep  in  order  and  tended  to  deliver 
dust  into  the  kiln-room;  it  also  took  up  valuable  room  and  after  a. 
few  months  of  use  was  abandoned.  The  test  shows,  however,  the: 


510  CEMENTS,  LIMES,  AND  PLASTERS. 

value  of  conserving  the  waste  heat  from  the  clinker  by  heating  the 
entering  air."  As  the  clinker  of  the  two  kilns  during  this  test  carried 
out  4,409,540  B.T.U.  per  hour,  and  the  clinker  regenerator  returned 
2,041,000  of  this,  its  efficiency  was  46.3  per  cent. 

At  a  German  Portland-cement  plant  where  the  stack-gases  are  used 
in  drying  the  raw  materials,  a  large. amount  of  very  fine  dust  settles 
from  the  stack-gases  in  the  drying  chambef.  This  dust  has  been  exam- 
ined f  by  Seger  and  Kramer,  and  found  to  consist  of  43.65  per  cent 
of  insoluble  and  56.35  per  cent  of  soluble  matter.  The  insoluble  matter 
gave:  silica  31.4  per  cent,  alumina  14.7  per  cent,  iroh  oxide  4.9  per  cent, 
lime  36.8  per  cent,  magnesia  1.3  per  cent,  loss  on  ignition  0.9  per  cent. 
The  soluble  portion  consisted  of  potassium  sulphate  61.1  per  cent,  and 
potassium  carbonate  38.9  per  cent.  Calculating  these  proportions  to 
percentages  of  the  total  dust,  we  have: 

Silica  (SiO2) 13.71 

Alumina  (A12O3) , 6.42 

Iron  oxide  (Fe2O3) 2. 14 

Lime  (CaO)   16.06 

Magnesia  (MgO) 0 . 57 

Potash  carbonate 34 . 43 

Potash  sulphate 21 . 92 

Loss  on  ignition 4 . 76 

The  composition  of  this  stack-dust  has  directed  attention  to  the 
possibility  of  utilizing  it  as  a  source  of  potash,  and  both  American 
and  foreign  patents  have  been  taken  out  to  cover  possible  processes 
for  this  purpose. 

List  of  references  on  heat  requirements. — The  following  list  con- 
tains  the  principal  papers  dealing  with  this  phase  of  cement-manufac- 
ture. Those  marked  with  an  asterisk  are  restricted  mainly  to  a  dis- 
cussion of  clinkering  temperatures,  etc. 

*  Bleininger,  A.  V.      Manufacture    of   hydraulic   cements.      Bulletin  No.  3, 

Ohio  Geological  Survey,  1904. 

*  Campbell,   E.   D.     Some   preliminary  experiments  upon  the   clinkering  of 

Portland  cement.     Journ.  Amer.  Chemical  Soc.,  vol.  24,  pp.  969-992, 
Oct.,  1902. 

*  Campbell,  E.  D.,  and  Ball,  S.     An  experiment  upon  the  influence  of  the 

fineness  of  grinding  upon  the  clinkering  of  Portland  cement.     Journ. 
Amer.  Chem.  Soc.,  vol.  25,  pp.  1103-1112,  Nov.,  1903. 

*  Campbell,  E.  D.     Further  experiments  on  the  clinkering  of  Portland  cement 

and  on  the  temperature  of  formation  of  some  of  the  constituents.    Journ. 
Amer.  Chem.  Soc.,  vol.  26,  pp.  1143-1158,  Sept.,  1904. 

f  Journ.  Soc.  Chem.  Industry,  vol.  23,  p.  661.     June  30,  1904. 


HEAT  CONSUMPTION  AND  HEAT  UTILIZATION.  511 

Carpenter,  R.  C.    A  test  of  a  process  for  utilizing  waste  heat  from  rotary 

cement-kilns.     Sibley  Journal  of  Engineering,  March,  1904. 
Helbig,  A.  B.    The  efficiency  of  waste-gas  boilers  in  connection  with  rotary 

cement-kilns.     Engineering  News,  vol.  53,  pp.  163-166,  Feb.  16,  1905. 
Newberry,  S.  B.     Fuel  consumption  in  Portland-cement  burning.     Cement 

and  Engineering  News,  July,  1901. 
Richards,  J.  W.     The  thermal  efficiency  of  a  rotary  cement-kirn.      Cement, 

vol.  5,  pp.  30-35,  1904. 


CHAPTER  XXXV. 
REQUISITES  AND  TREATMENT  OF  KILN  FUELS. 

THE  usual  fuel  in  rotary-kiln  practice  is  pulverized  bituminous  coal. 
Oil,  natural  gas,  and  producer  gas  are,  however,  used  at  several  plants, 
while  charcoal  has  recently  been  suggested  for  use  in  a  projected 
Arizona  mill.  These  fuels  will  be  discussed  in  the  order  named. 

Coal. 

Character  of  kiln  coals. — In  order  to  be  suitable  for  use  in  rotary 
kilns  the  coal  must  be  of  the  bituminous  type,  and  preferably  a  gas- 
coal.  Coals  high  in  fixed  carbon  and  low  in  volatile  matter,  while  giving 
high  temperatures,  will  not  burn  properly  when  pulverized  and  blown 
into  the  kiln,  for  they  are  slow  to  ignite.  The  anthracite  and  semi- 
bituminous  coals  are,  therefore,  ruled  out,  though  they  can  be  used 
in  small  quantities  mixed  with  gas-coal,  if  the  mixture  be  pulverized 
fine  enough. 

For  economic  reasons  the  kiln  coal  should  run  as  low  in  ash  as  pos- 
sible. The  ash  not  only  lowers  the  heating  value  of  the  coal,  but  it 
interferes  with  the  composition  of  the  mix,  for  much  of  it  is  always 
taken  up  by  the  cement  during  burning.  The  presence  of  sulphur,  in 
amounts  of  over  1J  per  cent,  is  also  technologically  a  defect,  and  if  the 
sulphur  averages  over  2  per  cent  it  is  advisable  to  look  up  a  better  coal. 

As  shown  by  the  analyses  below,  the  better  coals  actually  used 
range  in  composition  about  as  follows: 

Volatile  matter 30%-40% 

Fixed  carbon 50%-60% 

Sulphur 0%-  1|% 

Ash. 5%-  8% 

Analyses  of  kiln  coals. — The  following  table  (194)  of  analyses  of 
kiln  coals  is  fairly  representative  of  the  various  types  of  coal  actually 
in  use  in  rotary-kiln  plants. 

512 


REQUISITES  AND  TREATMENT  OF  KILN  FUELS. 


513 


TABLE  194. 
ANALYSES  OF  KILN  COALS. 


1. 

2. 

3. 

4. 

5. 

Volatile  matter     

32  90 

38  10 

31  38 

35  41 

35  26 

Fixed  carbon  

54.66 

53  24 

58  23 

56  15 

56  33 

n.  d. 

n.  d. 

n.  d. 

1  30 

1  34 

Ash           

10.25 

8.06 

9.42 

6  36 

7  06 

2.19 

0.60 

1.03 

2  08 

1  35 

6. 

7. 

8. 

9. 

10. 

Volatile  matter 

39  52 

39  37 

31  87 

37  44 

38  00 

Fixed  carbon              

51  69 

55  82 

51  05 

53  72 

51  72 

Sulphur                        .        

1  46 

0  42 

n  d 

n  d 

n  d 

Ash                     

6  13 

3  81 

5  22 

5  50 

5  38 

Moisture                             

1  40 

1  00 

11  86 

3  334 

4  90 

1.  Westmoreland,,  Pa.,  slack,  used  at  Cayuga  Cement  Co.,  Portland  Point,  N.  Y.     R.  C.  Car- 

penter.    Cement,  vol.  5,  p.  1904. 

2.  Fairmount,  W.  Va.,  slack,  used  at  Dexter  Portland  Cement  Co.,  Nazareth,  Pa.    J.  W.  Richards. 

Cement,  vol.  5,  p.  30. 

3.  Fairmount,  W.  Va.,  slack,  used  at  Alpha  Portland  Cement  Co.,  Alpha,  N.  J.     F.  E.  Walker, 

analyst. 

4.  West  Virginia  slack,  used  by  Wolverine  Portland  Cement  Co.  at  Coldwater,  Mich.     H.  E. 

Brown,  analyst.     22d  Ann.  Rep.  U.  S.  Geol.  Sur.,  pt.  3,  p.  675. 

5.  West  Virginia  slack,  used  by  Wolverine  Portland  Cement  Co.  at  Quincy,  Mich.     H.  E.  Brown, 

analyst.     22d  Ann.  Rep.  U.  S.  Geol.  Sur.,  pt.  3,  p.  675. 

6.  West  Virginia  slack,  used  by  Peninsular  Portland  Cement  Co.,  Cement  City,  Mich.     J.  G- 

Dean,  analyst.     22d  Ann.  Rep.  U.  S.  Geol.  Sur.,  pt.  3,  p.  675. 

7.  Pennsylvania  slack,  used  by  Omega  Portland  Cement  Co.,  Jonesville,  Mich.     22d  Ann.  Rep. 

U    S.  Geol.  Sur.,  pt.  3,  p.  675. 

8.  Ohio  coal,  used  by  Wellston  Portland  Cement  Co.,  Wellston,  Ohio.     W.  S.  Trueblood,  analyst. 

9.  10.     Ohio  coal,  used  by  Ironton  Portland  Cement  Co.,  Ironton,  Ohio.     C.  D.  Quick,  analyst. 


References  on  coal-fields. — The  following  reports  contain  data  on 
the  distribution  and  character  of  American  coals. 

Ashley,  G.  H.    The  coal  deposits  of  Indiana.     23d  Rep.  Indiana  Dept.  Geology 

and  Natural  Resources,  pp.  1-1573.     1899. 
Ashley,  G.  H.     The  eastern  interior  coal-field   (Illinois  and  Indiana).     22d 

Ann.  Rep.  U.  S.  Geol.  Survey,  pt.  3,  pp.  265-306.     1902. 
Bain,  H.  F.     The  western   interior   coal-field  (Iowa,  Missouri,  Kansas).     22d 

Ann.  Rep.  U.  S.  Geol.  Survey,  pt.  3,  pp.  333-366.     1902. 
Diller,  J.  S.     The  Coos  Bay  coal-field,  Oregon.     19th  Ann.  Rep.  U.  S.  Geol. 

Survey,  pt.  3,  pp.  309-376.     1898. 
Haseltine,  R.  M.     The  bituminous  coal-field  of  Ohio.     22d  Ann.  Rep.  U.  S, 

Geol.  Survey,  pt.  3,  pp.  215-226.     1902. 
Hayes,  C.  W.     The  coal-fields  of  the  United  States  (summary).      22d  Ann, 

Rep.  U.  S.  Geol.  Survey,  pt.  3,  pp.  7-24.     1902. 
Jayes,  C.  W.     The  southern  Appalachian  coal-field  (Ala.,  Ga.,  Tenn.,  Ky.,  Va.). 

22d  Ann.  Rep.  U.  S.  Geol.  Survey,  pt.  3,  pp.  227-264.     1902. 
Lane,  A.  C.     The  northern  interior  coal-field   (Michigan).      22d  Ann.  Rep. 

U.  S.  Geol.  Survey,  pt.  3,  pp.  307-332.     1902. 


514  CEMENTS,  LIMES,  AND  PLASTERS. 

Smith,  G.  0.     The  Pacific  Coast  coal-fields  (Oregon,  Washington,  California). 

22d  Ann.  Rep.  U.  S.  Geol.  Survey,  pt.  3,  pp.  473-514.     1902. 
Storrs,  L.  S.     The  Rocky  Mountain  coal-fields   (Mont.,  Wyo.,   Colo.,  Utah, 

N.  Mex.).     22d  Ann.  Rep.  U.  S.  Geol.  Survey,  pt.  3,  pp.  415-472.     1902. 
Taff,  J.  A.     The  southwestern  coal-field  (Ind.  Terr.,  Ark.,  Texas).     22d  Ann. 

Rep.  U.  S.  Geol.  Survey,  pt.  3,  pp.  367-414.     1902. 
White,  D.     The  bituminous  coal-field  dtf  Maryland.     22d  Ann.  Rep.  U.  S. 

Geol.  Survey,  pt.  3,  pp.  201-214.     1902. 
White,  D.,  and  Campbell,  M.  R.     The  bituminous  coal-field  of  Pennsylvania. 

22d  Ann.  Rep.  U.  S.  Geol.  Survey,  pt.  3,  pp.  127-^200.     1902. 
White,  J.  C.     Report  on  coal  (of  West  Virginia).     Vol.  2,  Reports  W.  Va. 

Geol.  Survey,  pp.  81-725.     1903. 
Woodworth,  J.  B.     The  Atlantic  Coast  Triassic  coal-fields   (Virginia,  North 

Carolina).     22d  Ann.  Rep.  U.  S.  Geol.  Survey,  pt.  3,  pp.  25-54.     1902. 

Crushing. — Coal  may  be  bought  in  the  shape  of  slack,  lump  or  run- 
of-mine.  In  the  former  case  no  preliminary  crushing  is  required,  for 
the  slack  can  be  readily  handled  by  ball  mills,  Griffin  mills,  or  Williams 
mills.  When  slack  is  bought,  therefore,  it  is  sent  direct  to  the  drier 
and  then  to  the  fine-reducing  mills.  But  when  lump  or  run-of-mine 
are  purchased  the  coal  can  profitably  be  crushed  before  being  sent 
to  the  drier. 


FIG.  127. — Coarse,  toothed  rolls  for  lump  coal.     (Allis-Chalmers  Co.) 

In  such  cases  the  preliminary  crushing;  seems  to  be  accomplished 
most  effectually  by  rolls.  Figs.  127  and  128  show  rolls  adapted  to  this 
kind  of  work,  both  being  made  by  the  Allis-Chalmers  Co.  The  rolls 
shown  in  Fig.  127  are  very  coarsely  toothed,  and  are  intended  for  use 
on  large  lump  or  run-of-mine  coal.  They  are  24"X30"  in  size,  and 
can  conveniently  reduce  large  lump  to  about  1-  or  2-inch  size.  In  Fig, 


REQUISITES  AND  TREATMENT  OF  KILN  FUELS.  515 

128  a  set  of  24"  X 18"  plain-faced  disintegrating  rolls  are  shown.  These 
will  handle  coal  up  to  say,  4  to  6  inch  size,  and  reduce  it  economically 
to  |  or  J  inch.  Finer  than  this  it  is  hardly  profitable  to  go,  for  J-incn 
coal  is  readily  dried  and  is  of  convenient  size  for  either  ball,  Griffin, 
or  Williams  mills. 

Drying  coal. — Coal,  as  bought,  may  carry  as  high  as  15  per  cent 
of  water  in  winter  or  wet  seasons;  usually,  it  will  run  from  3  to  8  per 
cent.  To  secure  good  results  from  the  crushing  machinery  it  is  neces- 
sary that  this  water  should  be  driven  off.  For  coal  drying,  as  for 
the  drying  of  raw  materials,  the  rotary  drier  seems  best  adapted  to 


FIG.  128. — Rolls  for  coal-crushing.     (Allis-Chalmers  Co.) 

American  conditions.  Several  types  of  these  driers  are  discussed  on 
pp.  400  and  649.  It  should  be  said,  however,  that  in  drying  coal  it  is 
inadvisable  to  allow  the  products  of  combustion  to  pass  through 
the  cylinder  in  which  the  coal  is  being  dried.  This  restriction  serves 
to  decrease  slightly  the  possible  economy  of  the  drier,  but  an  evap- 
oration of  6  to  8  pounds  of  water  per  pound  of  fuel  coal  can  still 
be  counted  "on  with  any  good  drier.  The  fuel  cost  of  drying  coal 
containing  8  per  cent  of  moisture,  allowing  $2  per  ton  for  the  coal 
used  as  fuel,  will  therefore  be  about  3  to  4  cents  per  ton  of  dried  product. 
Pulverizing  coal. — Though  apparently  brittle  enough  when  in  large 
lumps,  coal  is  a  difficult  material  to  pulverize  finely.  For  cement-kiln 
use,  the  fineness  of  reduction  is  very  variable.  The  finer  the  coal  is 
pulverized  the  better  results  will  be  obtained  from  it  in  the  kiln,  and 
the  poorer  the  quality  of  the  coal  the  finer  it  is  necessary  to  pulverize 
it.  The  fineness  attained  in  practice  may,  therefore,  vary  from  85  per 
cent  through  a  100-mesh  sieve  to  95  per  cent  or  more  through  the 
same.  At  one  plant  a  very  poor  but  cheap  coal  is  pulverized  to  pass 
98  per  cent  through  a  100-mesh  sieve,  and  in  consequence  gives  very 
good  results  in  the  kiln. 


515  CEMENTS,  LIMES,  AND  PLASTERS. 

Coal-pulverizing  is  usually  carried  on  in  two  stages,  the  material 
being  first  crushed  to  20-  or  30-mesh  in  a  Williams  mill  or  ball  mill  and 
finally  reduced  in  a  tube  mill.  At  many  plants,  however,  the  entire 
reduction  takes  place  in  one  stage,  Griffin  or  Huntingdon  mills  being 
used. 

Descriptions  of  the  WiHiams,  Grjtffin,  and  Huntingdon  mills,  and 
of  several  makes  of  ball  mills  and  tube  mills,  will  be  found  in  Chapter 
XXXV.  The  Smidth  ball  mill,  however,  was  not  described  in  that 
chapter,  and  as  it  is  recommended  by  its  manufacturers  for  use  as  an  inter- 
mediate reducer  on  coal,  its  general  make-up  can  properly  be  noted  here. 

The  following  description  of  the  Smidth  ball  mill  is  given  sby  its 
makers : 

"The  illustration  (Fig.  129)  shows  the  internal  arrangement  of  the 
type  A  ball  mill.  This  machine  has  a  through-shaft,  with  journals 
running  in  bearings  at  both  ends. 

"The  machine  consists  of  a  drum  with  two  strong  end-plates  c, 
between  which  the  curved  drum-plates  d  are  fixed.  As  will  be  seen 
these  drum-plates  do  not  form  a  cylinder,  but  one  end  of  each  is  set 
a  few  inches  toward  the  center,  forming  steps.  The  balls  and  materials 
tumble  over  these  steps  when  the  drum  revolves,  and  by  this  the  pound- 
ing action  of  the  balls  is  considerably  increased,  the  steps  at  the  same 
time  allowing  the  residue  from  the  sieve  to  be  caught  and  re-enter  the 
drum.  The  curved  drum-plates  are  protected  on  the  inside  by  thick 
steel  plates  e  which  are  divided  in  several  sections,  so  that  each  sec- 
tion can  be  separately  renewed.  The  lining  plates  are  fixed  by  means 
of  bolts.  The  end-plates  c  are  also  lined  with  thick  plates  d. 

"The  grinding-plates  have  rows  of  perforations  /  through  which 
the  crushed  material  constantly  falls  on  the  slotted-steel  screen-plates 
g.  Whatever  is  fine  enough  to  pass  these  screen-plates  falls  on  the 
inner  sieves  I,  which  are  coarse  and  strong  sieves,  and  that  which 
passes  through  these  falls  on  the  finishing-sieves  k.  The  material 
passing  the  finishing-sieves  is  collected  in  the  lower  hopper-shaped  part 
of  the  dust-casing  m  surrounding  the  drum,  and  from  this  it  either 
falls  to  a  conveyor  or  elevator,  or  may  be  dropped  direct  into  the  con- 
tainers. The  outlet  of  the  dust-casing  is  provided  with  a  slide-gate. 

"The  residue  from  the  sieves,  coarse  and  fine,  is  carried- up  with  the 
mill  until  it  falls  through  large  holes  in  the  curved  part  /  of  the  slotted- 
steel  screen-plates,  and,  together  with  the  residue  from  the  slotted-steel 
screen-plates  themselves,  falls  into  the  drum  again  through  the  steps. 

"In  one  of  the  end-plates  a  manhole  is  fitted  and  in  the  dust-cas- 
ing a  door  corresponding  to  the  manhole,  giving  access  to  the  interior 


REQUISITES   AND  TREATMENT  OF  KILN   FUELS. 


517 


518  CEMENTS,  LIMES,  AND  PLASTERS. 

of  the  mill.  The  dust-casing  is  made  in  three  parts ,  a  small  section 
being  easily  removable  for  brushing  the  sieves.  The  top  half  may  be 
removed  for  repair  of  the  drum. 

"The  illustration  below  (Fig.  130)  shows  the  type  B  machine,  which 
is  the  same  as  type  A;  except  that  the  shaft,  instead  of  going  through 
the  feed-hopper,  is  stopped  short  inside  the  drum  and  there  fixed  in  a 
' spider'  the  external  part  of  which  runs  on  a  roller  bearing.  By  means 
of  this  arrangement  lumps  up  to  10  inches  each  way  can  be  fed  into  the 
mill,  and  the  feed  opening  itself  at  the  same  time  is  reduced  in  diameter, 
which  allows  a  heavier  charge  of  balls  to  be  used. 

"The  very  large  capacity  of  the  Davidsen  tube  mill  as  a  pul- 
verizer created  the  demand  for  a  large  ball  mill  of  sufficient  capacity 
to  feed  the  tube  mill  with  coarse  material.  This  demand  has  been 
met  by  the  type  C  ball  mill,  in  the  construction  of  which  the  through- 
shaft  of  type  A  and  the  'spider''  of  type  B  have  been  omitted,  giving 
a  clear  feeding  opening  of  10  inches  without  interference.  The  omis- 
sion of  the  shaft  and  the  'spider'  have  made  it  possible  to  use  a  much 
larger  charge  of  steel  balls  and  at  the  same  time  lower  the  cost  of  repairs 
by  avoiding  the  necessity  for  replacement  of  either  shaft  or  'spider'. 


FIG.   130. — Smidth  ball  mill.     (F.  L.  Smidth&  Co.)     Type  B,  showing  roller  bearing 

as  used  on  type  C. 

"  Up  to  this  time  there  has  been  but  one  size  of  the  type  C  constructed, 
namely,  No.  7.  This  has  become  the  popular  form  and  size  for  Port- 
land-cement work.  One  No.  7  ball  mill  and  one  No.  12  tube  mill  can 
be  brought  together  as  a  grinding  unit  through  placing  on  the  ball-mill 


REQUISITES  AND  TREATMENT  OF  KILN  FUELS.  519 

screen-frames  wire  cloth  of  such  mesh  as  shall  be  shown  by  the  grinda- 
bility  of  the  material  to  pass  the  proper  capacity  for  pulverization  in 
the  tube  mill.  No.  7  ball  mill  requires  at  the  maximum  18  horse-power 
and  uses  a  floor  space  of  11  feet  4  inches  by  15  feet  7  inches.  Like  the 
tube  mill,  the  ball  mill  is  a  slow-speed  machine,  making  22  revolutions 
per  minute. 

"The  parts  most  subjected  to  wear  are  the  grinding-plates,  the  side 
linings,  the  gear,  and  the  pinion.  Depending  entirely  upon  the  char- 
acter of  the  material,  the  grinding-plates  should  give  a  wear  of  from 
six  to  eighteen  months.  The  side  linings  do  not  wear  so  rapidly.  As 
the  gear  and  pinion  are  operated  at  slow  speed  the  wear  on  these  is 
relatively  small.  Gears  are  seldom  replaced  short  of  one  or  two  years 
and  pinions  have  a  life  of  from  six  to  twelve  months.  Of  course  gears 
and  pinions  wear  in  proportion  to  the  attention  given  to  lubrication 
and  protection  from  dust." 

Power  and  output  in  coal-grinding. — There  is  probably  greater 
diversity  in  coal-grinding  practice  than  in  the  grinding  of  either  raw 
material  or  clinker.  Grinding-machines  of  many  different  types  are 
in  use;  the  coal  reaches  the  plant  in  various  sizes  from  slack  to  lump, 
and  is  ground  to  different  finenesses.  All  this  makes  it  difficult  to  esti- 
mate closely  on  the  power  requirements  and  output  of  the  coal-grind- 
ing mill,  but  the  following  data  may  be  of  use  in  this  connection. 

A  Williams  mill  employed  at  an  Illinois  cement-plant,  working  on 
Illinois  coal  from  the  dryer  and  preparing  it  for  the  tube  mills,  ground 
six  tons  of  coal  per  hour  to  the  following  fineness. 

Mesh  of  sieve 20  50  100  200 

Per  cent  residue 6.9         43 . 3         76 . 2         87 . 3 

Per  cent  passing. 93.1         56.7         23.8         12.7 

If  the  results  of  this  test  be  compared  with  those  given  on  p.  — 
for  the  same  mill  ..working  on  raw  materials,  it  will  be  seen  that  coal 
is  very  readily  crushed  to  20-mesh,  and  quite  easily  to  50-mesh.  But 
the  percentages  of  coal  passing  the  100-mesh  and  200-mesh  sieves 
respectively  are  very  much  lower  than  the  percentages  of  raw  mix 
passing  the  same  sieves. 

A  Griffin  mill  grinding  coal  from  rolls  or  small  crushers  will  reduce 
about  two  tons  per  hour  to  a  fineness  of  95  per  cent  through  a  100- 
mesh  screen,  taking  25  to  30  H.P.  in  doing  so. 

Slack  coal  for  three  kilns  is  ground  at  one  plant  in  a  single  No.  16 
Davidsen  tube  mill,  the  product  being  about  three  tons  per  hour. 

The  above  data  show  a  considerable  variation  in  the  power  required 


520  CEMENTS,  LIMES,  AND  PLASTERS. 

for  coal-grinding,  the  performances  quoted  being  equivalent  to  power 
consumptions  of  from  5  to  15  H.P.  hours  per  ton  of  coal  ground.  Mr. 
C.  D.  Bartlett,  in  discussing  *  this  question,  states  that  a  good  mill  will 
handle  slack  at  the  rate  of  four  tons  per  hour,  crushing  it  to  80-mesh 
and  using  about  25  H.P.  in  doing  so.  For  kiln  use,  of  course,  the  fine- 
ness must  be  considerably  greater  than  this. 

Total  cost  of  coal  preparation. — *The  total  cost  of  crushing  (if  neces- 
sary), drying,  and  pulverizing  coal,  and  of  conveying  and  feeding  the 
product  to  the  kiln,  together  with  fair  allowances  ^or  replacements  and 
repairs,  and  for  interest  on  the  plant,  will  probably  range  from  about  20 
to  30  cents  per  ton  of  dried  coal  for  a  four-kiln  plant.  This  will  be 
equivalent  to  a  cost  of  from  3  to  5  cents  per  barrel  of  cement.  While 
this  may  seem  a  heavy  addition  to  the  cost  of  cement-manufacture,  it 
should  be  remembered  that  careful  drying  and  fine  pulverizing  enable 
the  manufacturer  to  use  much  poorer,  and  therefore  cheaper,  grades  of 
coal  than  could  otherwise  be  utilized. 

The  coal  used  at  American  plants  costs  from  80  cents  to  $2.50  per 
ton  delivered  at  the  mill,  according  to  the  quality  of  the  coal  and  the 
location  of  the  mill.  In  the  West,  where  good  coal  is  far  more  expensive 
than  stated,  oil  is  used  in  its  place. 

It  is  probably  safe  to  say  that  if  a  plant  is  so  located  that  coal  will 
cost  over  $4  per  ton,  and  no  oil  or  gas  is  obtainable,  the  rotary 
kiln  is  too  expensive  for  use.  Under  such  fuel  conditions  it  is  probably 
best  to  install  stationary  kilns  of  one  of  the  improved  designs  described 
in  Chapter  XXXII.  This  is  particularly  the  case  if  a  wet  mix  be  used 
in  the  kilns. 

Fire  and  explosion  risks. — The  coal-handling  end  of  the  plant  is 
subject  to  two  quite  distinct,  though  related,  kinds  of  risks — from 
explosion  and  fire  respectively.  Precautions  must  be  taken  to  guard 
.against  both  of  these  dangers. 

Explosions  may  occur  when  finely  divided  powdered  coal  is  given 
free  access  to  air.  In  order  to  keep  as  little  powdered  coal  on  hand  as 
possible,  the  coal-mill  is  usually  run  so  as  to  just  supply  the  kilns.  This 
has  some  inconveniences,  but  it  lessens  the  risk.  During  grinding 
care  must  be  taken  to  prevent  the  use  of  exposed  lights  or  even  motors, 
which  are  apt  to  spark,  in  the  coal-pulverizing  building.  The  methods 
of  supplying  coal  to  the  kiln  should  give  as  little  access  to  air  as  possible. 
Separation  by  blowing  is,  of  course,  inadmissible,  as  was  emphasized 
by  the  fatal  results  at  the  Edison  plant  in  1903. 

*  Journ.  Assoc.  Engineering  Societies,  vol.  31,  pp.  44-48.     1903. 


REQUISITES  AND  TREATMENT  OF   KILN   FUELS.  521 

In  addition  to  the  risk  of  explosion  from  coal-dust,  there  is  always 
the  chance  that  coal  stored  in  bulk  will  heat  up  and  cause  a  disastrous 
fire. 

The  following  statement  regarding  coal  storage  has  been  recently 
published  *  by  F.  M.  Griswold,  General  Inspector  to  the  Home  Insurance 
Company,  of  New  York: 

"The  quantity  stored  in  any  one  pile,  heap,  pocket,  or  bunker  should 
in  no  case  exceed  1,500  tons.  When  a  greater  quantity  must  be  stored 
there  should  be  a  clear  space  of  at  least  5  feet  between  the  piles,  and  that 
space  should  be  maintained  absolutely  free  for  ventilation  and  disper- 
sion of  gases  from  the  mass. 

"No  accumulation  of  coal  of  1500  tons  or  less  should  be  piled  in 
excess  of  12  feet  in  height,  when  trimmed  off,  or  squared,  but  where 
such  accumulation  is  delivered  from  dump-cars  on  a  trestle  over  12 
feet  in  height,  the  extreme  height  of  the  pile  formed  by  the  natural  run 
of  the  coal  as  dumped  may  be  15  feet,  but  not  more. 

"Where  coal  is  stored  under  shelter,  there  should  be  perfect  ventila- 
tion, to  facilitate  escape  of  gas  by  circulation  of  the  atmosphere. 

"Wet  coal,  especially  that  wetted  by  snow  and  ice,  should  be  dis- 
posed for  immediate  use;  if  its  storage  be  necessary,  it  should  be  placed 
at  the  top  of  the  pile  and  be  spread  out  as  thinly  as  practicable,  in  order 
to  expedite  drying. 

"All  accumulations  of  coal,  large  or  small,  should  be  'rod-tested' 
with  frequency  and  regularity,  in  order  to  discover  any  tendency  toward 
dangerous  heating,  the  danger-point  being  set  at  about  160°  F.  If  that 
terrfperature  be  reached,  the  exact  locality  of  increasing  heat  may  be 
determined  by  inserting  an  iron  pipe,  into  which  a  self-registering  ther- 
mometer can  be  lowered,  allowing  it  to  remain  for  sufficient  time  to 
record  the  full  intensity  of  the  heating." 

List  of  references  on  coal  drying,  grinding,  etc. 

Bartlett,  C.  D.     The  burning  of  pulverized  coal.     Journ.  Assoc.  Engineering 

*  Societies,  vol.  Cl,  pp.  44-48.     1903. 
Doane,  A.  0.    The  spontaneous  ignition  of  coal.     Engineering  News,  vol.  52, 

p.  141.    Aug.  18,  1904. 
Frazier,  W.  H.      Fire  hazards  in  Portland-cement  mills.     New  York  Journal 

of  Commerce,  April,  1901. 
Griswold,  F.  M.    Specifications  for  storage  of  bituminous  coal.     Engineering 

and  Mining  Journal,  vol.  77,  p.  725.     1904.     Engineering  News,  vol.  52, 

pp.  409-410.     Nov.  10,  1904. 

*  Engineering  and  Mining  Journal,  vol.  77,  p.  725.     1904. 


522  CEMENTS,  LIMES,  AND  PLASTERS. 

Lathbury,  B.  B.,  and  Spackman,  H.  S.  The  Lathbury  and  Spackman  coal- 
drier.  The  Rotary  Kiln,  pp.  150-151.  1902. 

Anon.  Powdered  fuel  for  boiler-furnaces  at  the  Alpha  Cement  Co.'s  works, 
Alpha,  N.  J.  Engineering  News,  1897. 

Anon.  A  new  system  for  burning  powdered  coal.  Engineering  News,  vol.  48, 
p.  548.  Dec.  25,  1902.  , 

Oil. 

Petroleum  was  early  used  in  New  York  and  Pennsylvania  as  a  fuel 
for  rotary  kilns,  but  was  gradually  supplanted  by  powdered  coal.  At 
present  no  Eastern  plants  use  oil  as  fuel.  In  the  West,  however,  where 
good  gas  coals  are  unobtainable  at  reasonable  prices,  oil  is  now  in  use 
at  four  Portland-cement  plants. 

From  11  to  14  gallons  of  oil  are  required  in  Western  practice  to 
burn  a  barrel  of  cement ;  a  safe  estimate  is  that  one  barrel  of  oil  (42  gal- 
lons) will  burn  three  barrels  of  cement.  Oil  may,  therefore,  be  com- 
pared with  coal,  in  the  rotary  kiln,  on  the  basis  of  1  gallon  of  oil  being 
equal  in  effect  to  10  Ibs.  of  coal. 

List  of  references  on  petroleum. — The  papers  on  petroleum  contained 
in  the  following  list  are  of  interest  either  as  containing  discussions  of  the 
fuel  value  of  petroleum,  or  as  describing  certain  oil  fields  whose  product 
is  at  present  utilized  in  Portland-cement  manufacture. 

Eldridge,  G.  H.  The  Florence  oil  field,  Colorado.  Trans.  Amer.  Inst.  Mining 
Engrs.,  vol.  20,  pp.  442-462.  1892. 

Eldridge,  G.  H.  The  petroleum  fields  of  California.  Bulletin  213,  U.  S. 
Geological  Survey,  pp.  306-321.  1903. 

Fenneman,  N.  M.  The  Boulder,  Colorado,  oil  field.  Bulletin  213,  U.  S.  Geolog- 
ical Survey,  pp.  322-332.  1903. 

Peckham,  S.  F.  Petroleum  in  southern  California.  Science,  vol.  23,  pp.  74- 
75.  1894. 

Anon.  Fuel  oil  on  the  Pacific  Coast.  Engineering  and  Mining  Journal, 
Dec.  20,  1902. 

Natural  Gas. 

Use  of  natural  gas  in  kilns. — Natural  gas  is  at  present  used  as  a 
kiln  fuel  in  several  Kansas  plants  and  at  one  in  Ohio.  As  a  kiln  fuel 
it  is  satisfactory  enough,  giving  as  much  results  per  B.T.U.  as  does 
a  good  coal.  Apparently,  however,  a  gas-fired  kiln  cannot  be  pushed 
as  hard  as  a  kiln  using  coal,  though  the  data  are  insufficient  to  give 
any  decisive  evidence  on  this  point.  A  recent  report  on  a  Western 
cement  proposition  states  that  the  natural  gas  to  be  used  in  the  kilns 


REQUISITES  AND  TREATMENT  OF  KILN  FUELS. 


523 


has  been  contracted  for  at  the  rate  of  3  cents  per  thousand  feet.     This 
is  about  equivalent  to  coal  at  90  cents  per  ton. 

Analyses  and  thermal  value. — The  following  analyses,  made  *  by 
Prof.  E.  H.  S.  Bailey,  will  serve  to  give  some  idea  of  the  composition 
of  natural  gas  from  a  number  of  Kansas  localities. 

TABLE  195. 
ANALYSES  OF  NATURAL  GAS,  KANSAS. 


lola. 

Inde- 
pend- 
ence. 

Cherry- 
vale. 

Coffey- 
ville. 

Paola. 

Ossawat- 
omie. 

Hydrogen  (H)      

0  00 

0.00 

0.00 

0.00 

0  00 

0  00 

Oxvgen  (O)     

0  45 

trace 

0.22 

0.12 

0  45 

trace 

Nitrogen  (N)     

7.76 

3.28 

5.94 

2.21 

2  34 

0  60 

Carbon  monoxide  (CO)  

1.23 

0.33 

1.16 

0.91 

1.57 

1  33 

Carbon  dioxide  (CO2) 

0  90 

0  44 

0  22 

0  00 

0  33 

0  22 

Ethvlene  series  (C2H4,  etc.)  

0.00 

0.67 

0.00 

0.35 

0.11 

0  22 

Marsh-gas  (CH4)  

89  .  66 

95.28 

92.46 

96.41 

95.20 

97.63 

TABLE  196. 
THERMAL  VALUES  OF  NATURAL  GAS. 


State. 

Field. 

B.T.U. 

per 
Cubic 
Foot. 

State. 

Field. 

B.T.U. 

per 
Cubic 
Foot. 

Indiana 

Anderson    

1021 

Pennsylvania 

East  Liberty 

592 

«  i 

Kokomo  

1030 

Grapeville 

823 

«  < 

Marion      

1024 

(i 

« 

891 

(  ( 

Muncie    

1019 

(( 

Harvey         .    . 

990 

Kentucky  .  . 

Louisville  

939 

n 

Leechburg 

1073 

New  York    .  .  . 

Olean  

1071 

t  ( 

St   Joe 

1170 

<  i        (i 

West  Bloomfield 

998 

West  Virginia 

Fairmount  

1137 

Ohio 

Findlay         ...    . 

1100 

(i            it 

Lurnberport  .  .  . 

1131 

1  1 

i  ( 

1020 

K            (t 

Morgantown  .  .  . 

1143 

1  1 

Fostoria      

1016 

ti            n 

Shinnston  

1141 

1  t 

St-  Mary's 

1028 

n            fi 

1  1 

1144 

Pennsylvania 

Cherrv  Tree 

840 

«            tt 

n 

1065 

Creighton  

1025 

List  of  references  on  natural  gas. — Of  the  following  papers,  those 
marked  with  an  asterisk  are  of  interest  as  discussions  of  the  fuel  value 
of  natural  gas,  while  those  unmarked  contain  data  on  its  utilization 
in  the  lola  district. 

Adams,  G.  I.,  and  others.     Economic  geology  of  the  lola  quadrangle,  Kansas. 
Bulletin  238,  U.  S.  Geological  Survey,  83  pp.     1904. 

*  "Mineral  Resources  of  Kansas  for  1897  ",  p.  52. 


524  CEMENTS,  LIMES,  AND  PLASTERS. 

Crane,  W.   R.     Natural  gas  in  steam  production   (in  Kansas).    Mines  and 

Minerals,  vol.  24,  pp.  154-156.     Nov.,  1903. 
Grimsley,  G.  P.     A  new  Portland- cement  mill  in  the  gas-fields  of  Kansas. 

Engineering  and  Mining  Journal,  Feb.  16,  1901. 
Bailey,  E.  H.  S.     Natural  gas  and  coal  oil  in  Kansas.     Kansas  University 

Quarterly,  vol.  4,  pp.  1-1 4.     1895. 

*  Bownocker,  J.  A.     Occurrence  and  exploitation  of  petroleum  and  natural 

gas  in  Ohio.     Bulletin  1,  4th  Series,  Ohio  Geol.  Survey,  1903,  p.  125. 

*  Ford,  S.  A.     Fuel  value  of  Pittsburg  gas.     American  Manufacturer,  supple- 

ment, April,  1886.  , 

*  Howard,  C.  D.     Composition  and  fuel  value  of  West  Virginia  gas.     Vol.  la, 

Reports  West  Virginia  Geol.  Survey,  pp.  553-556.     1904. 

*  Orton,  E.     Preliminary  Report  upon  Petroleum  and  Natural  Gas  (in  Ohio). 

1887,  pp.  53-54. 

*  Phillips,  F.  C.     The  chemical  composition  of  natural  gas.     Report  I,  2d 

Geol.  Survey  Penna.,  pp.  787-827.     1887. 

*  Phillips,  F.  C.     The  chemical  composition  of  natural  gas.     Vol.  la,  Reports 

Wes^  Virginia  Geological  Survey,  1904,  pp.  513-552. 

*  White,   I.   C.     The   composition  of  natural  gas.      Vol.   la,   Reports  West 

Virginia  Geological  Survey,  1904,^  pp.  513-557. 

Producer-gas. 

Producer-gas  has  been  used  in  rotary  kilns  at  three  American  plants 
at  least.  Two  of  these  plants  report  that  their  best  fuel  consumption, 
when  producer-gas  was  used,  was  equivalent  to  220  to  240  Ibs.  coal 
per  barrel  of  cement.  The  third  plant,  however,  has  recently  experi- 
mented with  the  Swindell  gas-producer,  and  reports  that  a  really  eco- 
nomical fuel  consumption  is  attained. 

Producer-gas  from  wood  or  lignite. — A  cement-plant  located  in  a 
district  where  wood,  lignite,  or  poor  coal  were  the  only  natural  fuels 
would  probably  get  good  results  by  utilizing  these  fuels  in  the  gas-pro- 
ducer. A  recent  installation  of  this  type  at  a  Mexican  copper-plant 
has  utilized  wood,  bituminous  coal,  and  anthracite. 

This  plant,  in  respect  to  the  use  of  wood,  is  described  t  as  follows : 

"The  plant  has  been  operated  with  wood  and  with  coal,  both  anthra- 
cite and  bituminous.  The  down-draught  principle  of  the  producers,  by 
which  all  gases  pass  out  through  the  bottom  of  the  fire,  has  proved 
thoroughly  efficacious  in  producing  fixed  gases  from  all  kinds  of  fuel 
used  at  Nacozari.  The  water  from  the  scrubber  rarely  shows  even 
that  trace  of  tar  which  manifests  itself  by  an  iridescent  film  on  the  sur- 
face of  the  water  in  the  lower  scrubber  tank. 

f  Langton,  J.  The  power-plant  of  the  Moctezuma  Copper  Co.,  Mexico.  Trans. 
Amer  Inst.  Mining  Engineers,  Oct.,  1903. 


REQUISITES  AND  TREATMENT  OF  KILN    FUELS. 


525 


"  The  use  of  producer-gas  made  from  wood  alone  is  the  most  novel 
feature  of  the  plant.  No  guiding  experience  was  found  for  this  process; 
but,  with  the  desire  to  utilize  as  far  as  possible  the  limited  local  wood- 
supply,  the  gas-producer  plant  was  selected  with  the  object,  among 
other  things,  of  determining  the  advisability  of  using,  if  not  wood  alone, 
at  least  a  considerable  admixture  of  wood  with  bituminous  coal.  The 
most  obivous  difficulty  to  be  feared  arose  from  the  large  proportion 
of  condensible  distillates  yielded  by  wood,  and  the  danger  that  some 
portion  of  these  might  be  imperfectly  fixed  in  passing  through  the  pro- 
ducer. The  trouble  from  tar  deposited  in  the  gas  apparatus  and  pipes 
would  be  serious,  and  even  a  small  quantity  of  tar  in  the  gas  itself  is. 
a  fertile  source  of  trouble  at  the  engine-valves.  Unless  a  permanent 
gas  could  be  made  from  wood,  this  fuel  would  be  unavailable. 

"  The  first  care,  therefore,  was  to  insure  that  there  should  be  a  bed 
of  charcoal  on  the  grate  sufficient  to  form  an  adequate  fixing-zone.  To 
obtain  this  the  producers  were  filled  about  5  feet  deep  with  cordwood 
sawn  in  blocks  about  6  inches  long  and  the  contents  blown  with  a  slow 
fire  for  four  or  five  hours  before  the  gas  was  turned  into  the  holder. 
The  gas,  as  it  proved,  was  turned  into  the  holder  too  soon.  At  first 
it  contained  some  tar,  and  it  was  not  until  after  three  hours'  operation 
that  the  charcoal  accumulated  in  sufficient  quantity,  so  that  the  pro- 
ducers delivered  fixed  permanent  gases  to  the  holder. 

"The  character  of  the  gas  produced  from  different  fuels  is  shown 
by  the  following  averages  from  a  series  of  analyses  made  by  A.  Sand- 
berg,  of  Lund,  during  the  final  trials  of  the  gas-making  plant,  which 
extended  from  February  16  to  March  20,  1901. 

AVERAGE  COMPOSITION  OF  GAS  FROM  DIFFERENT  FUELS. 


Fuel. 

Components. 

CO. 

H. 

CH4. 

CuH2N. 

CO2. 

Anthracite  coal 

21.6 
20.32 
13.27 

12.68 
13.08 
20.97 

1.86 
2.35 
2.61 

0.18 

0.2 

0.28 

8.1 
7.66 
15.96 

Bituminous  coal 

Wood 

Fuel. 

Components. 

Calorific  Value. 
B.T.U.  per  Cubic  Foot  at60°F. 
and  29.9  Inches  Barometric 
Pressure. 

O. 

N. 

Anthracite  coal 

0.2 
0.04 
0.11 

55.38 
55.35 
46.80 

131.1 

133.27 
140.22 

Bituminous  coal 

Wood                       

526  CEMENTS,  LIMES,  AND  PLASTERS. 

"As  compared  with  coal-gas,  the  proportions  of  CO  and  H  in  wood- 
gas  are  reversed,  and  the  percentage  of  CC>2  is  doubled.  With  the 
typical  compositions  (see  page  525)  the  wood-gas  shows  less  tendency 
than  the  coal-gas  to  pre-ignition  in  the  engines.  This  effect  appears  to 
be  due  to  the  large  proportion  of  CO2,  but  the  reason  why  this  is  so 
is  not  apparent."  ^ 

Charcoal. 

The  use  of  charcoal  as  a  rotary  kiln  fuel  has  been  seriously  sug- 
gested recently  by  at  least  one  engineer  for  a  plant  located  where  no 
other  type  of  fuel  was  obtainable  at  reasonable  rates.  It  is,  however, 
a  matter  of  serious  doubt  whether  this  material  could  be  brought  to 
ignite  properly  before  it  reached  the  stack. 


CHAPTER  XXXVI. 
CLINKER  COOLING,  GRINDING,  AND  STORAGE.    USE  OF  GYPSUM. 

THE  clinker,  issuing  hot  from  the  rotary  kilns,  must  be  very  finely 
ground  in  order  to  convert  it  into  cement.  This  involves  cooling  the 
clinker  previous  to  grinding;  otherwise  the  hot  clinker  would  be 
difficult  to  handle  both  in  transportation  and  in  the  pulverizing  ma- 
chinery. A  third  requisite  of  the  process  is  that  either  the  clinker  or 
the  ground  cement  must  be  seasoned,  in  some  way,  in  order  to  slake 
any  free  lime  that  may  be  present.  Modern  clinker  invariably  contains 
some  free  lime,  and  while  its  effects  may  be  masked  by  the  free  use  of 
gypsum,  it  is  advisable  to  give  it  as  much  opportunity  as  possible  to 
slake  and  become  inert. 

In  the  present  chapter,  therefore,  the  subjects  of  clinker-cooling, 
clinker-grinding,  the  use  of  gypsum  and  cement  storage  will  be  taken 
up. 

Clinker-cooling. 

General  methods  of  clinker-cooling. — Methods  of  clinker-cooling  vary 
exceedingly  in  their  processes  and  effectiveness.  At  one  extreme  might 
be  placed  the  device,  used  at  one  plant  only,  of  receiving  the  clinker 
from  each  kiln  in  a  shute  which  passes  through  the  wall  of  the  kiln  build- 
ing and  deposits  the  clinker  in  a  heap  on  the  ground  outside.  This  is, 
of  course,  a  remarkably  simple  process,  mechanically,  but  as  it  involves 
hand-labor  to  an  alarming  extent  it  is  hardly  probable  that  any  other 
American  plants  will  take  it  up.  At  the  other  extreme  is,  decidedly, 
the  Atlas  two-stage  cooling  system. 

Omitting  the  crude  device  first  mentio'ned  above,  clinker-cooling 
systems  may  be  roughly  grouped  as  follows: 

(1)  Pan  conveyors,  rolls,  and  sprinkling. 

(2)  Stationary  tower  coolers. 

(3)  One-stage  rotary  coolers. 

(4)  Two-stage  (Atlas)  rotary  coolers. 

These  methods  will  be  briefly  discussed  in  the  order  named. 

527 


528 


CEMENTS,  LIMES,  AND   PLASTERS. 


Pan  conveyors,  rolls,  and  sprinkling. — At  a  number  of  plants  the 
hot  clinker  is  caught,  as  it  drops  out  of  the  kiln,  in  pan  conveyors.  As 
it  passes  along  in  these  it  is  sprinkled  with  fine  jets  of  water,  and  at 
some  point  of  its  progress  is  passed  through  a  pair  of  rolls.  This  method 
therefore,  contains  all  the  elements  of  any  cooling  system,  and  in  a 
very  simple  form.  It  is  not  adapted  to  utilize  the  heat  of  the  clinker 
however,  and  the  product  even  after  ^sprinkling  and  passing  the  rolls 
is  too  hot  to  be  sent  immediately  to  the  grinding-mills.  The  simplicity 
of  the  method  is  therefore  counterbalanced  by  a  loss  of  heat  and  rela- 
tively high  amuont  of  hand-labor. 

Stationary  tower  coolers. — Many  plants  use  stationary  coolers  in 
the  form  of  towers.  The  Mosser  cooler,  shown  in  section  in  Fig.  131, 
is  a  good  example  of  this  type.  The  cooling  installation  at  the  Buck- 
horn  plant  is  described  as  follows  by  Mr.  Humphreys  in  Engineering 
News :  * 


FIG.  131. — Tower  cooler,  Buckhorn  Portland  Cement  Co.     (Engineering  News.) 

"Each  pair  of  kilns  discharges  through  a  fire-brick-lined  shute  into 
the  boot  of  a  single-chain  open  elevator. 

"As  the  clinker  falls  into  the  buckets  of  this  elevator  it  is  sprayed 

*  Humphreys,  R.L.     The  plant  of  the  Buckhorn  Portland  Cement  Co.     Engi- 
neering News,  vol.  50,  pp.  408-411.     Nov.  5,  1903. 


CLINKER  COOLING,  GRINDING,  AND  STORAGE.  529 

with  water.  The  elevator  dumps  the  clinker  into  a  cooler  built  by  Wm. 
F.  Mosser  &  Son.  There  are  three  of  these  coolers,  each  32  feet  high, 
8  feet  in  diameter,  having  a  cast-iron  blast-pipe  running  through  the 
center,  with  sheet-steel  conical  shields  every  5  feet,  extending  to  within 
10  inches  of  the  shell  of  the  cooler. 

"Under  this  shield  are  holes  in  the  blast-pipe,  through  which  a 
constant  flow  of  fresh  air  is  maintained  by  means  of  a  fan,  the  air 
passing  out  of  the  cooler  through  holes  in  its  shell  the  latter  having 
conical  shields  on  the  inside  just  above  these  openings. 

"The  heat  of  the  clinker  is  absorbed  in  the  vaporization  of  the 
water  and  is  removed  by  the  current  of  air  which  passes  through  the 
thin  stream  of  clinker  moving  through  the  cooler  between  the  two  shields. 

"The  coolers  rest  on  a  cast-iron  plate,  supported  by  foundations 
4  feet  high,  in  a  pit  about  20  feet  below  the  kiln-room  floor.  Running 
under  these  coolers  are  belt  conveyors  which  receive  the  cooled  clinker 
(drawn  from  four  openings  in  each  cooler)  and  carry  it  to  the  boot  of 
an  elevator,  which  discharges  it  through  an  opening  in  the  wall  between 
the  kiln  room  and  the  clinker  ball-mill  department  onto  a  storage  floor." 

One-stage  rotary  cooler. — The  next  step  in  clinker-cooling  devices 
is  the  use  of  rotary  coolers.  These  are  simply  rotary  driers,  reversed 
in  action,  and  require  no  special  description  here. 

Atlas  two-stage  rotary  cooler. — By  far  the  most  satisfactory  of  cool- 
ing devices  is  the  two-stage  rotary  cooler  employed  by  the  Atlas  Port- 
land Cement  Company.  It  is,  so  far  as  the  writer  knows,  the  only 
cooling  system  which  really  cools  the  clinker  to  a  handling  temperature 
and  does  so  quickly  and  economically. 

The  cooling  system  at  the  main  Atlas  plant  was  described  by 
Stanger  and  Blount  in  1901  as  follows: 

"The  clinker  drops  from  the  burning  cylinder  into  a  second  rotating 
cylinder,  about  30  feet  long  and  3  feet  in  diameter,  revolving  about 
six  times  as  fast  as  the  burning  cylinder.  This  is  lined  with  fire-brick, 
and  through  it  passes  a  current  of  air  which  goes  to  feed  the  flame  of 
burning  coal-dust.  The  greater  part  of  the  sensible  heat  in  the  clinker 
is  thus  saved  and  utilized.  The  clinker,  still  moderately  hot,  falls  on 
to  three  crushing  rolls  contained  in  a  housing  and  moistened  by  a  spray 
of  water.  As  shown  in  the  figure  a  pair  of  kilns  with  their  accompany- 
ing first  cooling  cylinders  converge  so  as  to  deliver  the  clinker  onto 
these  rolls  and  from  this  point  a  single  secondary  cooling  apparatus 
serves  this  pair  of  kilns.  The  object  of  the  rolls  is  to  crush  large  lumps 
of  clinker  which  may  have  been  formed  by  the  aggregation  of  a  num- 
ber of  small  fragments  adhering  together  when  plastic  in  the  burning 


530 


CEMENTS,  LIMES,  AND  PLASTERS. 


cylinder.  These  lumps  being  built  up  of  small  pieces  loosely  stuck 
together  differ  entirely  from  the  tough  hard  masses  formed  in  a  fixed 
kiln  fed  with  blocks  or  bricks  of  raw  material,  and  are  readily  broken 
up  to  the  size  of  a  hazelnut.  The  warm  moist  clinker  passes  down  a 
third  rotating  cylinder  60  feet  long  by  5  feet  in  diameter,  lined  with 
hard  cast-iron  plates  provided  •  with  shelves  so  as  to  toss  and  tumble 
the  pieces  as  they  creep  down.  Air  is  drawn  in  through  this  cylinder 
by  means  of  a  chimney  which  also  carries  off  the  water  vapor  from 
the  housing  of  the  rolls.  It  is  intended  that  the  clinker  shall  emerge 


ELEVATION 


rm               r 

-1 

—  i      , 
.j 

T" 

Ih  Burning  Cylinder  { 

1 

i^tjii)a|H 

f 

uJ                      Hi 

nji             rp 

j  1    |  Burning  Cylinder  { 

! 

.r~-^ 

"    *- 

i£j                  L 

il 

T1 
I 

U- 


•Cruahing  Rolla 


PLA.N 

FIG.  132. — Atlas  rotary  two-stage  coolers.     (Engineering  News.) 

from  the  end  of  the  last  cooling  cylinder,  in  a  slightly  moist  condition, 
and  to  ensure  this,  regulation  of  the  water  at  the  rolls  is  supplemented 
by  a  small  jet  at  the  end  of  the  last  cooler." 

This  system  is  shown  in  Fig.  132,  taken  from  the  paper  *  below  cited. 

Clinker-grinding. 

After  cooling  sufficiently  to  be  workable,  the  clinker  passes  to  the 
clinker-grinding  department  of  the  mill.  The  problem  before  this 
department  is  to  reduce  large  quantities  of  an  intensely  hard  and  semi- 
vitrified  material  to  finely  ground  cement  at  the  lowest  cost  possible. 
This  reduction  is  now  usually  accomplished  in  two  or  three  stages. 

*  Stanger,  W.  H.,  and  Blount,  B.  The  rotary  process  of  cement-manufacture. 
Proc.  Inst.  Civil  Engineers,  vol.  145,  pp.  57-68.  1901.  See  especially  p.  62  for 
coolers. 


CLINKER  COOLING,  GRINDING,  AND  STORAGE.  531 

Somewhere  in  the  process  it  is  necessary  to  provide  for  the  addition 
of  a  certain  comparatively  small  percentage  of  gypsum  or  plaster,  in 
order  to  bring  the  setting  properties  of  the  cement  up  to  commercial 
requirements.  Though  this  addition  is  commonly  made  during  the 
grinding  process,  it  will  be  discussed  later  in  the  chapter. 

The  power  allowed  and  machinery  installed  for  pulverizing  the 
clinker  at  a  Portland-cement  plant  using  the  dry  process  of  manu- 
facture are  very  closely  the  same  as  that  required  for  pulverizing  the 
raw  materials  for  the  same  output.  This  may  seem,  at  first  sight, 
improbable,  for  Portland-cement  clinker  is  much  harder  to  grind  than 
any  possible  combination  of  raw  materials;  but  it  must  be  remembered 
that  for  every  barrel  of  cement  produced  about  600  Ibs.  of  raw  materials 
must  be  pulverized,  while  only  a  scant  400  Ibs.  of  clinker  will  be  treated, 
that  the  large  crushers  required  for  some  raw  materials  can  be  dis- 
pensed with  in  crushing  clinker,  and  that  the  raw  side  rarely  runs  full 
time.  The  raw  material  side  and  the  clinker  side  of  a  dry-process  Port- 
land-cement plant  are,  therefore,  usually  almost  or  exactly  duplicates. 

The  difficulty,  and  in  consequence  the  expense,  of  grinding  clinker 
will  depend  in  large  part  on  the  chemical  composition  of  the  clinker 
and  on  the  temperature  at  which  it  has  been  burned.  The  difficulty 
of  grinding,  for  example,  increases  with  the  percentage  of  lime  carried 
by  the  clinker,  because  of  the  higher  burning  which  has  been  necessary, 
and  a  clinker  containing  64  per  cent  of  lime  will  be  very  noticeably 
more  resistant  to  pulverizing  than  one  carrying  62  per  cent  of  lime. 
So  far  as  regards  burning,  it  may  be  said  in  general  that  the  more  thor- 
oughly burned  the  clinker  the  more  difficult  it  will  be  to  grind,  assuming 
that  its  chemical  composition  remains  the  same. 

The  tendency  among  engineers  at  present  is  to  demand  more  finely 
ground  cement.  While  this  demand  is  doubtless  justified  by  the  results 
of  comparative  tests  of  finely  and  coarsely  ground  cements,  it  must  be 
borne  in  mind  that  any  increase  in  fineness  of  grinding  means  a  decrease 
in  the  product  per  hour  of  the  grinding-mills  employed,  and  a  conse- 
quent increase  in  the  cost  of  cement.  At  some  point  in  the  process, 
therefore,  the  gain  in  strength  due  to  fineness  of  grinding  will  be  counter- 
balanced by  the  increased  cost  of  manufacturing  the  more  finely  ground 
product. 

The  increase  in  the  required  fineness  has  been  gradual  but  steady 
during  recent  years.  Most  specifications  now  require  at  least  90  per 
cent  to  pass  a  100-mesh  sieve;  a  number  require  92  per  cent;  while 
a  few  important  specifications  require  95  per  cent.  Within  a  few  years 
it  is  probable  that  almost  all  specifications  will  go  as  high  as  this. 


532  CEMENTS,  LIMES,  AND  PLASTERS. 

The  following  description  of  the  clinker-grinding  side  of  the  plant 
of  the  Hudson  Portland  Cement  Co.  has  recently  appeared  in  Engineer- 
ing News.  The  layout  of  this  plant  is  shown  in  Fig.  85,  p.  407: 

"The  kilns  are  60  feet  long  and  6  feet  in  diameter,  and  each  is  driven 
by  a  7^-H.P.  electric  motor.  Fig.  4  is  a  view  of  the  under  side  of  the 
kilns  showing  the  rolls  on  wrhich  they^un.  The  immense  size  of  these 
modern  cement  burners  is  excellently  indicated  by  this  illustration. 
From  the  kilns  the  clinker  is  run  into  rotary  coolers.  There  are  five 
of  these,  one  for  each  pair  of  kilns.  In  these  coolers  tjie  clinker  is  cooled 
by  a  current  of  air  which  is  blown  in  at  the  forward  ends  and  passes 
out  of  the  rear  ends  into  the  trunk  mains  whence  the  air-pipes  to  the  kilns 
branch  off.  The  coal  is  thus  blown  into  the  kilns  by  heated  air.  From 
each  cooler  the  clinker  drops  into  a  clinker  pit  and  from  these  pits  the 
elevators  G  hoist  it  to  the  bins  of  the  five  Krupp  ball  mills. 

"From  the  ball  mills  the  underground  screw  conveyor  14  and  the 
elevator  H  take  the  powder  to  the  double  hopper  where  the  final  adjust- 
ment of  proportions  is  made  if  necessary,  and  thence  the  conveyor  15, 
the  elevator  HH,  and  the  conveyor  16  take  the  powder  to  the  feed-bins 
of  the  seven  tube  mills,  for  final  grinding.  The  discharge  from  the 
tube  mills  is  taken  by  the  conveyor  16  J  to  conveyor  26,  which  leads 
to  the  storage-bins. 

"The  course  of  the  coal  through  the  drier  and  grinders  in  the  coal- 
grinding  room  and  thence  by  conveyor  24,  elevator  L,  and  conveyor 
26  to  the  powdered  coal-bins  for  the  kilns  can  be  readily  traced  from 
the  drawings,  and  need  not  be  explained  further  here." 

Actual  practice.  —  The  following  data  relate  to  the  machinery 
actually  used  on  the  clinker-grinding  side  of  a  number  of  American 
plants  and  will  serve  to  give  a  good  idea  of  present  practice  in  that 
line: 

Plant  No.    1.     Dry  process :  3  kilns,  about  450  barrels  per  day. 

1  small  jaw-crusher; 

2  ball  mills; 
2  tube  mills. 

Plant  No.     8.    Dry  process :  4  kilns,  about  700  bbls.  per  day. 

1  rotary  cooler;   - 

2  Smidth  ball  mills  to  8  mesh; 
1  Bonnot  ball  mill  to  30  mesh; 
4  tube  mills. 


CLINKER  COOLING,  GRINDING,  AND  STORAGE.  533 

Plant  No.    3.    Wet  process:  3  kilns,  about  240  bbls.  per  day. 
1  crusher; 

1  set  rolls; 

7  run  millstones; 

2  tube  mills. 

Plant  No.    4.    Wet  process:   13  kilns,  about  1300  bbls.  per  day. 

4  ball  mills; 

•    4  tube  mills. 
Plant  No.     5.    Wet  process :  3  kilns,  about  350  bbls.  per  day. 

3  Smidth  ball  mills,  No.  7; 

3  Davidsen  tube  mills,  No.  12. 

Plant  No.     6.    Dry  process:  6  kilns,  about  1200  bbls.  per  day. 
1  set  rolls; 

5  Bonnot  ball  mills; 

5  Bonnot  tube  mills. 

Plant  No.     7.    Wet  process :  5  kilns,  about  550  bbls.  per  day. 

1  rotary  cooler; 

2  Smidth  ball  mills,  No.  7; 

2  tube  mills. 

Plant  No.     8.    Wet  process :  14  kilns,  about  1200  bbls.  per  day. 

1  set  rolls; 

15  Griffin  mills. 
Plant  No.     9.    Wet  process :  6  kilns,  about  600  bbls.  per  day. 

3  ball  mills; 

3  tube  mills. 

Plant  No.  10.    Wet  process :  14  kilns,  about  1600  bbls.  per  day. 

2  rotary  coolers; 

6  ball  mills; 
6  tube  mills. 

Plant  No.  11.    Wet  process:  10  kilns,  about  1100  bbls.  per  day. 

4  ball  mills; 
4  tube  mills. 

Plant  No.  12.    Wet  process :  9  kilns,  about  1300  bbls.  per  day. 
1  roll-crusher; 
10  Griffin  mills; 

3  Griffin  mills. 

Plant  No.  13.    Dry  process :  3  kilns,  about  525  bbls.  per  day. 

1  crusher; 

2  ball  mills; 
2  tube  mills. 


534  CEMENTS,  LIMES,  AND  PLASTERS. 

Plant  No.  14.    Dry  process:   10  kilns,  about  1600  bbls.  per  day. 
7  ball  mills; 
7  tube  mills. 

Plant  No.  15.   Dry  process :   8  kilns,  about  1300  bbls.  per  day. 
4  ball. mills; 
6  tube  mills,     f* 

Plant  No.  16.    Dry  process :  6  kilns,  about  1000  bbls.  per  day. 
4  ball  mills; 
4  tube  mills. 

Plant  No.  17.    Dry  process:  6  kilns,  about  1200  bbls.  per  day. 
1  kominuter  and  3  ball  mills; 

4  tube  mills. 

Plant  No.  IS.    Wet  process:  21  kilns,  about  3000  bbls.  per  day. 

32  Griffin  mills. 
Plant  No.  19.    Dry  process :   10  kilns,  about  1700  bbls.  per  day. 

5  rotary   coolers; 

5  ball  mills; 

6  tube  mills. 

Plant  No.  20.   Wet  process:   10  kilns,  about  1400  bbls.  per  day. 

1  cracker; 

2  kominuters; 
5  tube  mills. 

Plant  No.  21.    Dry  process :  3  kilns,  about  450  bbls.  per  day. 

1  Williams  mill; 

2  tube  mills. 

Plant  No.  22.   Dry  process:  4  kilns,  about  700  bbls.  per  day. 

1  cracker; 

7  Griffin  mills. 

Plant  No.  23.   Dry  process :  2  kilns,  about  300  bbls.  per  day. 

2  ball  mills; 
2  tube  mills. 

Use  and  Effects  of  Gypsum  or  Plaster. 

The  high-limed  clinker  now  produced  in  the  rotary  process  is  nat- 
urally very  quick-setting.  In  order  to  retard  its  set  sufficiently  to  pass 
commercial  requirements,  sulphate  of  lime,  in  the  form  of  gypsum  or 
plaster,  is  now  universally  employed.  This  substance,  when  added 
in  quantities  up  to  2  to  3  per  cent,  retards  the  set  of  the  cement  pro- 
portionately, and  also  increases  somewhat  its  tensile  strength  in  short 


CLINKER  COOLING,  GRINDING,  AND  STORAGE.  535 

time  tests.  In  larger  quantities,  its  retarding  influence  becomes  less, 
and  finally  negative,  while  a  decided  weakening  of  the  cement  is  notice- 
able. 

The  more  theoretical  part  of  the  discussion,  relating  to  the  form  in 
which  the  sulphate  is  applied,  and  the  influence  of  various  percentages 
of  sulphate  on  the  set  and  strength  of  the  cement,  will  be  first  presented : 
after  which  the  actual  methods  of  application,  with  analyses  of  gypsums 
and  plasters  used  in  practice,  will  be  discussed. 

Form  in  which  calcium  sulphate  is  used. — The  requisite  calcium 
sulphate  may  be  added  to  the  cement  in  one  of  three  forms:  as  crude 
gypsum,  as  calcined  plaster,  or  as  dead-burnt  (anhydrous)  plaster. 
For  a  full  description  of  the  manufacture  and  properties  of  these  three 
products  the  reader  is  referred  to  Part  I  of  this  volume.  In  the  pres- 
ent place  their  essential  characters  can  be  briefly  stated  as  follows: 
Crude  gypsum  is  a  natural  hydrous  sulphate  of  lime,  corresponding  to 
the  formula  CaSO4+2H2O,  and  to  the  composition  calcium  sulphate 
79.1  per  cent,  water  20.9  per  cent.  Calcined. plaster,  or  plaster  of  Paris, 
is  obtained  by  heating  gypsum  at  temperatures  of  350°-400°  F.,  the 
result  being  that  three  fourths  of  the  combined  water  is  driven  off. 
The  resulting  plaster  has  the  formula  CaSC^  +  JH^O,  corresponding 
to  the  composition  calcium  sulphate  93.8  per  cent,  water  6.2  per  cent. 
If  gypsum  be  calcined  at  temperatures  much  above  400°  F.,  all  of  its 
combined  water  will  be  expelled,  leaving  dead-burnt  or  anhydrous 
plaster,  which  is  simply  CaSO*. 

Considerable  discussion  has  been  aroused  over  the  question,  which 
of  these  three  forms  of  calcium  sulphate  is  the  more  advantageous  for 
use:  but  few  satisfactory  series  of  experiments  are  on  record  in  regard 
to  this  point.  A  misleading  statement  often  made  is  that  plaster  of 
Paris,  because  of  its  greater  chemical  activity,  will  naturally  be  much 
more  effective  than  gypsum,  weight  for  weight.  The  fallacy  involved 
in  this  statement  is  revealed  when  it  is  considered  that  the  calcium 
sulphate  added  to  the  cement  has  absolutely  no  effect  until  the  mixture 
is  gauged  with  water;  and  that  this  addition  of  water  will  naturally 
reconvert  the  plaster  immediately  into  the  hydrous  lime  sulphate, 
gypsum.  Any  argument  based  on  relative  chemical  activity,  so-called, 
is  therefore  fallacious. 

The  results  of  a  few  recorded  experiments,  on  the  comparative  effects 
of  the  various  forms  of  calcium  sulphate,  on  the  set  and  strength  of 
the  cement,  will  be  given  below:  after  which  the  conclusions  which 
may  be  drawn  from  these  experiments  and  from  commercial  conditions 
and  actual  practice  will  be  summarized. 


536 


CEMENTS,  LIMES,  AND  PLASTERS. 

Neat,  52  weeks 


1  2 

Per- cent  of  plaster " 

t IG.  133. — Effect  of  plaster  on  strength;   different  ages  and  compositions. 

(Dyckerhoff.) 


CLINKER  COOLING,  GRINDING,  AND  STORAGE. 


537 


Nihoul  and  Dufossez,  in  the  course  of  the  experiments  described 
on  page  540,  tested  the  comparative  effect  of  calcium  sulphate  in  four 
different  forms — i.e.,  as  crude  gypsum,  as  calcined  plaster,  as  anhydrous 
plaster  and  as  chemically  precipitated  calcium  sulphate.  Their  con- 
clusions were:  (1)  that  with  the  precipitated  calcium  sulphate  and  cal- 
cined plaster  the  retardation  of  set  is  proportional  to  the  amount  of 
sulphate  added:  and,  (2)  that  with  crude  gypsum  this  is  true  only 
when  less  than  2  per  cent  of  gypsum  is  employed,  larger  percentages 
causing  acceleration  rather  than  retardation  of  set. 

Lewis  has  carried  out  a  short  series  of  experiments  on  the  influence 
of  calcium  sulphate  on  the  strength  of  the  cement,  applying  the  cal- 
cium sulphate  in  three  different  forms — gypsum,  plaster  of  Paris,  and 
anhydrous  plaster.  The  results,  given  in  the  table  below,  are  not  de- 
cisive: but  seem  to  show  a  somewhat  greater  regularity  of  effect  when 
plaster  of  Paris  or  anhydrous  plaster  are  used  than  when  gypsum  is 
employed. 

TABLE  197. 
EFFECT  OF  FORM  OF  SULPHATE  USED.     (LEWIS.) 


Amount  Added. 

Tensile  Strength,  7  Days  Neat. 

Tensile  Strength,  7  Days,  3:1. 

Anhydrous 
Sulphate. 

Plaster  of 
Paris. 

Crude 
Gypsum. 

Anhydrous 
Sulphate. 

Plaster  of 
Paris. 

Crude 
Gypsum. 

0    per  cent 

444 

444 

589 
651 
729 
524 
247 
254 

444 

196 

196 
212 
215 
225 
165 
66 
63 

196 

179 
194 
179 

li 

2 

647 

673 
541 
533 
593 

3                   

4                   

663 
293 

148 
127 

5                   

6                   

To  summarize  the  matter:  The  active  retarding  agent  is  the  sul- 
phur trioxide  present  in  the  gypsum  or  plaster.  As  anhydrous  plaster 
and  plaster  of  Paris  both  contain  somewhat  higher  percentages  of  SOa 
than  gypsum,  they  will  exercise  a  proportionally  greater  retarding 
effect,  weight  for  weight,  than  will  gypsum.  But  for  ordinary  practice 
this  slight  advantage  is  immensely  counterbalanced  by  the  fact  that 
gypsum  costs  usually  less  than  half  as  much  as  either  of  the  plasters: 
and  for  ordinary  practice,  therefore,  gypsum  is  the  only  form  of  cal- 
cium sulphate  that  can  be  considered  available.  In  certain  plants, 
however,  where  the  sulphate  is  added  after  the  cement  has  been  ground, 
it  is  necessary  to  use  plaster  of  Paris;  because  gypsum  as  bought  is 
ground  too  coarsely  to  add  to  a  finely  pulverized  cement. 


538 


CEMENTS,  LIMES,  AND   PLASTERS. 


Effect  of  calcium  sulphate  on  set  of  cement. — Experiments  on  the 
effect  of  setting  time  of  the  addition  of  gypsum  or  plaster  are  fairly 
numerous.  Unfortunately,  such  records  mean  very  little,  unless  they 
are  accompanied  by  sufficient  data,  as  to  the  chemical  composition, 


3  4 

Per  cent  of  Plaster. 

FIG.  134. — Effect  of  plaster  on  tensile  strength  of  Portland  cement.     (Lewis.) 

fineness,  etc.,  of  the  cement;  to  enable  some  idea  to  be  formed  con- 
cerning the  general  type  of  cement  tested.  Experiments  on  low-limed 
cement  can  not  be  fairly  compared  with  those  carried  out  on  high-limed 
cements;  and  cement  made  in  stationary  kilns  behaves  differently  from 
the  usual  product  of  the  rotary. 


CLINKER   COOLING,  GRINDING,  AND  STORAGE.  539 


2  3 

Plaster,  in  per  cents 

FIG.  135. — Effect  of  plaster  on  setting-time  of  Portland  cement. 
(Dyckerhoff's  tests;  Nihoul's  tests.) 


540 


CEMENTS,  LIMES,  AND  PLASTERS. 


In  the  experiments  *  of  Nihoul  and  Dufossez  a  commercial  Portland 
cement  of  the  following  composition  was  used: 

Silica  (SiO2) 22.80 

Alumina  (Al2Oj,) 7 . 79 

Iron  oxide  (Fe2O3) 1  -27 

Lime  (CaO) ".' . ' ? 65.80 

Magnesia  (MgO) 0 . 59 

Carbon  dioxide  (CO2) 1 .36 

Water 0.20 

It  is  to  be  noted  that  this  cement,  though  probably  made  in  a  sta- 
tionary kiln,  is  very  high-limed  and  correspondingly  quick-setting. 
It  can  therefore  be  considered  as  closely  similar  to  the  average  rotary 
clinker. 


FIG.  136.  f— Effect  of  plaster  on  setting-time.     (Sab in.) 


TABLE  198. 

EFFECT  OF  ADDING  VARIOUS  PERCENTAGES  OF  CALCINED  PLASTER. 
(NlHOUL  AND  DUFOSSEZ.) 


Composition. 


Pure  cement  .................. 

Cement  with  1    per  cent  plaster. 

- 


C  ( 

«          it 

«  « 

it  H 

(t  If 


Initial  Set.  Final  Set. 

Hours.  Minutes.  Hours.  Minutes, 


8 
10 
40 

7 
51 

0 
33 


13 
20 
0 
32 
50 
10 
12 


*  Journ.  Soc.  Chem.  Industry,  vol.  21,  pp.  859-860.     1902. 
tFrom  Johnson's  "Materials  of  Construction",  p.  187. 


CLINKER  COOLING,  GRINDING,  AND  STORAGE. 


541 


TABLE  199. 
EFFECT  OF  CALCINED  SULPHATE  ox  SET  OF  CEMENT.     (DYCKERHOFF.) 


Per  Cent  Plaster 
Added. 

Setting-time, 
Hours.  Minutes. 

0 

0 

20 

1* 

3 

30 

1 

10 

0 

2 

14 

0 

Results  obtained  by  Dyckerhoff  *•  are  given  in  the  table  above. 
It  is  unfortunate  that  no  analysis  of  the  cement  experimented  on  is- 
obtainable,  in  view  of  the  remarkably  great  retardation  effected  by 
very  small  percentages  of  sulphate. 

A  very  unusual  set  of  results,  obtained  in  experiments,  by  Messrs. 
Kniskern  and  Gass,  has  recently  been  published  f  by  Prof.  R.  C.  Car- 
penter. Clinker  was  procured  from  a  cement-plant  in  unground  form 
and  ground  in  the  laboratory,  being  mixed  with  various  percentages 
of  gypsum.  The  results  are  as  follows : 

TABLE  200. 
EFFECT  OF  GYPSUM  ON  SETTING-TIME.     (KNISKERN  AND  GASS.) 


Per  Cent 
Gypsum, 

Initial  Set, 
Minutes. 

Final  Set, 
Minutes. 

Per  Cent 
Gypsum. 

Initial  Set, 
Minutes. 

Final  Set, 
Minutes. 

0 

2 

52 

4 

28 

45 

| 

6 

87 

4$ 

22 

40 

i| 

80 

157 

5 

27 

59 

2 

24 

114 

5J 

20 

78 

2i 

29 

79 

6 

19 

37 

3 

30 

69 

6| 

22 

40 

3* 

27 

72 

18 

59 

These  results  are  shown  diagrammatically  in  Fig.  137  and  compari- 
son of  this  curve  with  those  of  Figs.  135  and  136  will  show  their  unique- 
character.  The  maximum  effect  was  obtained  with  1J  per  cent  of 
gypsum,  and  a  rapid  decrease  in  effect  was  shown  when  2  per  cent  or 
more  was  used.  Unfortunately  no  analysis  is  given  of  the  cement 
experimented  on,  so  that  we  cannot  judge  whether  or  not  there  is  any 
reason  for  these  curious  results. 


*  Proc.  Inst.  Civ.  Engrs.,  vol.  62,  p.  156.     1880. 

t  Engineering  News,  vol.  53,  pp.  13-14.     Jan.  5,  1905. 


542 


CEMENTS,  LIMES,  AND  PLASTERS. 


2345 
Per  cent  of  plaster 

FIG.  137. — Effect  of  plaster  on  setting-time  of  Portland  cement. 
Kniskern  and  Gass,  1905. 


CLINKER  COOLING,  GRINDING,  AND   STORAGE. 


543 


Effect  of  calcium  sulphate  on  strength  of  cement. — In  addition  to 
retarding  the  set  of  the  cement,  gypsum  or  plaster  exerts  an  interesting 
influence  on  its  strength  and,  in  some  cases,  its  soundness. 


0  1.0  2.0  3.0 

PERCENTAGE  OF  PLASTER  PARIS 


FIG.  138.* — Effect  of  plaster  on  strength  of  1:3  mortar.     (Tetmajer.) 

TABLE  201. 
EFFECT  OF  CALCIUM  SULPHATE  ON  STRENGTH  OF  CEMENT.     (DYCKERHOFF.) 


Percent- 
age 
Gypsum. 

Time  of  Set. 
Hrs.     Min. 

Neat  Cement. 

1  Cement  :  3  Sand. 

Week. 

4 
Wks. 

12 
Wks. 

25 
Wks. 

52 
Wks. 

1 
Week. 

4 
Wks. 

12 
Wks. 

26 
Wks. 

52 
Wks. 

0 

1 

2 

0      20 
3     30 
10       0 
14       0 

323 
315 
375 
425 

405 
456 
508 
543 

518 
572 
568 
688 

620 
623 

695 

718 

700 
650 

780 
805 

115 
142 
159 
180 

168 
212 
238 
263 

238 
339 
311 
305 

302 
353 
368 
375 

360 
390 
384 
410 

*  From  Johnson's  "Materials  of  Construction",  p.  187. 


544 


CEMENTS,  LIMES,  AND  PLASTERS. 


TABLE  202. 
EFFECT  OF  CALCIUM  SULPHATE  ON  STRENGTH  OF  CEMENT.     (GRANT.) 


Per  Cent  SO3 
Added. 

Neat  Cement. 

1   Cement  :  1   Sand. 

7  Days. 

30  Days. 

GO.Days. 

90  Days. 

v* 

7  Days. 

30  Days. 

60  Days. 

90  Days. 

0 

i 

313 
305 

500 

503 

536 

567 

605.4 
618.0 

106.8 
129.2 

159.2 
226.6 

188.4 
259.6 

266.8 
255.2 

TABLE  203. 
EFFECT  OF  TREATMENT  WITH  ANHYDROUS  CALCIUM  SULPHATE.     (LEWIS.) 


Tensile  Strength. 

Per  Cent 

Sulphate  Added. 

7  Days:   Neat. 

7  Days:   3:1. 

0 

444  Ibs. 

196  Ibs. 

2 

647  " 

4 

663  " 

148  " 

5 

293  " 

127  " 

TABLE  204. 
EFFECT  OF  TREATMENT  WITH  CRUDE  GYPSUM.     (LEWIS.) 


Per  Cent 

Tensile  Strength. 

Gypsum  Added. 

7  Days:  Neat. 

7  Days:   3:1. 

0 

444  Ibs. 

196  Ibs. 

2 

673  " 

3 

541   " 

179    " 

4 

533  " 

194  " 

5 

593  " 

179  " 

TABLE  205. 
EFFECT  OF  TREATMENT  WITH  PLASTER  OF  PARIS.     (LEWIS.) 


Tensile  Strength. 

Per  Cent  Plaster 

Added. 

7  Days:   Neat. 

7  Days:  3:1. 

0 

444  Ibs. 

196  Ibs. 

U 

589  " 

212  " 

2 

651   " 

215  " 

3 

729  " 

225  " 

4 

524  " 

165  " 

5 

247  " 

66  " 

6 

254  " 

63  " 

CLINKER  COOLING,  GRINDING,  AND   STORAGE. 


545 


Methods  cf  using  gypsum. — From  what  has  been  said  on  pre- 
ceding pages,  it  is  evident  that  in  Portland-cement  manufacture 
either  gypsum  or  burned  plaster  may  be  used  to  retard  the  set  of 
the  cement.  As  a  matter  of  fact,  gypsum  is  -the  form  almost  uni- 
versally employed  in  the  United  States.  This  is  merely  a  question 
of  cost.  It  is  true  that  to  secure  the  same  amount  of  retardation 
of  set  it  will  be  necessary  to  add  a  little  more  of  gypsum  than  if 
burned  plaster  were  used;  but,  on  the  other  hand, 'gypsum  is  much 
cheaper  than  burned  plaster. 

The  addition  of  the  gypsum  to  the  clinker  is  usually  made  before 
it  has  passed  into  the  ball  mill,  kominuter,  or  whatever  mill  is  in  use 
for  preliminary  grinding.  Adding  it  at  this  point  secures  much  more 
thorough  mixing  and  pulverizing  than  if  the  mixture  were  made  later 
in  the  process.  At  some  of  the  few  plants  which  use  plaster  instead 
of  gypsum,  the  finely  ground  plaster  is  not  added  until  the  clinker  has 
received  its  final  grinding  and  is  ready  for  storage  or  packing. 

Analyses  cf  gypsum  used. — The  following  analyses  will  serve  to 
illustrate  the  composition  of  the  crude  gypsum  and  of  the  calcined 
plaster  used  at  different  American  Portland-cement  plants. 

TABLE  206. 
ANALYSES  OF  GYPSUM  USED  IN  CEMENT-PLANTS. 


Silica  (SiO2)  

0  32 

0  86 

] 

(n.  d. 

Alumina  (A12O3)      

\  5  10 

7.26 

n.  d. 

Iron  oxide  (Fe2O3)  

|  0.87 

0.36 

J 

n.  d. 

Lime  (CaO)   

31  94 

30.84 

n   d. 

n.  d. 

35.8 

Magresia  (MgO) 

0  52 

Sulphur  trioxide  (SO3) 

44  93 

43  60 

40  20 

43  20 

43  6 

Carbon  dioxide  (CO2) 

Water 

20  95 

21  68 

n   d 

n   d 

20  3 

TABLE  207. 
ANALYSES  OF  CALCINED  PLASTER  USED  AT  CEMENT-PLANTS. 


Silica  (SiO2)              

0  83 

1   10 

n  d 

Alumina  (A10O3)     

>    0.46 

0.32 

n.  d. 

Lime  (CaO)        

38.58 

37  87 

37  26 

Magnesia  (M^O)  

0.50 

0.73 

1  11 

Sulphur  trioxide  (SO2)   

54.12 

53  26 

50  50 

Carbon  dioxide  (CO2)      

n.  d. 

n  d 

3  40 

Water 

5  61 

6  32 

5  50 

Effect  of  various  salts  on  set  of  cement. — Experiments  have  been 
made  on  the  use  of  various  other  salts — sulphates,  phosphates,  chlorides, 
etc. — by  different  chemists.  Few  of  the  results  thus  obtained  are  of  any 


546 


CEMENTS,  LIMES,  AND  PLASTERS. 


practical  importance,  for  most  of  the  salts  experimented  with  are  too 

costly  for  use. 

TABLE  208. 
EFFECT  OF  VARIOUS  SALTS  ON  SET  OF  CEMENT.     (NmouL  AND  DUFOSSEZ.) 


f 

Initial 
Hrs. 

Set. 
Min. 

Final  Set. 
Hrs.     Min. 

Pure  ceme 
Cement  w 

>nt 
ith 

t 

( 

0 

2 

8  ' 

0 
0 
0 

8 

7 
3 
3 
8 
1 
5 

0 
6 
0 
0 
0 
0 
0 

13 
32 
5 

4 
18 
3 

2p 

2 
2 
2 
2 

er  c( 

jnt  calcium  sulphate  
'     strontium  sulphate  
'     barium  sulphate          

'     calcium  phosphate     

'  '        aluminate  

'     precipitated  silica  

Recent  experiments  on  the  use  of  solid  chloride  of  lime  as  a  retarder 
have  been  published  by  Carpenter.  These  were  carried  out  by  the  same 
experimenters,  and  probably  on  the  same  cement  which,  when  treated 
with  gypsum,  gave  the  erratic  results  noted  on  p.  541.  Carpenter  sum- 
marizes *  these  experiments  as  follows: 

"Messrs.  Kniskern  and  Gass,  in  the  Sibley  Laboratory,  ground  differ- 
ent percentages  of  chloride  of  calcium  (CaCl2)  with  cement  clinker  and 
afterwards  made  pats,  using  in  each  case  simply  enough  water  to  give 
the  material  its  normal  consistency  for  this  purpose.  Their  results 
show  that  the  chloride  of  calcium  had  great  effect  in  retarding  the  time 
of  setting  and  exerted  the  greatest  effect  when  about  0.5  per  cent  by 
weight  of  the  chloride  of  calcium  was  employed.  On  account  of  the 
water  required,  1  per  cent  of  the  chloride  of  calcium  would  correspond 
approximately  to  gauging  with  a  solution  of  30  grams  per  liter  in  the 
previous  experiments  quoted. 

•  CaCl2  GROUND  DRY  WITH  THE  CLINKER. 


Per  Cent 
of  CaCl2. 

Per  Cent 
of  Water. 

Initial  Set, 
Minutes. 

Final  Set, 
Minutes. 

0.0 

29.8 

.     2 

52 

0.5 

34.1 

115 

274 

1.0 

29.8 

160 

272 

1.5 

26.4 

167 

234 

2.0 

25.4 

127 

212 

2.5 

26.4 

103 

180 

3.0 

26.4 

45 

182 

3.5 

26.4 

97 

185 

4.5 

28.6 

63 

150 

5.0 

29.8 

73 

160 

5.5 

29.8 

76 

84 

6.0 

29.8 

68 

145 

*  Engineering  News,  vol.  53,  pp.  13-14.     Jan.  5,  1905 


CLINKER  COOLING,  GRINDING,  AND  STORAGE.  547 

"The  experiments  quoted  indicate  that  chloride  of  calcium  added 
in  small  percentages  either  to  the  ground  clinker  as  a  powder  or  mixed 
with  the  water  for  gauging  has  an  important  effect  in  extending  the 
time  of  setting  of  Portland  cement,  and  so  far  as  the  investigations 
which  are  accessible  show  it  does  not  have  any  detrimental  effect  on  the 
permanent  strength  and  hardness. 

"Chloride  of  calcium  is  a  deliquescent  material  which  rapidly  ab- 
sorbs moisture,  and  it  is  possible  that  if  ground  dry  with  the  Port- 
land-cement clinker,  even  to  the  amount  of  J  per  cent,  it  would  cause 
the  material  to  gather  dampness  and  thus  have  a  bad  effect.  The 
chloride  of  calcium  solution  can  be  added  readily  by  adding  it  to  the 
water  used  in  gauging,  since  it  dissolves  with  extreme  rapidity.  The 
experiments  indicate  that  the  set  can  be  controlled  by  using  less  than 
i  per  cent,  which  would  be  something  less  than  2  Ibs.  to  the  barrel  of 
Portland  cement.  Investigations  are  still  necessary  for  determining 
whether  the  effect  of  chloride  of  calcium  added  to  the  cement  before 
grinding  is  permanent  in  its  effects,  and  whether  if  ground  with  the 
cement  clinker  it  would  avert  any  detrimental  effect." 

List  of  references  on  use  of  calcium  sulphate,  chloride,  etc. 

Candlot.     Ciments  et  chaux  hydrauliques. 

Carpenter,  R.  C.     Recent  experiments  with  materials  which  retard  the  activity 

of  Portland  cement.    Engineering  News,  vol.  53,  pp.  13-14.    Jan.  5,  1905. 
Deval,  L.     Composition  of  sulpho-aluminate  of  lime  (in  hydraulic  cements). 

Bull,  de  la  Soc.  d'Encourag.  ITnd.  National,  vol.  5,  pp.  49-54.     1900. 

Abstract  in  Jou-  n.  Soc  Chem.  Industry,  vol.  19,  pp.  247-248. 
Deval,  L.     Action  of  sulphate  of  lime  on  cements.     Bull,  de  la  Soc.  d'Encourag. 

I'lnd.  National,  no.   101,  p.  784-787.     1901.     Abstract  in  Journ.  Soc. 

Chem.  Industry,  vol.  21,  p.  257. 
Deval,  L.     Influence  of  calcium  sulphate  on  cements.     Thonindustrie  Zeitung, 

vol.  26,  p.  913-915.     1902.     Abstract  in  Journ.  Soc.  Chem.  Industry, 

vol.  21,  pp.  971-972. 
Lewis,  F.  H.     Specifications  for  Portland  cements  and  cement  mortars.     Proc. 

Engrs  Club,  Phila.,  vol.  11,  pp.  310-346,     1894. 
Ljamin,  X      Abnormalities  in  the  initial  setting  of  cement.     Thonindustrie 

Zeitung,  vol.  26,  pp.  874-876.     1901.    Abstract  in  Jcurn.  Sec.  Chem. 

Industry  vol.  pp.  972-973. 
Nihoul,  E.,  and  Dufossez,  P.     Note  en  ohe  retardation  of  se+tine:  of  Portland 

cement.     Bull.  Scient.  de  1'Assoc.  des  Eleves  des  Ecoles  speciales  de 

Liege,  no.  3,     Abstract  in  Journ.  Soc.  Chem.  Industry,  vol.  21,  pp.  859- 

860. 
Rohland,  P.     Hydration  of  Portland  cement.     Zeits.  angew.  Chemie,  vol.  16, 

pp.  1049-1055.     1903.     Abstract  in  Journ.  Soc.  Chem.  Industry,  vol.  22, 

pp.  1244-1245. 


548  CEMENTS,  LIMES,  AND  PLASTERS. 


Storage,  Packing,  and  Market. 

Necessity  for  storage. — A  twofold  necessity  exists  for  large  storage 
space  at  a  modern  cement-plant.  The  cement  will  in  many  cases 
be  improved  by  storage,  particularly  if  it  can  be  so  stored  that  air  will 
gain  access  to  the  mass.  Aeration  in  tile  storage  building  is,  however, 
rarely  possible;  and  in  consequence  the  tendency  now  is  in  the  direction 
of  aerating  or  slaking  the  clinker  before  grinding.  The  main  reason 
for  storage  still  remains  prominent.  It  is  caused  by  the  fact  that  while 
the  average  mill  runs  twelve  months  in  a  year,  the  cement-selling  period, 
in  most  of  the  United  States,  is  practically  confined  to  six  months  or 
even  less.  This  of  course  necessitates  very  extensive  storage  facilities — 
enough  to  hold  at  least  three  months'  output  of  the  mill,  and  preferably 
to  hold  six  months'  production.  This  means  that  for  each  kiln  in  a  dry- 
process  plant,  storage  space  for  at  least  20,000  barrels  should  be  provided. 
As  Portland  cement  dumped  from  a  conveyor  will  pile  up  so  as  to 
weigh  about  90  to  100  Ibs.  per  cubic  foot,  the  storage  space  above  stated 
(20,000  barrels)  would  be  equivalent  to  about  80,000  cubic  feet  for  each 
kiln  in  the  plant.  This  is  the  minimum  of  space  that  can  be  given  with 
safety,  and  an  allowance  of  150,000  cubic  feet  per  kiln  would  be  much 
better  for  the  average  plant  in  the  Middle  or  Eastern  States.  In  the 
South  and  West  conditions  are  different,  and  much  less  storage  space  is 
required. 

Designs  of  storage  buildings  and  bins. — In  Figs.  139,  140,  141,  and 
142  are  given  plans  of  several  recently  erected  storage  buildings  and 
bins.  Those  shown  in  Fig.  139  are  concrete-steel  bins  erected  for  the 
Portland-cement  plant  of  the  Illinois  Steel  Co. 

The  stock-house  and  bins  shown  in  Figs.  140,  141,  and  142  are  those 
of  the  Hudson  Portland  Cement  Co.  In  a  description  of  that  plant 
accompanying  these  figures  *  the  following  data  are  given:  "The  stock- 
house  is  a  structure  410  feet  long  and  105  feet  wide,  having  as  founda- 
tions a  series  of  concrete  walls  founded  on  piles.  It  contains  three  groups 
of  twenty  bins  each.  The  bins  are  of  wood,  their  walls  being  laid  up 
solid  of  2"X10"  and  2"X8"  plank  laid  flat  and  spiked  together.  The 
total  capacity  of  the  bins  is  200,000  barrels  of  cement.  Cement  is  con- 
veyed to  the  stock-house  from  the  mill  by  means  of  conveyor  26,  which 
discharges  into  the  boot  of  elevator  0.  This  elevator  discharges  into 
the  transverse  screw  conveyor  27,  which  spouts  onto  two  belt  conveyors 

*  Engineering  News. 


vFRSHTY  OF  OALMW         **t 


±_ 


SECTIONAL  PLAN 

FIG.   139. — Concrete-steel  bins 


Monier  Roof  Platen 


VERTICAL  SECTION 


tool  Co.     (Engineering  News.) 

[r^  /ac^  /».  548. 


CLINKER  COOLING,  GRINDING,  AND  STORAGE. 


549 


running  lengthwise  of  the  building  over  the  bins.     From  these  belts 
the  cement  can  be  deflected  into  any  one  of  the  60  bins." 


CROSS  SECTION  OF  MACHINERY  BUILDING  AND  STOCK  HOUSE 


V-  —                              I—^T^I 

\ 

^^       -    •  •                y|ii 

TrusB^      ea^Q  *\~  ElevatoKiaVT'CuBii 

Elevator 
12"x7"Cup8 

c,A4S&|gU-«l  |     I 

rfra 

afej  i  bg 
i  .  i 

LONGITUDINAL  SECTION  OF  STOCK  HOUSE,  SHOWING  CONVEYORS  AND  ELEVATORS, 

rf  Sprocket 
ator 


DETAIL  OF  PASSAGE  WAY  BETWEEN  STOCK  HOUSE 
AND  MACHINERY  BUILDING 


PART  PLAN 


FIG.  140. — Plan  and  sections  of  stock-house,  Hudson  Portland  Cement  Co., 
showing  conveying  machinery.      (Engineering  News.) 

Testing  at  the  mill. — The  contents  of  each  bin  should  be  sampled 
as  soon  as  it  is  filled,  and  the  usual  physical  tests  made  on  these  samples, 
supplemented  by  analysis  if  need  be.  If  the  cement  is  weak  or  unsound, 
it  is  far  better  in  every  way  to  detect  it  at  the  mill  than  to  run  the  risk 
of  having  it  rejected  at  the  work.  The  results  of  these  tests  are  then 
forwarded  to  the  purchaser  with  each  shipment,  typical  blanks  for 
this  purpose  being  shown  on  page  550. 

Of  recent  years  it  has  become  the  fashion,  in  specifications  for  cement 
for  important  work,  to  require  that  the  purchaser  should  be  represented 
at  the  cement-mill  by  an  inspector  during  the  manufacture  and  ship- 
ment of  the  cement  covered  by  the  specifications.  This  practice,  if 


550 


CEMENTS,  LIMES,  AND  PLASTERS. 


Sn 

| 

.I 

1 

1 

1 

| 

1 

.s 

^s 

'. 

S 

V* 

pq 

• 

.  .  .  :  . 



ijj 

1 

B 

•1 

2 

1 

4 

.:: 

"o  ^ 

? 

5 

03 

•s 

£ 

•^ 

1 

Q 
i> 

i 

-4- 

o- 

§ 

"^3  ^ 

•§ 

0          EH' 

t-» 

1                                   G 

a 

•o    «  -f 
§o| 

<s 

02    S 

1  ^ 

^    ^     f 

' 

11  1 

1 

• 

S  S  J 

S  g  c 

1 

<u          G 

1 

;   ;  c   :   ;   ;  £  03   ; 

O       '.    02*          "S  to 

s^ 

1 

.s 

2 

1 

£ 

Iss  u 

1 

^ 

K 

G 

'3 

f.2  fl  ^         §   c3   c3 

2    02     S  jj            03    02    CO 

£'i 

50    g^g-      -g    »    M 

^7J: 

OH^ 

^  ^     Cl     ^            02    C3    C^ 

O    o3 

n 

.  .b<  t-i      t->  pt  pl 

C    02 

4 

'  £  ^   &,"     C   OJ  a; 

CO 

.-, 

H-PtNv.s.'^       ^      S       <U 

G 

>• 

^—  t  'T 

^^M        c^  C^I  ^O  i-^  t-C  ^^ 

a 

t^     "" 

^  ^P  fcCx^XN*-x%s~^'  "*^  ~*^   ^ 

C 

>                       G) 

IJ 

||f|:  :  If! 

£ 

a 

,T 

2            S 
i           S 

C 

•    -4- 

E 

ji  i 

c 

R 

-1-2    -I 

a 

3 

e 

c 

51  f 

far               ^ 

S 

rT  MM                                   9    c 

rt  -V 

i 

g 

2-?        M 

i—i              £ 

1 

?  ::! 

n    Vi                                         M    s 
j    O  -0)                                   __    C 

3  ^ 

0   C 

3 

C 

;  c 

d            i 
fi            ( 

SH                         1 

O 

•> 

r  : 

:J 

X    •   £ 
^    '-C 

2  e:~                        «  ^ 
g  2  g                       '-5  £ 
'SJ 

~^- 
:  - 

3.= 

o.= 

5 

i 
= 

:f      g- 

CLINKER  COOLING,  GRINDING,  AND  STORAGE. 


551 


taken  up  in  a  proper  spirit  by  both  sides,  will  prevent  many  difficulties 
and  misunderstandings. 

If  the  duties  of  such  an  inspector  are  to  be  properly  carried  out, 
however,  he  should  possess  a  somewhat  intimate  knowledge  of  the 
processes  of  cement  manufacture.  The  position  is,  moreover,  one  of 
extreme  delicacy,  and  it  offers  abundant  opportunity  for  bribery  on  the 
one  side  and  blackmail  on  the  other.  For  these  reasons  it  is  obvious 
that  a  mill-inspector  must  be  a  man  of  special  training  and  qualifica- 
tions and  unimpeachable  integrity.  As  a  matter  of  fact,  such  men  are 
rarely  obtainable  for  this  position,  and  the  inspector  is  usually  a  young 
engineer,  with  but  little  knowledge  of  the  points  which  it  is  necessary 
to  guard  against. 

Packing. — According  to  the  recently  issued  specifications  of  the 
American  Society  for  Testing  Materials,  quoted  later,  Portland  cement 
should  be  packed  in  bags  of  94  Ibs.  net  weight,  four,  of  which  make  a 
barrel  of  376  Ibs.  net.  Several  other  important  specifications  require  a 
barrel  of  375  Ibs.  net.  In  ordinary  calculations  it  is  often  assumed  for 

C.L.  of  Conveyor^ 


FIG.  141. — Foundation  plan  of  cement  stock-house,  Hudson  Portland  Cement  Co. 


Platform 


Platform        20  9^ 


KM'9%- 


FIG.  142. — Plan  of  bins  in  cement  stock-house,  Hudson  Portland  Cement  Co. 

convenience  that  a  barrel  of  Portland  cement  weighs  400  Ibs.  gross  or 
3SC  Ibs.  net.  The  following  table  (209),  published  some  years  ago  by 
Mr.  Sanford  Thompson,*  gives  the  results  of  a  series  of  actual  tests  on 
the  weight,  size,  etc.,  of  cement  barrels. 

*  Thompson,  Sanford  E.  Weights  of  Portland  cement  and  capacity  of  cement 
barrels.  Engineering  News,  Oct.  4,  1900.  For  a  more  detailed  discussion  of  the 
subject,  reference  should  be  made  to  Taylor  and  Thompson's  "Concrete,  Plain 
and  Reinforced",  1905,  pp.  216  et  seq. 


552 


CEMENTS,  LIMES,  AND  PLASTERS. 


TABLE 
CAPACITY  OF  PORTLAND-CEMENT  BARRELS  AND 


Number 
Barrels 
Tested  ; 
Results 
Aver- 
aged. 

Brand. 

Height 
between 
Heads, 
•    Feet. 

Average. 

Capacity 
Barrel 
between 
Heads, 
Cu.  Ft. 

Depres- 
sion, 
Cement 
below 
Head, 
Feet. 

Volume 
of  De- 
pression, 
Cu.  Ft. 

0.171 
0.059 
0.096 
0.093 
0.039 
0.235 
0.148 

Diam- 
etej  of 
Barrel, 
Feet. 

Hori- 
zontal 
Area, 
Sq.  Ft. 

6 
6 

3 
5 
1 
5 
5 

Giant  

2.19 
2.08 
2.07 
2.01 
2.13 
2.12 
2.01 

.430 
.403 
.412 
.407 
.38 
1.437 
1.455 

1.605 
1.546 
1.571 
1.554 
1.496 
1.622 
1.662 

3.495 
3.219 
3/249 
3.123 
3.186 
3.446 
3.327 

0.12 
0.04 
0.07 
0.07 
0.03 
0.17 
0.10 

Alsen 

Savior's 

Dyckerhoff 

Fiske  Lion  * 

Atlas                   .    .    . 

Aalborg  f         

Final  averages     

2.09 

1.418 

1.579 

3.292 

0.09 

0.120 

*  Hanover. 


t  Denmark. 


§  Partial  averages.          TO  be  compared  only 


At  present  a  very  large  proportion  of  American  cement  is  marketed 
in  sacks  or  bags,  packing  in  wood  being  almost  entirely  confined  to 
•cement  inteijded  for  export  or  coastwise  shipment.  Foreign  cement,  of 
course,  reaches  the  American  market  in  barrels,  but  imported  cements 
are  becoming  of  less  consequence  each  year. 

When  cement  is  packed  in  wood,  the  barrels  are  usually  charged  for 
at  a  rate  sufficient  to  give  a  slight  profit  to  the  packing  department  of 
the  mill.  Bags  and  sacks  are  also  charged  extra,  with  a  rebate  for  re- 
turned bags.  In  figuring  the  cost  of  cement  manufacture  it  is  there- 
fore unnecessary  to  include  the  actual  cost  of  the  packages,  but  the 
labor  and  power  used  in  the  packing-house  must  be  figured  in. 


CLINKER   COOLING,  GRINDING,  AND  STORAGE. 


553 


209. 
WEIGHT  OF  CONTENTS. 


(HOWARD  A.  CARSON.) 


Volume  of  Cement  per 
Barrel. 

Net  Weight  of 
Cement  per  Barrel 
at  Dumping. 

Weight  per  CubicFoot. 

Weight 

Barrel, 
Pounds. 

Packed, 
Cu.  Ft. 

Loose, 
Cu.  Ft. 

Shaken,  || 
Cu.  Ft. 

Before, 
Pounds. 

After, 
Pounds. 

Packed, 
Pounds. 

Loose, 
Pounds. 

Shaken, 
Pounds. 

Sifted, 
Pounds. 

3.347 
3.161 
3.152 
3.031 
3.147 
3.211 
3.206 

4.173 
4.192 
4.052 
3.989 
4.270 
3.754 
4.058 

3^522 
3.695 
3.432 
3.598 

381.0 
374.2 
387.0 
373.2 

378.0 
377.4 
370.7 

371  A 
378.0 
376.9 
370.2 

113.81 
118.45 
122.75 
123.16 
120.11 
117.54 
115.71 

91.38 
89.20 
94.24 
93.18 
88.52 
100.49 
91.40 

29.0 
24.3 
22.7 
25.6 
22 
21.1 
23.3 

105.54 

102.29 
109.45 
102.94 

90]6 
80.3 

3.179 

4.070 

3.562§ 

377.4 

374.  1§ 

118.79 

92.63 

105.  06§ 

85.  4§ 

24.0 

with  like  brands. 


II  Box  rocked  over  bar. 


Note. — Paper  weighs  about  1  Ib. 


CHAPTER   XXXVII. 
COSTS  AND  STATISTICS 

Costs  of  Manufacture  of  Portland  Cement. 

To  the  popular  mind  the  manufacture  of  Portland  cement  is,  though 
fccuiewhat  mysterious  in  process,  so  remarkably  cheap  as  to  be  a  very 
attractive  investment.  This  opinion  is  carefully  fostered  for  selfish 
purposes  by  many  so-called  "cement  experts"  and  " cement  engineers", 
men  of  a  class  comparable  with  the  "mining  experts"  who  infest  the 
Western  mining  districts  and  differing  in  degree  only,  not  in  kind,  from 
the  more  humble  green-goods  man  of  the  East.  Michigan,  especially, 
has  been  the  prey  of  this  class  of  cement  experts,  for  in  no  other  State 
has  so  much  money  been  sunk  by  comparatively  poor  people  in  the 
erection  of  unprofitable  Portland-cement  plants.  Many  of  these  com- 
panies have  been  reorganized  and  are  now  on  a  firm  basis,  but  the  amount 
of  money  thrown  away  by  ignorant  investors,  misled  by  lying  estimates 
and  prospectuses,  has  been  enormous. 

The  truth  of  the  situation  appears  to  be,  on  the  contrary,  that  there 
is  a  very  small  margin  of  profit  for  most  of  the  plants  now  engaged  in 
Portland-cement  manufacture.  It  is  probable,  indeed,  that  the  per- 
centage of  profit  In  the  lime  or  natural-cement  industries  is  far  greater 
than  in  the  average  Portland- cement  piant. 

In  the  following  pages  some  estimate  of  the  cost  of  Portland-cement 
manufacture  under  various  conditions  will  be  given. 

Factors  of  cost. — The  total  cost  of  manufacture  of  Portland  cement 
may  be  subdivided  as  follows: 

A.  Fixed  charges. 

(a)  Interest  on  cost  of  land  and  quarries; 

(6)  Interest  on  cost  of  construction  and  erection; 

(c)  Interest  on  reserve  capital  invested; 

(d)  Allowance  for  sinking  fund; 

(e)  Insurance  and  taxes. 

554 


COSTS  AND  STATISTICS,  555 

B.  Current  administrative  expenses. 

(a)  Salaries  of  administrative  officers; 

(b)  Expenses  of  sales  and  advertising  department. 

C.  Current  factory  costs. 

c  1.  Cement  materials; 

(a)  Raw  materials  \  2.  Coal; 

(.3.  Gypsum; 

(b)  Supplies  and  repairs; 

(c)  Labor; 

(d)  Mill-office  and  laboratory  expenses. 

Cost  of  land  and  quarries. — The  cost  of  land,  including  under  this 
head  both  the  land  on  which  to  locate  the  plant  and  also  the  land  con- 
taining the  supplies  of  raw  material,  is  naturally  the  most  >  variable 
item  of  the*  lot.  Much  will  depend  on  the  manner  in  which  the  nego- 
tiations are  conducted.  When  marl  lands  are  hunted  with  the  aid  of 
a  brass  band  and  a  press  bureau  prices  as  high  as  $40  per  acre  (contain- 
ing about  9  feet  of  workable  marl)  have  been  paid.  On  the  other  hand, 
lands  located  on  transportation  routes  and  underlaid  by  40  feet  of  lime- 
stone and  more  than  enough  shale  have  been  purchased  as  farming  land 
at  about  $5  per  acre,  the  seller  concealing  from  the  guileless  purchaser 
the  fact  that  the  soil  was  too  thin  for  good  farming.  In  the  Lehigh 
district,  where  little  cement  land  remains  unbought,  prices  varying 
from  $100  to  $500  per  acre  have  been  quoted,  but  I  have  no  means  of 
determining  the  true  average  value  of  land  in  this  district. 

Examination  of  a  number  of  prices  paid  for  land  by  cement-plants 
shows  that,  considering  both  area  and  workable  thickness,  the  price 
paid  usually  falls  between  J  and  ^  cent  per  cubic  yard  of  raw  material. 
Land  for  the  plant  itself  may  be  expensive,  for  good  mill-sites  are  scarce. 

In  this  connection  it  may  be  well  to  recall  some  estimates  previously 
made  on  the  amount  of  raw  material  required  by  a  plant.  It  was  stated 
that  each  kiln  of  a  dry-process  plant  will  use  about  190,000  cubic  feet  of 
limestone  per  year,  equal  to  a  thickness  of  4^  feet  over  an  acre,  plus 
80,000  cubic  feet  of  shale  or  clay,  equivalent  to  an  acre  2  feet  thick. 
A  wet-process  plant  will  use  about  450,000  cubic  feet  of  marl  (measured 
in  place)  plus  about  45,000  cubic  feet  of  clay  or  shale.  In  buying 
quarry  lands  for  a  new  plant,  at  least  a  twenty-year  supply  of  workable 
raw  material  should  be  secured. 

Cost  of  equipment  and  erection. — Exclusive  of  the  cost  of  land,  the 
cost  of  equipping  and  erecting  a  good  plant  will  usually  fall  within  the 
limits  of  $50,000  to  $80,000  per  kiln.  These  limits  may  seem  wide,  but 


536  CEMENTS,  LIMES,  AND  PLASTERS. 

it  is  difficult  to  make  a  closer  general  estimate.  Two  plants  recently 
built  cost  as  follows: 

4-kiln  plant,  total  cost.  . .   $287,000          Cost  per  kiln $71,750 

6-"       "          "       "    ...     373,000  "      "      "  62,167 

For  small  plants  of  2  to  6  kilns  each  such  costs  would  not  be  excep- 
tional. For  larger  plants  it"  is  to  be^  remembered  that  cost  per  kiln 
decreases  with  increase  in  the  number  of  kilns.  The  following  table 
of  average  costs  will  serve  to  exemplify  this  and  may  be  of  use  as  a  basis 
for  general  estimates : 

2-kiln  plant $70,000  to  $80,000  per  kiln 

4-"       "       60,000"     70,000    "      " 

6-"       "      50,000"     60,000    "      " 

8-"      "     or  over 45,000"     50,000    "      " 

The  distribution  of  this  total  throughout  the  plant  may  be  shown 
by  the  following  estimate  for  cost  of  construction  of  a  6-kiln  dry- 
process  plant: 

Quarry,  track,  and  trestle $15,000 

Crusher  and  mixing 22,100 

Raw  and  clinker  mills 63,640 

Kiln  mill 53,080 

Coal  mill 15,920 

Power-plant 63,000 

Stock-house 25,000 

Office,  laboratory,  etc 10,000 

$267,740 

Total  capital  required. — The  amount  of  capital  required  to  prop- 
erly float  a  cement  proposition  is  considerably  in  excess  of  the  costs 
of  land,  construction,  etc.  The  principal  causes  of  this  condition  are: 

(a)  It  is  within  bounds  to  say  that  the  average  cement-plant  will 
not  produce  a  normal  cement  at  a  normal  cost  for  a  considerable  period 
(varying  from  3  to  6  months  or  even  longer)  after  the  plant  h  first  put 
in  operation.  Both  the  machinery  and  the  personnel  of  the  plant 
will  require  numberless  (though  individually  small)  alterations  before 
good  work  can  be  accomplished.  The  plant  must  be  carried  through 
this  profitless  and  expensive  period  entirely  on  its  reserve  capital. 

(6)  It  is  becoming  more  and  more  the  fashion  among  engineers  to 
judge  a  cement  by  its  past  record,  and  to  refuse  bids  from  a  plant  not 
possessing  a  record  of  success  in  actual  work.  Even  after  the  plant 
is  working  normally,  therefore,  steady  sales  cannot  be  counted  on  for 
some  time.  The  intervening  time  can,  of  course,  be  devoted  to  filling 
large  stock-houses,  but  this  brings  in  no  ready  money  to  the  plant. 

(c)  Cement  is  sold  on  comparatively  long  time,  while  many  of  the 


COSTS   AND   STATISTICS.  557 

expenses  of  the  plant  must  be  paid  in  cash.  This  is  particularly  the 
case  with  regard  to  quarry  and  mill  labor,  an  item  which  alone  may 
amount  in  a  six-kiln  plant  to  from  $4000  to  $6000  per  month. 

For  these  reasons  it  is  advisable  to  make  a  very  liberal  allowance 
for  the  working  capital  required.  A  reserve  amounting  to  $20,000 
to  $25,000  per  kiln  will  probably  be  found  sufficient  to  cover  most  cases, 
though  in  commencing  work  on  absolutely  new  materials  a  consider- 
ably larger  reserve  will  be  found  advisable.  Adding  this  ncces~ary 
reserve  to  the  amount  required  for  the  purchase  of  land  and  the 
actual  erection  of  the  plant,  and  for  ordinary  small  plants,  it  will  be 
found  that  the  total  working  capital  necessary  will  be  in  the  neighbor- 
hood of  $100,000  per  kiln. 

Current  administrative  expenses. — This  group  of  expense  factors- 
includes  the  salaries  of  the  administrative  officers  of  the  plant  and 
also  the  expenses  of  the  sales  department,  including  advertising.  It 
is  obviously  one  of  the  most  variable  factors  in  the  cost  of  cement-man- 
ufacture as  between  different  plants.  Even  at  the  same  plant  it  may 
vary  widely  from  time  to  time,  because  its  total  amount  does  not  depend 
directly  upon  the  amount  of  cement  sold.  In  a  large  plant  during  a 
prosperous  year  the  costs  chargeable  to  this  group  of  expenses  may  fall 
as  low  as  5  cents  per  barrel  of  cement  produced,  while  in  a  small  plant 
running  undertime  they  may  easily  rise  as  high  as  15  cents  per  barrel. 

Cost  of  excavating  raw  materials. — This  point  has  been  covered 
quite  fully  on  preceding  pages.  In  the  present  place  it  will  only  be 
necessary  to  summarize  this  information  by  stating  that  the  total  cost 
of  raw  materials,  delivered  at  the  mill,  per  barrel  of  cement  produced, 
will  usually  fall  within  the  following  limits : 

Cost  per  Barrel. 


Cement  rock  and  limestone. . 
Pure  limestone  and  clay.  .  .  . 


Marl  and  clay  or  shale. 


a.  Limestone  on  property .  .    $0 . 07  to  $0 . 10 

b.  Limestone  purchased  ...        .15 


a.  Quarried 06 

b.  Mined 10 

a.  Both  on  property 03 

b    Clay  purchased 08 


.20 
.15 
.20 
.05 
.15 


Total  power  required. — The  total  power  developed  in  a  Portland- 
cement  plant  is  not  far  from  1  H.P.  for  each  barrel  of  cement  turned 
out  per  day.  As  most  of  the  power  is  required  continuously,  it  is  &afe 
to  figure  on  a  requirement  of  20  to  30  H.P.-hours  for  each  barrel  of 
cement.  This  will  include  the  power  used  in  grinding  and  mixing  the 
raw  materials  in  running  conveyors,  kilns,  etc.,  and  in  grinding  the 
clinker. 

At  most  American  plants  all  this  power  is  derived  from  the  direct 
consumption  of  coal  under  boilers.  At  several  plants,  however,  water 


558 


CEMENTS,  LIMES,  AND   PLASTERS. 


power  is  used  with  electric  transmission;  in  at  least  one  plant  natural 
gas  is  used,  partly  in  gas-engines  and  partly  under  boilers,  and  in  a 
few  plants  part  of  the  power  is  derived  from  the  waste  gases  of  the  kilns. 

Cost  of  coal  for  kilns  and  power. — The  total  amount  of  coal  used 
per  barrel  of  cement,  both  under  the  boilers,  in  driers,  and  in  the  kilns, 
may  vary  from  170  Ibs.  in  a-'Lehigh-dis.trict  plant  using  long  kilns  to  300 
or  350  Ibs.  in  a  wet-process  plant.  Even  this  latter  figure  is  exceeded  at 
times,  for  one  wet-process  plant  recently  reported  a  total  coal  consump- 
tion of  over  400  Ibs.  per  barrel. 

Cost  of  gypsum  used. — The  amount  of  gypsum  or  plaster  used  in 
a  large  plant  is  quite  an  item,  as  8  to  14  Ibs.  may  be  used  per 
barrel  of  cement.  Crude  gypsum  in  small  lumps  may  be  bought  as 
low  as  80  cents  or  so  per  ton  when  the  cement-plant  is  located  in  a  gyp- 
sumrproducing  district.  On  the  other  hand,  burned  plaster  plus  freight 
may  cost  as  high  as  $6  to  $10  per  ton  for  a  plant  not  so  near  the 
source  of  supply.  Assuming  that  on  the  average  10  Ibs.  of  gypsum  or 
plaster  are  used  in  each  barrel  of  cement,  these  prices  would  make  the 
cost  per  barrel  of  cement  range  from  J  cent  to  5  cents.  At  most  of  the 
plants  in  this  country  the  gypsum  cost  will  probably  range  between 
1  and  2  cents  per  barrel  of  cement. 

Distribution  and  cost  of  labor. — The  following  statement*  of  the 
distribution  and  amount  of  labor  in  a  six-kiln  Lehigh-district  plant  has 
recently  been  published.  The  number  of  men  given  are  those  actually 
employed  in  one  twenty-four-hour  day  (two  shifts),  and  the  cost  per 
barrel  has  been  based  on  an  output  of  1200  barrels  per  day. 

TABLE  210. 
LABOR  COSTS  IN  CEMENT-PLANT. 


Location. 

Number 
of  Men. 

Labor  Cost 
per  Barrel. 

Stone  house  
Raw  mill   . 

4 
6 

$0.005 
0075 

Coal  mill  

6 

01 

Kiln-room 

8 

015 

Clinker  mill  

6 

0075 

Boiler-room 

4 

0075 

Engine-room 

4 

0075 

Yard  o'ano: 

13 

015 

Repair  gang  
Packing-house  

13 
30  f 

.0225 
04 

94 

$0.1375 

*  Boilleau  and  Lyon.     Cost  of  building  and  operating  a  Portland-cement  plant. 
Municipal  Engineering,  vol.  26,  pp.  391-395.     June,  1904. 
f  Contract  work  (estimated). 


COSTS  AND  STATISTICS. 


559 


The  total  labor  costs  given  in  the  footing  of  the  above  table  may 
profitably  be  compared  with  those  of  two  large  and  admirably  managed 
plants  elsewhere.  This  is  done  in  the  following  summary: 

TABLE  211. 
LABOR  AND  OUTPUT  IN  TYPICAL  PLANTS. 


Output 
per  Day. 

Process. 

Number 
of  Men. 

Barrels 
per  Man. 

Cost 
per  Barrel. 

1-00  bbls. 

Drv 

94 

12.78 

$0.1375 

2800     '  ' 

11 

159 

17.61 

.1216 

1GOO    " 

Wet 

142 

11.27 

.135 

It  is  to  be  noted  that  the  second  of  these  plants  uses  three  shifts  per 
day,  but  its  mechanical  equipment  is  so  perfect  that  this  does  not  show 
in 'the  labor  costs. 

Estimates  of  Total  Cost  per  Barrel. 

Disregarding  the  remarkably  low  estimates  of  cost  to  be  found  in 
prospectuses,  several  estimates  of  better  quality  have  been  published 
within  the  past  few  years.  These  relate  to  manufacture  carried  oh 
under  very  different  conditions,  two  applying  to  the  Lehigh  district, 
with  cheap  labor  and  fairly  cheap  fuel,  while  a  third  estimate  is  for  a 
plant  located  in  perhaps  the  worst  possible  spot  in  the  country  for  fuel, 
labor,  and  freight.  To  these  published  estimates  has  been  added  a 
table  prepared  by  the  present  writer. 

A  partial  account  *  of  costs  at  the  Atlas  plant  was  given  by  Messrs. 
St anger  and  Blount  a  few  years  ago.  This  is  as  follows: 

TABLE  212. 
COSTS  OF  CEMENT  MANUFACTURE  AT  ATLAS  PLANT. 


Cost  per  Ton, 
English  Money. 

Cost  per  Barrel. 

s.         d. 

1       95 

$0  076 

Fuel  for  power                  

3      0 

125 

Fuel  for  kiln                  

3      0 

125 

Labor                       

2      0 

082 

Repairs,  lubricants,  etc     

2     11* 

.124 

Superintendence  laboratory  and  mill  -office 

1       If 

048 

13     11 

.58 

The  following  estimate,  f  recently  published  by  Boilleau  and  Lyon, 
is  on  the  basis  of  a  2000-barrel  plant  (ten  60-foot  kilns)  located  in  the 
Lehigh  district. 

*  Proc.  Institution  Civil  Engineers,  vol.  145,  pp.  65-66.     1901. 
f  Municipal  Engineering,  vol.  26,  p.  394.     June,  1904. 


560  CEMENTS,  LIMES,  AND  PLASTERS. 

TABLE  213. 
DETAILED  ESTIMATES  OP  COSTS  OF  CEMENT  MANUFACTURE  (2000-BARREL  PLANT), 

Labor :  Cost  Per  Barrel. 

Quarry $0.05 

Stone  house 00? 

Mill  building 01$ 

Kiln-room ., 01$ 

Engine-  and  boiler-room /f 01$  [•  $0. 15 

Fuel  mill .' 01 

,  Yard  gang 01$ 

Repair  gang 02^ 

Miscellaneous OQ  J  . 

Raw  materials : 

Coal : 22$  \       24 

Gypsum Olf  J 

Supplies : 

Repair  parts 04    ") 

Lubricants 02    Y      .09 

Miscellaneous 03    J 

General  mill  account. 

Packing  and  shipping 04    1        Qg 


Office  force 02 

Fixed  charges: 

Interest  on  cost  of  plant 07 

Sinking  fund 05 

Depreciation 05 


.23$ 


Administration  and  selling  expenses 06$  J 

Total $0.77f 

Estimates  have  been  published  by  Mr.  E.  Duryee,  covering  the 
cost  of  building  a  small  plant  and  making  cement  at  a  very  inaccessible 
point  in  Arizona.  The  raw  materials  are  located  quite  near  the  plant, 
but  fuel,  labor,  and  freight  are  all  very  high.  These  estimates  are  as 
follows  : 

TABLE  214. 

APPROXIMATE  COST  OF  TWO-KILN  PLANT,  DAILY  CAPACITY  300  BARRELS. 

(DURYEE.) 

Crusher $2,000 

Mill  for  disintegrating  clay 500 

Rotaiy  clay  drier 1 ,500 

Elevators  and  conveyors  for  raw  materials 1 ,000 

Storage-bins  for  raw  materials 1 ,000 

Mills  for  grinding  raw  materials 10,000 

Two  rotary  kilns,  linings,  and  stacks 15,000 

Mills  for  grinding  cement 10,000 

300-H. P.  electric  motors  and  step-down  transformers.  9,000 

Conveyors  and  elevators  for  cement 1,500 

Cost  of  grading  and  erecting  machinery 10,000 

Shafting  and  pulleys,  belts,  and  setting  up 5,000 

Buildings  and  cement-bins 10,000 

Office,  laboratory,  and  laboratory  equipment 1,500 

Freight.  ... 10,000 

Plans,  specifications,  and  superintendence 3,000 

$91,000 


COSTS  AND   STATISTICS. 


561 


"With  such  a  mill,  and  using  charcoal  for  burning  cement,  the  cost 
of  manufacture  would  be  approximately  as  follows,  allowing  for  power 
only  the  proportion  necessary  for  maintaining  and  operating  the  electric 
plant  provided": 

Per  Barrel. 
Labor  and  superintendence $0 . 70 

Raw  materials 30 

Fuel  for  burning 90 

Power  (maintenance  and  operation  only) 05 

Repairs  and  sundries 05 

$2.00 
This  estimate  is  of  interest  in  connection  with  the  possible  erection 

of  plants  at  various  points  in  Spanish  America,  where  similar  conditions 

may  be  encountered. 

The   following   general    estimates   have   been   prepared    embodying 

the  data  presented  on  pages  554  to  559.     It  will  be  seen  that  they  apply, 

except  for  the  second  and  fifth  cases,  to  very  small  plants,  and  that  the 

totals  are  correspondingly  high. 

TABLE  215. 
ESTIMATES  OF  AVERAGE  COST  OF  PORTLAND-CEMENT  MANUFACTURE. 


Materials  •{ 

Lime-    •( 
stone     i 

Cement 
rock  and 

1  Marl  and 

Marl  and 

Marl  and 

Process 

and  clay  [ 
Dry 

limestone 
Dry 

clay 
Dry 

clay 
Wet 

clay 
Wet 

Number  of  kilns 

47 

S7 

4 

4 

8 

Size  of  kilns  
Output  per  day  .  . 

CO  feet 
700  bbls 

80  feet 
2000  bbls 

60  feet 
600  bbls 

60  feet 
400  bbls 

100  feet 
1100  bbK 

Cement  materials.  .  .  . 

0  08 

0  08 

0  03 

0  03 

0  03 

Power  coal  ]                 f 
Drier  coal     ^  at  $2.  .  \ 
Kiln  coal      J 
Labor 

0.08 
0.02 
0.12 
0  12 

0.08 
0.01 
0.10 
0  10 

0.09 
0.07 
0.14 
0  16 

0.13 
0.00 
0.20 
0  20 

0.11 
0.00 
0.15 
0  15 

Supplies,  etc  
Office  and  laboratory.  . 
Admin,  and  sales  
Interest,  etc  .  .  . 

0.15 
0.05 
0.08 
0  16 

0  Jll 
0.03 
0.05 
0  12 

0.15 
0.05 
0.10 
0  20 

0.16 
0.05 
0.13 
0  26 

0.12 
0.04 
0.09' 
0  20 

0.86 

0.68 

0.99 

1.16 

0.89 

Statistics  of  the  American  Portland-cement  Industry. 

Statistics  relative  to  the  growth  of  the  Portland-cement  industry 
in  the  United  States  will  be  found  serviceable  for  many  purposes,  and 
certain  data  on  this  point  have  been  accordingly  incorporated  in  the 
present  chapter. 

Total  production  and  growth  of  the  industry. — The  following  table 
has  been  prepared  to  illustrate  the  growth  of  the  American  Portland- 


562 


CEMENTS,  LIMES,  AND   PLASTERS. 


cement  industry,  from  its  inception  to  the  present  day,  in  regard  to 
number  of  plants,  annual  output,  and  value  of  product.  The  data 
used  in  compiling  this  table  are  taken  in  large  part  from  the  annual 
report  on  mineral  resources  issued  by  the  United  States  Geological 
Survey.  For  the  years  prior  to  1890  the  figures  are  to  be  regarded 
as  merely  rough  approximations  to  the,  truth,  but  in  later  years  they 
may  be  accepted  as  practically  correct. : 

TABJ.E  216. 
TOTAL  PRODUCTION  OF  PORTLAND  CEMENT  IN  THE  UNITED  STATES. 


Years. 

Barrels. 

Value. 

Plants. 

1870-1880.. 
1880   • 

82,000 
42,000 

$246,000 
126,000 

1881  

60,000 

150,000 

1882  

85,000 

191,250 

1883  

90,000 

193,500 

1884  

100,000 

210,000 

1885  

150,000 

292,500 

1886 

150,000 

292,500 

1887  
1888  .... 

250,000 
250,000 

487,500 
487,500 

1  889  

300,000 

500,000 

1890  

335,500 

704,050 

16 

1891  
1892  

454,813 
547,440 

967,429 
1,153,600 

17 
16 

1893 

590  652 

1,158,138 

19 

1894  
1895  
1896  .  .  . 

798,757 
990,324 
1,543,023 

1,383,473 
1,586,830 
2,424,011 

24 
22 
26 

1897  

2,677,775 

4,315,891 

29 

1898  

3,692,284 

5,970,773 

31 

1899  

5,652,266 

8,074,371 

36 

1900 

8  482  020 

9,280,525 

50 

1901 

12,711,225 

12,532,360 

56 

1902 

17,230,644 

20,864,078 

65 

1903  .... 

22,342,973 

27,713,319 

71 

1904  

26,505,881 

23,355,119 

75 

106,114,077 

$124,660,717 

Production  of  Portland  cement  by  States,  1901-1903.— In  the  table 
on  the  page  opposite,  which  is  slightly  revised  *  from  one  published 
by  L.  L.  Kimball  in  the  "  Mineral  Resources  of  the  U.  S.  for  1903",  the 
Portland-cement  production  of  the  separate  States  is  given  for  the 
years  1901,  1902,  and  1903. 

In  such  States  as  have  but  a  single  plant  their  production  is  com- 
bined with  that  of  another  State,  in  order  that  the  separate  figures  of 
any  plant  shall  not  be  revealed.  In  this  table  the  Portland-cement 

*  The  revision  is  the  correction,  in  the  third  column  from  the  right,  of  the 
number  of  plants  in  1903,  "which  in  the  original  was  evidently  incorrect. 


COSTS  AND  STATISTICS. 


563 


PRODUCTION  OF  PORTLAND  CEMENT  IN  THE  UNITED  STATES  IN  1901,  1902,  AND  1903,  BY  STATES. 

i 

i 

os"  co 
i-T 

i—  i  TF  00  l>  CD  ^  CO  C^  O                   O 
O^  CO  C^  CO  r—i  O^  ^^  Oi  C^                     CO 

27,713,319 

le  single  plants  in  Alabama  and  Georgia. 
"  "  "  Missouri  and  South  Dakota, 
plant  "  Utah, 
only  Portland-cement  plant  in  Kansas. 
"  Virginia, 
single  plant  in  South  Dakota. 

^^^(M^H 

(N  <N           1-H 

|| 

1-1  CO 
iO  1> 

coo 

COM 

O  !><M  CO  1>  r-i  CO  OS  CO                    1-1 
O  CO  00  00  "7)  00  "t1  I-H  i—  i                    CO 
IO  1-1  CO  i—  i  (M  CO  OS  »O  CO                   I-H 

ioi>i—  itociosoc^^o              co 

(M^O^O^OS^OO  cq^CD^t^  t^                  iO 
i-H  i-H  i—  1  i—  1         C^l  i—  1         OS 

22,342,973 

Number 
of 
Works. 

i—  i  i—  i  CO  I-H  i— 

•*  COi-H  COCN 

£ 

1 

•a 

oo 

i-H  r-H 

i—  i  iO 

coo 

Tfl  ,—  1 

OS  O  O_i-^ 

ilS§  §  1 

co"  I-H"  »o"  o"       TJH"       co" 
CO  (N  00  CO        CO        CO. 

ofi-T     o" 

oo 

o 
o" 

li 

OS  00 

1>  I>  O  O 

O  CO  CO  1> 

00  1s*  CO  ^t1    •     O        OS 

»O  O  I-H  »O        O        O 

i—  i  oo  I-H  rfi      10      oo 

C^l  O  CO  O        >o"       Tp" 
»O  iO  O  t>»        CO        CO 

•  <N"I-H"     oo" 

1 

T—  1 

Number 
of 
Works. 

^W^ftg^g^-^B, 

1 

I 

1 

co"co" 

00<N        O 
00  C^       (N_ 

i-To"     oo" 

1—  1 

OOO  r^  O       t^ 

lOi-H  IOOO        1-1 
TJ^CO  1>  CO        (N 

i-T         co" 

1 

i-H 

«*» 

"S 

1 

jj 

00  O 
00  O 

•O  C^        00 

(MO          r-( 

OS  rf        t>- 

§00  <N  O        <N 
C^  ^O  CO        *O 
(N  00  iO        !>• 

§ 

o  »o" 

00  00        *O 
(N  I-H        <N 

i—  I 

CS!  t>Tos"T-H         uf 

i—  1  1—  i  oo  os      os 

CO  O  CO  O         i-i 

5 

c 

Number 
of 
Works. 

i-H  i—  1  i-H 

^  (M  I-H  O 

10                           <D 

1 

1 

00 

3  1 

.••:.-••*  -£  •  -'c  s  •  :  :.s 

.    •  ,-'        •   *•*.•••*.  91  JA      8  ••E  -•••'••  S 

as  §.S  d   .   •   •   •  e.j  2  fe     >^    •   •    :E 
61  E^.sV£sl)S,£s2    ~.Q  :  :-S> 

53    C    O    S    fcJD'o    5    °3.-<    0^^            02    r-i    02       •    C 

564 


CEMENTS,  LIMES,  AND   PLASTERS. 


product  in  1903  of  the  only  plant  in  Alabama  which  produces  that 
variety  of  cement  is  combined  with  the  product  of  the  plants  in 
Georgia,  Virginia,  and  West  Virginia.  The  plants  in  Missouri  and 
Arkansas  have  their  products  combined;  those  in  Kansas  and  Texas, 
.•and  those  in  Utah,  South  Dakota,  and  Colorado  also  show  combined 
products,  and  in  each  case  the  result^ is  given  in  connection  with  the 
State  which  was  the  largest  contributor  to  the  total  product. 

Production  in  the  Lehigh  district,  1890-1903. — The  following  table 
has  been  prepared  by  the  writer  to  illustrate  the  position  held  by  the 
Lehigh  district  of  Pennsylvania-New  Jersey: 

TABLE  218. 
PORTLAND-CEMENT  PRODUCTION  OF  THE  LEHIGH  DISTRICT,  1890-1903. 


"Year.       \ 

Lehigh  District. 

Entire  United  States. 

Percentage  of 
Total  Product 
Manufactured 
in  Lehigh 
District. 

Number 
of  Plants. 

Number'  of 
Barrels. 

Number 
of  Plants. 

Number  of 
Barrels. 

Value. 

1890  .  . 
1891  
1892  
1893.  
1894   .... 

5 
5 
5 
5 

7 
8 
8 
8 
9 
11 
15 
16 
17 
17 

201,000 
248,500 
280,840 
265,317 
485,329 
634,276 
1,048,154 
2,002,059 
2,674,304 
4,110,132 
6,153,629 
8,595,340 
10,829,922 
12,324,922 

16 
17 
16 
19 
24 
22 
26 
29 
31 
36 
50 
56 
65 
71 

335,500 
454,813 
547,440 
590,652 
798,757 
990,324 
1,543,023 
2,677,775 
3,692,284 
5,652,266 
8,482,020 
12,711,225 
17,230,644 
22,342,973 

$439,050 
1,067,429 
1,152,600 
1,158,138 
1,383,473 
1,586,830 
2,424,011 
4,315,891 
5,970,773 
8,074,371 
9,280,525 
12,532,360 
20,864,078 
27,713,319 

60.0 
54.7 
51.3 
44.9 
60.8 
64.0 
68.1 
74.8 
72.4 
72.7 
72.6 
67.7 
62.8 
55.1 

1895  
1893  
1897  
1898...... 
1899  
1900 

1901  
1902  
1903  

Imports   of  cement,   1899-1903. — The  imports  of  cement  into  the 
United  States  in  1899  to  1903  inclusive,  by  countries,  were  as  follows: 

TABLE  219. 

IMPORTS  OF  HYDRAULIC  CEMENT  INTO  THE  UNITED  STATES  IN  1899,  1900,  1901, 
1092,   AND    1903,   BY  COUNTRIES. 


Country. 

1899. 

1900. 

1901. 

1902. 

1903. 

United  Kingdom  

Barrels. 
199,633 

Barrels. 
267,921 

Barrels. 
37,390 

Barrels. 

79,087 

Barrels. 
146,994 

Belgium  

624,149 

826,289 

303,180 

615,793 

737,576 

Trance 

15,649 

32,710 

11,771 

14,922 

14,865 

'Germany      .        .    . 

1,193,822 

1,155,550 

555,038 

1,259,265 

1,377,414 

Other  European  coun- 
tries   
British  North  America.  . 
Other  countries  

68,348 
4,398 
2,389 

75,827 
4,517 
23,869 

19,077 
6,066 
6,808 

17,956 
3,611 
4,153 

27,415 
4,421 
9,265 

Total  

2,108,388 

2,386,683 

939,330 

1,994,787 

2,317,950 

COSTS  AND  STATISTICS.  565 

"The  figures  used  in  compiling  this  table  are  those  which  show  the 
total  imports.  In  1903  England  stands  third  in  the  list  of  foreign  coun- 
tries which  sent  cement  to  America.  From  1871  to  1876  nearly  all 
importations  of  foreign  cement  were  from  England.  In  the  four  years 
following  Germany  gradually  assumed  an  important  place  as  rival, 
and  in  1882,  while  England  sent  one  half  the  cement  exported  to  the 
United  States,  Germany  sent  three  fourths  of  the  remainder.  Ten 
years  later  Germany  was  the  leading  foreign  country  sending  cement 
to  America,  and  since  theii  has  held  that  position/' 


CHAPTER  XXXVIII. 

CONSTITUTION,  SETTING  PROPERTIES,  AND  COMPOSITION  OF 
PORTLAND  CEMENT. 

Limitations  of  chemical  analyses. — An  ordinary  chemical  analysis 
of  a  specimen  of  cement  will  determine  what  elements  are  present  in 
the  cement,  and  in  what  percentages  these  various  constituents  are 
represented.  The  comparison  of  a  long  series  of  such  analyses,  such  as 
is  presented  later  in  this  chapter,  will  enable  certain  conclusions  to  be 
drawn  as  to  the  probable  limits  of  composition  of  good  Portland  cements; 
and  an  analysis  of  a  single  cement  may  show  that  it  contains  undesirable 
ingredients  or  that  inert  material  is  present  in  undesirable  quantity. 
But  these  methods  of  investigation  fail  to  give  the  least  information 
concerning  the  real  constitution  of  Portland  cement  as  distinguished 
from  its  composition;  they  give  no  information  whatever  as  to  the  man- 
ner in  which  the  various  elements  are  combined  among  themselves. 
They  fail,  moreover,  to  give  any  clue  to  the  reason  why  certain  mixtures 
give  good  cements,  while  others  give  weak  or  unsound  products;  and 
they  afford  no  explanation  of  the  "hydraulic"  or  setting  properties 
which  the  powdered  clinker  possesses.  It  is  evident,  therefore,  that 
other  methods  of  investigation  must  be  adopted,  since  even  the  most 
careful  chemical  analysis  fails  to  aid  us  in  this  line  of  research. 

Constitution  and  Setting  Properties. 

Available  methods  of  investigation. — Two  distinct  methods  of  in- 
vestigation are  available — microscopic  and  synthetic. 

The  first  has  been  applied  with  great  success  by  geologists  to  the 
study  of  the  igneous  rocks,  and  as  cement  clinker  is  practically  an  arti- 
ficial (though  very  basic)  igneous  rock,  the  microscope  can  be  used 
successfully  in  its  examination.  By  grinding  normal  clinker  of  known 
analysis  down  to  thin  transparent  slices,  the  microscope  is  able  to  detect 
certain  constituents  common  to  all  good  clinkers.  The  next  step, 
of  course,  is  to  determine  the  composition  of  these  different  constitu- 
ents, and  here  the  synthetic  method  is  applicable. 

566 


CONSTITUTION,  ETC.,  OF  PORTLAND  CEMENT.  567 

In  synthetic  work  pure  lime,  silica,  alumina,  etc.,  are  mixed  in  certain 
definite  proportions  and  burned  to  a  clinker.  The  hydraulic  properties 
of  this  clinker  can  be  examined  by  powdering  part  of  it  and  testing 
the  resulting  cement.  Examination  under  the  microscope  will  fix 
certain  optical  characters  peculiar  to  each  clinker  composition,  and 
the  data  thus  obtained  can  be  used  to  determine  the  constituents  of 
commercial-cement  clinker,  as  noted  in  the  preceding  paragraph. 

Synthetic  investigations. — Richardson  has  recently  summarized  the 
results  of  his  own  studies  and  those  of  previous  observers  as  follows : 

"The  preparation  of  synthetic  silicates  and  aluminates  which  might 
exist  in  Portland  cement  was  carried  out  to  a  certain  extent  by  Le  Cha- 
telier  and  the  Newberrys,  but  in  neither  case  were  these  compounds 
characterized  completely,  especially  as  to  their  optical  properties.  This 
has  been  done  by  the  writer  within  the  last  two  years,  and  the  optical 
properties  and  other  characteristics  of  the  following  definite  silicates 
and  aluminates  have  been  determined. 

"  Monocalcic  silicate  (Si02CaO) :  A  crystalline  substance  of  high 
optical  activity  and  little  or  no  hydraulic  properties.  Specific  gravity 
2.90. 

"Dicalcic  silicate  (SiO22CaO,  or  more  probably  2SiO24CaO):  A 
definite  crystalline  compound  of  high  optical  activity  and  of  very  little 
hydraulic  activity  except  in  the  presence  of  carbonic  acid,  but  setting 
slowly  in  water,  generally  lacking  volume  constancy.  Specific  gravity 
3.29. 

"Tricalcic  silicate  (Si023CaO) :  A  definite  crystalline  silicate  of 
low  optical  activity  and  corresponding  in  this  respect  with  alit.  Its  hy- 
draulic activity  is  not  great,  but  greater  than  that  of  dicalcic  silicate. 
If  fused  and  reground  it  sets  slowly  like  Portland  cement.  Specific 
gravity  3.03. 

"Three  definite  silicates  of  calcium,  therefore,  appear  to  exist,  the 
two  more  basic  ones  being  strongly  differentiated  from  each  other  by 
their  optical  activity. 

"Monocalcic  aluminate  (A^OaCaO):  This  aluminate  is  a  crystal- 
line substance  of  high  optical  activity,  but  is  not  sufficiently  basic  to 
permit  of  its  existence  in  a  material  of  such  basic  character  as  Portland- 
cement  clinker.  Specific  gravity  2.90. 

"Tricalcic  dialuminate  (2Al2033CaO) :  This  aluminate  is  one  of 
highly  crystalline  character  and  of  great  optical  activity,  making  it 
readily  recognizable.  Specific  gravity  2.92. 

"Dicalcic  aluminate  (Al2O32CaO):  A  substance  crystallizing  from  a 
state  of  fusion  in  dendritic  forms  having  no  optical  activity  and  being, 


568  CEMENTS,  LIMES,  AND   PLASTERS. 

therefore,  iso  tropic.  This  differentiates  this  alumina te  very  sharply 
from  the  preceding  one  and  makes  the  identification  of  the  two  materials 
very  easy.  Specific  gravity  2.79. 

"Tricalcic  alumina  te  (A^OaSCaO):  This  aluminate  crystallizes  from 
the  fused  condition  in  elongated  octahedra.  It  is  isotropic  and  it  might 
at  first  be  assumed  that  it  was  not  a  definite  compound,  but  merely  the 
dicalcic  aluminate  crystallizing  out  of  a  magma  of  indefinite  composi- 
tion. It  has  been  shown,  however,  by  further  investigations  too  lengthy 
to  go  into  at  this  point,  to  be  undoubtedly  a  definite  aluminate.  Specific 
gravity  2.91. 

"Definite  compounds  of  iron  and  lime  and  alumina  and  magnesia 
have  also  been  shown  to  exist,  but  their  consideration  here  is  unneces- 
sary, as  the  constitution  of  Portland  cement  can  be  better  discussed, 
theoretically,  by  a  study  of  clinker,  into  which  these  elements  do  not 
enter. 

"Among  the  theories  advanced  as  to  the  constitution  of  Portland 
cement  there  are  those  which  assume  the  presence  of  certain  so-called 
silico  aluminates,  such  as  2Si02,  2Al2Os,  GCaO,  and  others  of  less  basic 
form.  All  of  these  proposed  compounds  have  been  prepared  by  the 
writer  and  found  not  to  be  definite  chemical  compounds  nor  to  corre- 
spond in  any  way  with  any  of  the  mineral  entities  found  in  industrial 
clinker.  They  are  in  fact  only  solid  solutions,  of  aluminates  in  silicates, 
of  indefinite  structure." 

Microscopic  investigations. — Le  Chatelier,  Tornebohm,  and  Richard- 
son have  studied  both  industrial  and  synthetic  clinker  under  the  micro- 
scope, and  the  results  of  these  preliminary  studies  have  thus  been  sum- 
marized by  the  last-named  investigator: 

"By  this  method  of  study  Le  Chatelier,  and,  at  the  same  time  inde- 
pendently of  him,  Tornebohm  identified  in  Portland-cement  clinker 
four  distinct  mineral  constituents  which  Tornebohm  described  as  fol- 
lows, naming  them  Alit,  Belit,  Celit,  and  Felit: 

"Alit  is  the  preponderating  element  and  consists  of  colorless  crys- 
tals of  rather  strong  refractive  power,  but  of  weak  double  refraction. 
By  this  he  means  that  alit  in  polarized  light  between  crossed  nicol  prisms 
has  insufficient  optical  activity  to  produce  more  than  weak  bluish  gray 
interference  colors. 

"  Celit  is  recognized  by  its  deep  color,  brownish  orange.  It  fills  the 
interstices  between  the  other  constituents,  being  the  magma  or  liquid 
of  lowest  freezing-point  out  of  which  the  alit  is  separated.  It  is  strongly 
double  refractive,  that  is  to  say,  gives  brilliant  colors  when  examined 
between  crossed  nicol  prisms. 


CONSTITUTION,  ETC.,  OF  PORTLAND  CEMENT.  569 

"  Belit  is  recognized  by  its  dirty  green  and  somewhat  muddy  color 
and  by  its  brilliant  interference  colors.  It  is  biaxial  and  of  high  index 
of  refraction.  It  forms  small  round  grains  of  no  recognized  crystalline 
character. 

"  Felit  is  colorless.  Its  index  of  refraction  is  nearly  the  same  as  that 
of  beiit  and  it  is  strongly  double  refractive.  It  occurs  in  the  form  of 
round  grains,  often  in  elongated  form,  but  without  crystalline  outline. 
Felit  may  be  entirely  wanting. 

"  Besides  these  minerals  an  amorphous  isotropic  mass  was  detected 
by  Tornebohm  and  Le  Chatelier.  It  has  a  very  high  refractive  index. 

"  Tornebohm  adds  ttoe  important  fact  that  a  cement  4  per  cent  richer 
in  lime  than  usual  consists  almost  entirely  of  alit  and  celit." 

Theories  of  constitution. — Until  recently  Portland-cement  clinker 
was  commonly  assumed  to  be  a  mixture  of  two  or  more  definite  chemi- 
cal compounds,  and  the  principal  points  at  issue  between  various  inves- 
tigators were:  (1)  the  exact  formulas  for  these  compounds,  and  (2)  the 
proportion  in  which  they  must  exist  to  give  a  good  Portland  cement. 
The  two  theories,  in  this  regard,  that  have  made  the  most  impression 
upon  modern  cement  practice  are  those  presented  respectively  by  Le 
Chatelier  and  Newberry.  Recently,  however,  Richardson  has  formu- 
lated a  theory  of  entirely  different  type.  These  three  explanations  of 
the  constitution  of  Portland  clinker  will,  therefore,  be  described  briefly. 

Le  Chatelier,  speaking   of   Portland-cement  clinkers,  states  *  that;: 

"  Examined  in  thin  plates  under  the  microscope  they  are  formed 
of  tricalcie  silicate  in  crystals,  with  very  feeble  double  refraction, 
embedded  in  a  crystalline  ground-mass  of  silico-alumina — ferrites  of 
lime.  These  are  the  two  essential  elements  of  Portland  cement.  If 
the  lime  is  in  excess,  aluminate  of  lime  is  first  formed;  then  for  a  still 
greater  excess,  ferrite  of  lime,  and  finally  free  lime.  If,  on  the  other 
hand,  the  lime  is  deficient  in  quantity,  a  dicalcic  silicate  is  formed, 
recognizable  by  the  spontaneous  crumbling  of  the  burnt  pieces  of  cement. 
When  the  mixture  is  imperfect  or  the  burning  insufficient,  the  reactions 
jemain  incomplete,  and  although  the  average  composition  may  be 
suitable,  there  is  a  simultaneous  production  of  free  lime  and  aluminate 
of  calcium  with  dicalcic  silicate.  In  a  Portland  cement  of  normal  com- 
position the  proportion  of  lime,  according  to  the  chemical  formulas 
of  the  compound,  should  be  greater  than  that  determined  by  the  follow- 
ing formula: 

Si02-Al203-Fe203^0 

Cao >3' W 

*  Trans,  Anier.  Inst.  Mining  Engineers,  vol.  22,  pp.  3-52. 


570  CEMENTS,  LIMES,  AND  PLASTERS. 

in  which  CaO,  Si02,  A12O3,  Fe2O3  represent  not  the  equivalent  weights 
but  the  number  of  equivalents  of  these  substances  present;  that  is  to 
say,  the  quotients  of  the  weights  of  the  substances  divided  by  their 
equivalent  weights.*  This  proportion  of  lime  must  never,  on  the  other 
hand,  reach  the  relation  indicated  by  the  following  formula: 


(2) 


which  corresponds  to  the  exclusive  formation  of  aluminate  of  calcium. 
It  is  necessary,  by  reason  of  the  inevitable  imperfection  of  the  mix- 
ture, to  keep  always  well  below  this  limit,  beyond  which  there  will 
remain  uncombined  lime.  In  the  use  of  this  formula,  magnesia  should 
be  added  to  the  lime  and  sulphuric  acid  to  the  denominator  after  dividing 
its  number  of  equivalents  by  3." 

On  a  later  page  Le  Chatelier  states  that  Portland  cements  of  good 
quality  would  give  a  value  between  3.5  and  4.0  for  formula  1,  and 
between  2.5  and  2.7  for  formula  2. 

The  Newberrys,  working  on  synthetic  cements  prepared  from  pure 
raw  materials,  obtained  results  differing  from  those  of  Le  Chatelier  in 
one  important  particular.  They  agreed  with  him  that  the  lime  and 
silica  combined  in  the  form  of  the  tricalcic  silicate  3CaO.Si02;  but  in 
regard  to  the  lime-alumina  compound  they  decided  that  it  was  present 
as  the  dicalcic  aluminate  2CaO.Al2Os  instead  of  in  the  tricalcic  form 
given  by  Le  Chatelier.  These  results  gave,  as  the  general  formula  for 
a  pure  Portland, 

*(3CaO.SiO2)  +2/(2CaO.Al203). 

No  allowance  is  made  for  magnesia,  as  the  experimenters  decided 
that  it  could  not  give  a  hydraulic  product  if  present  in  Portland  cement; 
while  iron  is  neglected  because  of  the  small  percentage  in  which  it  usu- 
ally occurs. 

Richardson,  working  both  with  the  microscope  and  with  synthetic 
preparations,  has  evolved  a  theory  of  much  ingenuity  and  complexity 
by  treating  the  investigation  as  a  study  in  solid  solutions.  For  the 
details  of  this  remarkable  and  important  work  reference  should  be 
made  to  his  original  papers. t  In  the  present  place  only  a  brief  sum- 
mary of  his  principal  conclusions  can  be  given. 

He  believes  that  the  two  principal  constituents  of  a  good  Portland- 

*  For  a  table  of  combining  weights,  see  p.  11  of  this  volume, 
t  See  list  on  p.  575. 


CONSTITUTION,  ETC.,  OF  PORTLAND  CEMENT.  571 

cement  clinker  are  the  materials  identified  under  the  microscope  by 
Tornebohm  and  named  alit  and  celit;  that  alit  is  a  solid  solution 
of  tricalcic  aluminate  (SCaO.A^Os)  in  tricalcic  silicate  (CaO.Si02), 
while  celit  is  a  solid  solution  of  dicalcic  aluminate  pCaO.A^Os)  in 
dicalcic  silicate  (2CaO.SiO2). 

"Having  determined  that  alit  and  celit  are  solid  solutions  of  alu- 
minates  in  silicates,  the  aluminates  being  present  in  less  than  an  amount 
sufficient  to  make  a  saturated  solution  of  aluminate  in  the  silicate, 
it  becomes  of  interest  to  consider  how  these  solutions  are  formed  during 
the  conversion  of  a  raw  mixture  or  of  a  mixture  of  pure  chemicals  into 
a  clinker.  It  would  be  simple  to  understand  this  if  fusion  took  place  in 
its  formation,  but  this  does  not  happen,  the  material  is  only  sintered. 
If  two  gases  are  brought  together  they  diffuse  into  each  other  with  very 
great  rapidity.  If  two  liquids  are  poured  one  upon  the  other  in  layers 
without  mixing,  they  diffuse  more  slowly.  If  solids  are  brought  into 
contact  it  would  be  naturally  assumed  that  diffusion  would  cease.  Experi- 
ments of  Robert-Austen  have  shown  that  molecular  mobility  in  solids 
exists,  since  when  carefully  polished  surfaces  of  gold  and  lead  are  brought 
into  contact  and  left  under  pressure  for  some  months,  at  the  ordinary 
temperatures,  gold  is  diffused  into  the  lead  and  the  lead  into  the  gold 
for  an  appreciable  distance.  Mixtures  of  the  components  which  would 
produce  a  fusible  wood  metal  when  subjected  to  pressure  at  ordinary 
temperature  become  converted  into  this  alloy.  Anhydrous  sulphate 
of  soda  and  carbonate  of  barium  also  diffuse  when  brought  into  close 
contact  with  the  formation  of  barium  sulphate  and  carbonate  of  soda. 
It  is  not  difficult  to  understand,  therefore,  how  at  a  temperature  of 
1650°  C.  the  particles  of  silica,  alumina,  and  lime  may  diffuse  below 
the  melting-point  of  the  resulting  clinker  to  form  a  Portland  cement, 
and  the  fact  that  such  a  clinker  is  stable  depends  not  only  on  its  com- 
position, but  upon  the  fact  that  the  diffusion  has  been  complete,  even 
in  material  which  is  only  sintered.  Sintering,  therefore,  may  be  defined 
as  diffusion  at  a  temperature  below  the  melting-point  of  the  compo- 
nents or  of  the  resulting  solid  solution.  That  diffusion  under  such  con- 
ditions is  surprisingly  rapid  is  seen  by  placing  a  particle  of  ferric  oxide 
on  the  surface  of  white  Portland-cement  clinker,  and  then  submitting 
it  to  a  moderately  high  temperature.  The  rapid  diffusion  of  iron  through 
the  white  clinker  can  readily  be  noticed  by  the  color  which  spreads 
through  the  mass.  It  is  evident  that  the  higher  the  temperature  the 
more  rapid  the  diffusion  until  it  becomes  very  rapid  on  fusion.  From 
this  it  may  be  concluded  that  the  length  of  time  during  which  it  is 
necessary  to  expose  any  mixture  of  silica  alumina  and  lime  to  a  tern- 


572  CEMENTS,  LIMES,  AND  PLASTERS. 

perature  is  a  function  of  the  temperature,  and  should  be  longer,  the 
lower  the  temperature." 

Setting  properties  of  Portland  cement. — The  theory  which  has  been 
quite  generally  accepted  as  explaining  the  setting  of  Portland  cement 
was  that  advanced  by  Le  Chatelier.  He  considered  that  the  aluminate 
of  lime,  in  contact  with  water,  hydjated  and  hardened  like  plaster, 
according  to  the  equation: 

3CaO.  A12O3  +  12H2O  =  3CaO.  A12O3. 12H20. 

i. 

To  this  action  of  the  aluminate  was  ascribed  the  initial  set  of  the  cement. 
The  later  hardening  was  ascribed,  however,  to  the  decomposition  of  the 
lime  silicate.  In  contact  with  water  it  sets,  dividing  so  as  to  give 
hydrated  monocalcic  silicate  crystallizing  in  microscopic  needles,  and 
calcium  hydrate  crystallizing  in  large  hexagonal  plates : 

3CaO.SiO2  +  water  =  CaO.SiO2.2JH20 + 2(CaO.H2O) . 

In  general  this  theory,  has  been  accepted. 

Richardson,  however,  has  recently  modified*  this  theory  in  an  im- 
portant way.  He  considers  that  the  setting  of  Portland  cement  is 
due  to  the  decomposition  of  the  silicates  and  aluminates  of  the  clinker 
by  the  action  of  water,  producing  lime  hydrate  (Ca2H202)  in  a  peculiarly 
active  form. 

"On  the  addition  of  water  to  a  stable  system  made  up  of  the  solid 
solutions  which  composed  Portland  cement  a  new  component  is  intro- 
duced which  immediately  results  in  a  lack  of  equilibrium,  which  is  only 
brought  about  again  by  the  liberation  of  free  lime.  This  free  lime  the 
moment  that  it  is  liberated  is  in  solution  in  the  water,  but  owing  to  the 
rapidity  with  which  it  is  liberated  from  the  aluminate,  the  water  soon 
becomes  supersaturated  with  calcic  hydrate,  and  the  latter  crystallizes 
out  in  a  network  of  crystals  which  binds  the  particles  of  undecomposed 
Portland  cement  together.  From  the  characteristics  of  the  silicates 
and  aluminates  it  is  evident  that  the  latter  are  acted  upon  much  more 
rapidly  than  the  silicates,  and  it  is  to  the  crystallization  of  the  lime 
from  the  aluminates  that  the  first  or  initial  set  must  be  attributed. 
Subsequent  hardening  is  due  to  the  slower  liberation  of  lime  from  the 
silicates.  If  the  lime  is  liberated  more  rapidly  than  is  possible  for  it  to 
crystallize  out  from  the  water,  expansion  ensues  and  the  cement  is 
not  volume  constant." 

*  Richardson  C.  The  setting  or  hydration  of  Portland  cement.  Engineering 
News,  vol.  53,  pp.  84-85.  Jan.  26,  1905. 


CONSTITUTION,  ETC.,  OF  PORTLAND  CEMENT.  57$ 

He  further  notes  that  of  the  two  constituents  of  the  clinker  the  celit. 
is  almost  inert,  being  usually  unattacked  by  the  water,  while  the  alit 
furnishes  most  of  the  lime  needed  for  the  setting  effect.  As  the  celit 
is  a  solution  of  dicalcic  salts  (2CaO.SiO2  +  2CaO.Al203),  while  the  alit  is  a 
solution  of  tricalcic  compounds  (3CaO.Si02  +  3CaO.Al2O3),  the  lower- 
limed  cements  are,  therefore,  the  less  hydraulic.  This  agrees  with 
experience. 

This  theory  differs  from  Le  Chatelier's  in  that  it  considers  setting 
as  due  only  indirectly  to  the  presence  of  silicates  and  aluminates. 

"The  strength  of  the  Portland  cement  after  setting  is  due  entirely  to 
the  crystallization  of  calcium  hydrate  under  certain  favorable  conditions, 
and  not  at  all  to  the  hydration  of  the  silicates  or  the  aluminates,  since 
in  this  act  of  hydration  nothing  can  take  place  which  would  tend  to 
bind  these  silicates  and  aluminates  together." 

The  formation  of  lime  silicates  and  aluminates  during  clinkering 
is  on  this  theory  only  a  convenient  way  of  securing  indirectly  a  very 
active  lime  hydrate,  which  is  itself  the  real  cementing  material. 

Replacement  of  silica  by  other  acids. — Various  oxides  of  the  silica 
group  have  been  substituted  by  Richardson  in  his  series  of  synthetic 
cements.  Titanic  oxide  (TiO2),  stannic  oxide  (SnO2),  and  plumbic 
oxide  (PbO)  have  been  so  used.  "The  ground  clinker  in  each  case 
has  been  found  to  set  rapidly,  although  the  resulting  test  pieces  were 
not  volume  constant,  the  temperature  obtainable  in  our  furnace  being 
evidently  insufficient  to  bring  about  a  thorough  combination  between 
these  oxides  and  lime.  Cements  have  been  made  in  which  phosphoric 
acid  (P20s)  has  been  substituted  for  silica." 

Replacement  of  alumina  by  iron  oxide. — Some  difference  of  opinion 
appears  concerning  the  extent  to  which  the  alumina  of  a  Portland  ce- 
ment may  be  replaced  by  iron  oxide. 

This  problem  was  taken  up  by  the  Newberrys  in  the  classic  researches 
before  cited.  They  prepared  mixtures  of  pure  iron  oxide  and  calcium 
carbonate  in  such  proportions  as  to  correspond  to  the  formula  2CaO.- 
Fe203,  which  in  percentages  is  equivalent  to  CaO  41.3  per  cent,  Fe20s 
58.7  per  cent.  "On  burning,  the  material  fused  to  a  black  slag,  which 
yielded  a  brown  color  on  grinding.  Mixed  with  water  to  a  paste,  this 
powder  showed  no  heating,  and  did  not  set  or  harden  in  air  or  cold  water. 
A  part  placed  in  steam  however,  after  setting  one  day  in  air,  hardened 
rapidly,  and  after  several  hours  in  boiling  water  showed  no  cracking 
and  appeared  very  hard.  From  this  experiment  it  appears  that  lime 
and  iron  oxide  readily  combine,  yielding  a  product  which  is  constant 
in  volume,  though  it  shows  no  hardening  properties  in  the  cold."  The 


574  CEMENTS,  LIMES,  AND  PLASTERS. 

Newberrys  cany  the  experiments  further,  making  a  silica-,  iron  oxide, 
lime  mixture  entirely  free  from  alumina.  This  was  made  to  correspond 
to  the  formula 

(3CaO.Si02)  +  X  (2CaO.Fe203), 

and  contained  about  7  per  .cent  of  Jron  oxide.  On  burning  this  gave 
a  black,  fusible  clinker.  When  powdered  this  was  dark-gray,  and 
gave  a  slow-setting  hard  and  sound  cement. 

Their  final  conclusions  were,  that  though  "iron  oxide  evidently 
combines  with  lime  in  the  same  manner  as  alumina,"  the  amount  of 
iron  oxide  present  in  ordinary  clays  is  so  small  that  "it  is  quite  unneces- 
sary, in  working  with  ordinary  clays,  to  take  the  iron  oxide  into  con- 
sideration in  calculating  the  amount  of  lime  required." 

In  view  of  the  manufacture  of  cements  containing  appreciable  per- 
centages of  iron  oxide,  it  seems  advisable  to  take  this  constituent  into 
consideration  in  proportioning  mixes,  and  this  has  accordingly  been 
done  in  the  formula  given  earlier  in  this  volume. 

Replacement  of  lime  by  magnesia. — The  possibility  of  this  replace- 
ment has  been  flatly  denied  by  some  of  our  leading  authorities  on  cement 
chemistry,  while  it  has  been  maintained,  but  less  confidently,  by  others. 
To  the  present  writer  it  seems  certain  that  magnesia  is  absolutely  in- 
terchangeable with  lime,-  due  regard  being  paid  to  their  differences 
in  atomic  weight.  It  is  only  necessary  to  adduce  the  example  of  the 
high-burned  natural  cements,  such  as  the  Akron,  to  make  it  clear  that 
a  cement  containing  15  to  20  per  cent  of  magnesia  can  be  made  at  almost 
clinkering  temperature.  Recent  experiments  by  Newberry  seem  to  con- 
firm this  conclusion.  It  is  to  be  noted,  however,  that  a  Portland  cement 
carrying  high  percentages  of  magnesia  will  necessarily  differ  considera- 
bly from  our  present-day  lime  Portlands.  It  is  even  probable  that 
the  differences  in  physical  and  technical  properties  will  be  so  great  that 
it  will  be  necessary  to  market  such  magnesia  Portlands  under  some  dis- 
tinct trade-name. 

Replacement  of  lime  by  other  bases. — Magnesia  is  not  the  only 
base  that  can  replace,  either  partly  or  entirely,  the  lime  of  a  normal 
Portland-cement  clinker.  Other  alkaline  earths  can  be  so  substituted, 
as  was  proven  in  the  course  of  Richardson's  recent  experiments.  He 
describes  *  this  phase  of  his  work  as  follows: 

"Clinkers  have  been  made  in  which  baryta  (BaO)  and  strontia 
(SrO)  are  the  bases.  They  must  be  burned  at  a  very  much  higher 
temperature  than  similar  clinkers  containing  lime.  In  powder  these 

*  Engineering  News,  vol.  53,  p.  85.     Jan.  26,  1905. 


CONSTITUTION,  ETC.,  OF  PORTLAND  CEMENT. 


575 


(barium  and  strontium  cements)  possess  strong  hydraulic  properties, 
and  are  volume  constant  in  water  for  a  few  days,  but  owing  to  the 
greater  solubility  in  water  of  barium  and  strontium  hydrate  than  of 
lime  hydrate,  the  material  after  setting  is  much  more  readily  attacked 
by  water  than  is  lime  cement,  strontium  hydrate  being  about  twice 
as  soluble  as  calcium  hydrate,  and  barium  hydrate  about  eight  times  as 
soluble." 

References  on  the  constitution  of  Portland  cement. — The  following 
brief  list  will  serve  as  an  introduction  to  the  mass  of  literature  on  this 
subject: 
Bonnami,  H.     Fabrication  et  contiole  des  chaux  hydrauliques  et  des  ciments. 

8vo,  276  pp.     Paris,  1888. 
Le  Chatelier,  H.     Tests  of  hydraulic  materials.     Trans.  Amer.  Inst.  Mining 

Engineers,  vol.  22,  pp.  3-52.     1894. 
Newberry,  S.  B.  and  W.  B.     The  constitution  of  hydraulic  cements.     Journ. 

Soc.  Chem  Industry,  vol.  16,  pp.  887-894.     1897 
Richardson,  C.     The  constitution  of  Portland  cement.     Cement,  vols.  3,  4,  5. 

1903-1905 
Richardson,  C.     The  constitution  of  Portland  cement  from  a  physico-chemical 

standpoint.     12mo,  20  pp.     Long  Island  City,  N.  Y.,  1904. 
Richardson,  C.     The  setting  or  hydration  of  Portland  cement.     Engineering 

News,  vol.  53,  pp.  84-85.     Jan.  26,  1905. 

Composition  of  Portland  cements. — The  chemical  composition  of  Port- 
land cements  has  been  changing  slowly  in  one  direction  since  1850.  This 
is  well  brought  out  by  the  analyses  of  old  Portland  cements  given  in 
the  following  table,  when  compared  with  the  analyses  of  modern  Port- 
lands given  in  Table  221. 

TABLE  220. 
ANALYSES  OF  PORTLAND  CEMENT,  1849-1873. 


1. 

2. 

3. 

4. 

Silica  (SiO0)           

18  60 

22  23 

23  72 

18  60 

11.30 

7  75 

7  36 

4  75 

Iron  oxide  (Fe2O3)   

17.90 

5  30 

5  05 

5  60 

Lime  (CaO)       

49.80 

54  11 

54  40 

58  50 

0.70 

0.75 

0  86 

2  55 

Alkalies  (K2O,Na2O)  

n.  d. 

1.76 

2.62 

1  70 

Sulphur  trioxide  (SO3)  

n.  d. 

1.00 

1   12 

2  10 

Carbon  dioxide  (CO2) 

n  d 

2  15 

2  80 

0  50 

Water 

n  d 

1  00 

0  96 

0  50 

1.  Manufactured  about   1873   by  I.   C.  Johnson  &  Co.,   England.     Reports  Vienna  Exposition, 

vol.  4,  pt.  D,  p.  35. 

2.  Manufactured   about    1849  in   England.     Analyzed  by  Pettenkofer.      Proc.   Institution   Civil 

Engineers,  vol.  62,  p.  77. 

3.  Manufactured  about  1873  in  England.     Analyzed  by  Feichtinger.      Reports  Vienna  Exposition, 

vol.  4,  pt.  D,  p.  37. 

4.  Manufactured  about   1873  in  Austria.     Analyzed  by  Wagner.      Reports  Vienna  Exposition, 

vol.  4,  pt.  D,  p.  37. 


576  CEMENTS,  LIMES,  AND  PLASTERS. 

From  inspection  of  the  above  table  it  will  be  seen  that  old  Portlands 
were  very  low-limed  products.  Some,  in  fact,  were  too  low  in  lime  to 
be  considered,  at  the  present  day,  as  falling  in  the  Portland  class. 

Composition  of  American  Portland  cements. — Table  221,  contain 
ing  a  large  series  of  analyses  of  American  Portland  cements,  has  been 
compiled  by  the  writer  from  various,  sources.  About  half  of  the 
analyses  contained  in  it  .  have  already  been  published  in  different 
books  and  periodicals,  while  for  the  remainder  the  writer  is  indebted 
to  the  chemists  of  the  various  plants. 

Standard  Methods  of  Analysis. 

The  following  methods  of  analysis  are  those  suggested  by  a  com- 
mittee of  the  New  York  section,  Society  of  Chemical  Industry,  consist- 
ing of  W.  F.  Hillebrand  and  Clifford  Richardson.  For  exact  work  it 
is  desirable  that  these  methods  be  closely  followed.  They  are  not  intended 
for  use  in  making  the  rapid  determinations  which  are  necessary  for  the 
control  of  the  mix  when  the  plant  is  in  operation.  A  method  of  rapid 
analysis  has  recently  been  published  by  several  members  of  the  Lehigh 
section,  American  Chemical  Society,  which  is  probably  well  adapted 
for  use  in  the  Lehigh  cement  district;  but  it  is  doubtful  if  it  is  worth 
while  attempting  to  formulate  standard  methods  for  rapid  analysis, 
since  the  requirements  vary  so  much  at  the  different  plants. 

Method   Suggested   for   the    Analysis    of   Limestones,    Raw  Mixtures 
and  Portland  Cements.* 

Solution. — One-half  gram  of  the  finely  powdered  substance  is  to 
be  weighed  out  and,  if  a  limestone  or  unburned  mixture,  strongly  ignited 
in  a  covered  platinum  crucible  over  a  strong  blast  for  fifteen  minutes, 
or  longer  if  the  blast  is  not  powerful  enough  to  affect  complete  con- 
version to  a  cement  in  this  time.  It  is  then  transferred  to  an  evapora- 
ting dish,  preferably  of  platinum  for  the  sake  of  celerity  in  evapora- 
tion, moistened  with  enough  water  to  prevent  lumping,  and  5  to  10  c.c. 
of  strong  HC1  added  and  digested,  with  the  aid  of  gentle  heat  and  agita- 
tion until  solution  is  completed.  Solution  may  be  aided  by  light  pres- 
sure with  the  flattened  end  of  a  glass  rod. f  The  solution  is  then  evapo- 
rated to  dryness,  as  far  as  this  may  be  possible  on  the  steam-bath. 

*  Eng.  News,  50,  p.  60.     Eng.  Record,  48,  p.  49.     Cement,  Sept.,  1903. 

t  If  anything  remains  undecomposed  it  should  be  separated,  fused  with  a 
little  Na2CO3,  dissolved  and  added  to  the  original  solution.  Of  course,  a  small 
amount  of  the  separated  non-gelatinous  silica  is  not  to  be  mistaken  for  undecom- 
posed matter. 


CONSTITUTION,  ETC ,  OF  PORTLAND   CEMENT. 


577 


TH  coi-i          IO<M  looo  ** 

i-O  T~-(  "^  <O  CO  I~H  t^*  CO  CO 


CO 
1C 


»  :^^ 

C     •'  O  '-i 


'-lClT-iCMOi— i<M<N(MO(N(N 


lO        OOCN        (NCitOcOO 
CO        rH  GO        1C  l>  CO  CC  »O 


OOOO^     (M  O5  O  r~lS<~S°° 

CO         T^O        i— I  CQ  CO  GO  CM         iC^OcOt^-  W  1>O 

l>        OO  00        1C  1>  l>  Tf  CO        l>l>OOOi  1>  00  X 


-V 
C 

!-•= 


O 


3  ^'  c  "o    .3  ;  c  aj  3  :  ! 
ISS?:   8,181'afti 


. 

6S 


578 


CEMENTS,  LIMES,  AND  PLASTERS. 


tO  O  CM  CM  _J  CO  GO  O  CO   rfi  CO  to  to   to  O5  "*  OC  O5  i— i  O  O  O  CO   t>»   O»OT-* 
CM  CO  T-H  CM  "  ^  !>•  i~H  to  to   OS  OS  t^*  1-"^   CM  t^  00  CO  ^  00  to  to  ^  TH   CO   ^O  ^^  to 

T— (i— li— (i— (CCMr— IT— li— I          i— (  i— i  i— I  TH          OOOi— li— 'i— IT— lOrHrH          TH          rHi-Hi— I 


^;       C1 

^^  ^^          ^^  rv           %**                               »^      * 

'"^ 

Cs  CT-I          CT^  C^l          W                 T—          113 

•    •  o   o 

0 

~*  ._.  \.-^  \.-*/  \^  i.  ~    \i>  **^  %i-  ^^*  v_ i  "^  \j-  \^^/   r  CO  to  O  O  !^  CM  i^  CO   CO  r-H  O5 
CO  CO -^  CM  i— i  ^  to  Tf  00  CM   CO  X  O  i— '  GO  CM  CO  CO  ™  ^  O5  00  O  •*  i— i  1>  CO   tO  CO -^ 

CMCMi-HrHrH    CCOi-ii-ii-i         CMi-MCMi-iCMOrHO    CJCOCMCMi-lOCOTHCJ        CM  CM  CM 


t^  CO  Oi  CO  <N  O  O5  00  iO  l>   TH  CO  O  *C  O  CM 


OOO 
Oi  1-1  X 


to  o:  <q 


<M  t^  CO  TH  CO  ^H 


x<5 

|  I 

o  ^ 

li 

a  a 

i! 
H: 

H 

05 


CO  00  CO  00  O5  i—  i  i—  I  O  '     "     'O 
CO  TJH  TF  CO  Oi  CO  •*  t>-  CX) 


co  co 


»OCO 
1>  CO 


iO  GO 
C5<N 


I>  >O  O  CO  GO  CO  i-> 
CO  GO  CO  GO  i-H  CO  00 


O  O5O5  CO^rH  COCMOO5O5 

tO  00  tO  O  CO  CO  "*  CM     T        CM  rH  J>  O        O  O5        CM  CO  CO  O  rH  00  tO 

!>.  l>  CO  CO  CO  O  CO  00  O5  t>.  COCO        t^  CO 


•^i  GO  GO  -^f  ^  O  ^f  00      O     O  CO  00  O5  CO  O  tO  O  i—  i  -*  CO  O  l>-  CO  O5  CM  00  to  O  "f  i—  i  O5 
1-1  O  ^  C5Tt<  00  OO5     to     COOO  Oi-i  CO(N  t>00  CO  O  O5  COOOiN  Oi  O5  O-*  Oi  O  CO  (N 


O 
(M 


CO  O  <N  rH     1-1     ^H  ^-t  T-H  CO  1-1  1-1  O  T-H  CM  i-t  rH  T-H  O  CO  O  C5  <N  <M  (N  T-H  (M  (N 
CMCMCM(M      CM      CMCM<MCMCMCMCMCMCMCMCMCMCMCMCMi-HCMCMCMCMCMCM 


p^  «d,  CL, 

c'|3        ^ 

02    O    02  "•      •*       OH-      <• 


•9  S^ 


O  O 

If  I 


A 


CONSTITUTION,  ETC.,  OF  PORTLAND  CEMENT, 

i 


579 


if 


t 


O    flH 

T  2 


^  s 

B  S 

H3  <1 

W  r 

j3  s 


OS  O  CO  CO  Tfi  <N   OI-H  00  QC  00  O  O  >O  t^  ^  ^ 
Tf  Tji  1C  »O  CO  O   OJ  Tfi  t>-  00  CO  00  00  t>«  CO  *O  CO 


<N  <N  <N  <N  IN  (N  <N  CO  <N  I-H  CC  T-I  O  O  •  <N  1-1  <N 


C^KMC^i-iCOCOCO^C^C^i-HOiO 

CO  ^O  CO  CO  CO  CO  CO  CO  CO  CO  CO  *O  CO 


Ci  CO  l-H  CO  00  1— I  *O  1-1  1— I        -  M-     - 

(N  OS  -tf  00  CO  CO  CO  (N  CO   (N  00  O  l> 

^  ^  <N  <N'  coi  ^-i  IN  TH'  csi  Tjl  TP  S  "*'  <M'  co  <N 


i  »-i  iO  rt<  i-(  1C  O  O  CO 

1  1>-  c^  i>   co  Oi  rr  os 


580  CEMENTS,  LIMES,  AND  PLASTERS. 

Silica. — The  residue,  without  further  heating,  is  treated  at  first  with 
5  to  10  c.c.  of  strong  HC1.  which  is  then  diluted  to  half  strength  or  less, 
or  upon  the  residue  may  be  poured  at  once  a  larger  volume  of  acid  of 
half  strength.  The  dish  is  then  covered  and  digestion  allowed. to  go 
on  for  ten  minutes  on  the  bath,  after  which  the  solution  is  filtered  and 
the  separatecj  silica  washed  -thoroughly  with  water.  The  filtrate  is 
again  evaporated  to  dryness,  the  residue,  without  further  heating, 
taken  up  with  acid  and  water,  and  the  small  amount  of  silica  it  con- 
tains separated  on  another  filter-paper.  The  papers  containing  the 
residue  are  transferred  wet  to  a  weighed  platinum  crucible,  dried,  ignited, 
first  over  a  Bunsen  burner  until  the  carbon  of  the  filter  is  completely 
consumed,  arid  finally  over  the  blast  for  fifteen  minutes  and  checked 
by  a  further  blasting  for  ten  minutes  or  to  constant  weight.  The  silica, 
if  great  accuracy  is  desired,  is  treated  in  the  crucible  with  about  10  c.c. 
of  HF1  and  four  drops  of  H2SO4  and  evaporated  over  a  low  flame  to 
complete  dryness.  The  small  residue  is  finally  blasted  for  a  minute 
or  two,  cooled,  and  weighed.  The  difference  between  this  weight  and 
the  weight  previously  obtained  gives  the  amount  of  silica.* 

A1203  and  Fe2O3:  The  filtrate,  about  250  c.c.  from  the  second 
evaporation  for  Si02,  is  made  alkaline  with  NH4OH  after  adding  HC1, 
if  need  be,  to  insure  a  total  of  10  to  15  c.c.  strong  acid,  and  boiled  to 
expel  excess  of  NH3,  or  until  there  is  but  a  faint  odor  of  it,  and  the  pre- 
cipitated iron  and  aluminum  hydrates,  after  settling,  are  washed  once 
by  decantation  and  slightly  on  the  filter.  Setting  aside  the  filtrate, 
the  precipitate  is  dissolved  in  hot  dilute  HC1,  the  solution  passing  into 
the  beaker  in  which  the  precipitation  was  made.  The  aluminum  and 
iron  are  then  precipitated  by  NH4OH,  boiled  and  the  second  precipi- 
tate collected  and  washed  on  the  same  filter  used  in  the  first  instant. 
The  filter-paper,  with  the  precipitate,  is  then  placed  in  a  weighed  platinum 
crucible,  the  paper  burned  off  and  the  precipitate  ignited  and  finally 
blasted  5  minutes,  with  care  to  prevent  reduction,  cooled  and  weighed 
as  Al203  +  Fe203.t 

Fe203:  The  combined  iron  and  aluminum  oxides  are  fused  in  a 
platinum  crucible  at  a  very  low  temperature  with  about  3  to  4  grams 
of  KHS04,  or,  better,  NaHSO4,  the  melt  taken  up  with  so  much  dilute 
H2S04  that  there  shall  be  no  less  than  5  grams  absolute  acid  and  enough 
water  to  effect  solution  on  heating.  The  solution  is  then  evaporated 
and  eventually  heated  till  acid  fumes  come  off  copiously.  After  cooling 

*  For  ordinary  control  jvork  in  the  plant  laboratory  this  correction  may,  perhaps, 
be  neglected;  the  double  evaporation  never. 

f  This  precipitate  contains  TiO2,  P2O5,  Mn3O4. 


CONSTITUTION,  ETC.,  OF  PORTLAND  CEMENT.  581 

and  redissolving  in  water  the  small  amount  of  silica  is  filtered  out, 
weighed,  and  corrected  by  HF1  and  H2SO4.*  The  filtrate  is  reduced 
by  zinc-  or  preferably  by  bydrogen  sulphide,  boiling  out  the  excess  of 
.the  latter  afterward  while  passing  C02  through  the  flask,  and  kitrated 
with  permanganate. f  The  strength  of  the  permanganate*,  solution 
should  not  be  greater  than  .0040  grains  Fe^Oa  per  c.c.  ;.\, j 

CaO:  To  the  combined  filtrate  from  |Jie  Al203rjrf.IfeQ3*  precipitate 
a  few  drops  of  NH4OH  are  added,  and  the  solution  brougj^t  to  boiling. 
To  the  boiling  solution  20  c.c.  of  a  saturated  solution  of  ammonium 
oxalate  is  added,  and  the  boiling  continued  until  the  precipitated 
CaC2C>4  assumes  a  well-defined  granular /orm.  It  is 'then  allowed  to 
stand  for  20  minutes,  or  until  the  precipitate  has  settled,  and  then  filtered 
and  washed.  The  precipitate  and  filter  are  placed  wet  in  a  platinum 
crucible,  and  the  paper  burned  off  over  a  small  flame  of  a  Bunsen  burner. 
It  is  then  ignited,  redissolved  in  HC1,  and  the  solution  made  up  to  100 
c.c.  with  water.  Ammonia  is  added  in  slight  excess,  and  the  liquid 
is  boiled.  If  a  small  amount  of  A12Q3  separates,  this  is  filtered  out, 
weighed,  and  the  amount  added  to  that  found  in  the  first  determina- 
tion, when  greater  accuracy  is  desired.  The  lime  is  then  reprecipitated 
by  ammonium  oxalate,  allowed  to  stand  until  settled,  filtered,  and 
washed,  t  weighed  as  oxide  by  ignition  and  blasting  in  a  covered 
crucible  to  constant  weight,  or  determined  with  dilute  standard  per- 
manganate.§ 

AlgO:  The  combined  filtrates  from  the  calcium  precipitates  are 
acidified  with  HC1,  and  concentrated  on  the  steam-bath  to  about  150 
c.c.,  10  c.c.  of  saturated  solution  of  N"a(NH4)HP04  are  added,  and 
the  solution  boiled  for  several  minutes.  It  is  then  removed  from  the 
flame  and  cooled  by  placing  the  beaker  in  ice- water.  -After  cooling, 
NH4OH  is  added  drop  by  drop  with  constant  stirring  until  the  crystal- 
line ummonium  magnesium  orthophosphate  begins,  to  form,  and  then 
in  moderate  excess,  the  stirring  being  continued  for  several  minutes. 
It  is  then  set  aside  for  several  hours  in  a  cool  atmosphere  and  filtered. 


*  This  correction  of  A12O3,  Fe2O3,  for  silica  should  not  be  made  when  the  HF1 
correction  of  the  main  silica  has  been  omitted,  unless  that  silica  was  obtained 
by  only  one  evaporation  and  nitration.  After  two  evaporations  and  nitrations 
1  to  2  mg.  of  SiO2  are  still  to  be  found  with  the  Al2O3.Fe2O3. 

t  In  this  way  only  is  the  influence  of  titanium  to  be  avoided  and  a  correct 
result  obtained  for  iron. 

J  The  volume  of  wash-water  should  not  be  too  large,  vide  Hillebrarid. 

§  The  accuracy  of  this  method  admits  of  criticism,  but  its  convenience  and 
rapidity  demand  its  insertion. 


582  CEMENTS,  LIMES,  AND   PLASTERS. 

The .  precipitate  is  redissolved  in  hot  dilute  HC1,  the  solution  made  up 
to  about  100  c.c.;  1  c.c.  of  a  saturated  solution  of  Na(NH4)HP04  added, 
and  ammonia  drop  by  drop,  with  constant  stirring  until  the  precipitate 
is  again  formed  as  described  and  the  ammonia  is  in  moderate  excess. 
It  is  then  allowed  to  stand  for  about  2  hours  when  it  is  filtered  on  a 
paper  or  a  Gooch  crucible,  ignited,  cooled,  and  weighed  as  Mg2P2O7. 

K2O  and  Na2O:  For  the  determination  of  the  alkalies,  the  well- 
known  method  of  Prof.  J.  Lawrence  Smith  is  to  be  followed,  either 
with  or  without  the  addition  of  CaCOs  with  NHCU. 

80s:  One  gram  of  the  substance  is  dissolved  in  15  c.c.  of  HC1, 
filtered  and  residue  washed  thoroughly.* 

The  solution  is  made  up  to  250  c.c.  in  a  beaker  and  boiled.  To  the 
boiling  solution  10  c.c.  of  a  saturated  solution  of  BaCL2  is  added  slowly, 
drop  by  drop,  from  a  pipette  and  the  boiling  continued  until  the  pre- 
cipitate is  well  formed,  or  digestion  on  the  steam-bath  may  be  sub- 
stituted for  the  boiling.  It  is  then  set  aside  overnight,  or  for  a  few 
hours,  filtered,  ignited,  and  weighed  as  BaS04. 

Total  sulphur. — One  gram  of  the  material  is  weighed  out  in  a  large 
platinum  crucible  and  fused  with  Na2C03  and  a  little  KN03,  being  care- 
ful to  avoid  contamination  from  sulphur  in  the  gases  from  source  of 
heat.  This  may  be  done  by  fitting  the  crucible  in  a  hole  in  an  abestos 
board.  The  melt  is  treated  in  the  crucible  with  boiling  water  and  the 
liquid  poured  into  a  tall,  narrow  beaker,  and  more  hot  water  added 
until  the  mass  is  disintegrated.  The  solution  is  then  filtered.  The 
filtrate  contained  in  a  No.  4  beaker  is  to  be  acidulated  with  HC1  and 
made  up  to  250  c.c.  with  distilled  water,  boiled,  the  sulphur  precipitated 
as  BaS04  and  allowed  to  stand  overnight  or  for  a  few  hours. 

Loss  on  ignition. — Half  a  gram  of  cement  is  to  be  weighed  out  in 
a  platinum  crucible,  placed  in  a  hole  in  an  asbestos  board  so  that  about 
three  fifths  of  the  crucible  projects  below,  and  blasted  15  minutes,  prefer- 
ably with  an  inclined  flame.  The  loss  by  weight,  which  is  checked  by 
a  .second  blasting  of  5  minutes,  is  the  loss  on  ignition. 

Note. — Recent  investigations  have  shown  that  large  errors  in  results 
are  often  due  to  the  use  of  impure  distilled  water  and  reagents.  The 
analyst  should,  therefore,  test  his  distilled  water  by  evaporation  and 
his  reagents  by  appropriate  tests  before  proceeding  with  his  work. 

*  Evaporation  to  dry  ness  is  unnecessary,  unless  gelatinous  silica  should  have 
separated  and  should  never  be  performed  on  a  bath  heated  by  gas,  vide  Hillebrand. 


CHAPTER  XXXIX. 
PHYSICAL  PROPERTIES:   TESTING  METHODS. 

THE  utilization  of  Portland  cement  does  not  properly  come  within 
the  province  of  this  volume,  as  it  is  already  covered  by  several  excellent 
books.  An  extensive  and  readily  accessible  literature  has  been  created 
on  the  subject  of  testing  methods  and  testing  results;  but  most  of  this 
literature  is  more  important  to  the  professional  cement-tester  than  to 
the  cement-manufacturer  or  cement-user.  In  the  present  chapter  the 
subject  of  testing  will  necessarily  be  considered,  but  merely  incidentally. 
Stress  will  be  laid,  on  the  other  hand,  on  the  general  properties  which 
Portland  cement  develops  in  use,  and  attention  will  be  directed  to  the 
chemical  and  physical  agencies  which  operate  to  disintegrate,  or  weaken, 
or  destroy  the  cement,  or  the  structures  hi  which  it  is  used. 

Physical  Properties  of  Portland  Cement. 

Portland  cement  13  at  present  used  for  many  different  purposes, 
and  the  use  to  which  it  is  applied  seems  to  be  rapidly  increasing.  Under 
such  circumstances  it  is  necessary  to  supply  a  product  well-fitted  to 
withstand  the  various  disintegrating  agencies  to  which  it  may  be  sub- 
jected. 

In  its  ordinary  uses,  hi  heavy  masonry  for  example,  the  cement 
will  be  subjected  to .  compressive  stresses,  but  rarely  to  tensile.  When 
used  as  a  paving  material  it  will  encounter  transverse  stresses  and 
severe  abrasion.  As  a  lining  material  its  imperviousness  will  be  tested. 
In  other  places,  as  in  gun  emplacements  for  example,  it  may  be  sub- 
jected to  severe  and  often-repeated  shocks. 

To  these  physical  agencies  of  disintegration  or  destruction,  are  added 
chemical  agents,  which  are  at  times  of  paramount  importance.  Works 
exposed  to  sea-water,  for  example,  are  subject  to  purely  chemical  attack 
which  must  be  guarded  against  so  far  as  possible. 

The  situation  might  be  summed  up  by  stating  that  cement  may 
fail  through  defects  in  its  manufacture  (internal  agencies),  or  through 

583 


584 


CEMENTS,  LIMES,  AND  PLASTERS. 


the    purely   external  agencies,  and  that  these  agencies  may  be  either 
physical  or  chemical. 

This  brief  outline  will  serve  to  give  some  idea  of  the  wide  scope 
which  might  be  given  to  a  discussion  of  the  properties  of  Portland 
cement. 

,  ALL  PASQED  NO.  lOC^SIEVE  . 
o  o  §  '  o  o  _  ' 


> 

/ 

87$  P 

^SSED 

MO.  100 

SIEVE 

-S 

/ 

/ 

/* 

p 

ASSED 

TO^A-rfD 

STOPP 

ED  ON 

100  SIE 

VE 

/ 

/ 

?> 

SSED  5 

0  AND 

STOPPl 

D  ON  ' 

0  SIEV 

FIG.  143.* — Variation  of  tensile  strength  with  fineness. 

Value  of  fineness  tests.— The  reason  for  testing  the  fineness  of  a 
•cement  depends  on  the  facts  that  (a)  the  strength  of  the  cement,  and 
particularly  its  tensile  strength  when  mixed  with  sand,  increases  with 
the  fineness,  and  (6)  the  soundness  of  the  cement  may  be  improved 
by  fine  grinding.  The  second  point  is  one  that  concerns  the  manu- 
facturer more  than  the  user,  because  an  unsound  cement  will  usually 
fail  to  pass  other  tests  and  will  therefore  be  rejected. 

The  increase  in  strength  consequent  on  increased  fineness  is  well 
shown  in  Figs.  143  and  144,  both  showing  the  results  of  tests  on  1:3 
mixtures,  the  tests  of  Fig.  143  having  been  made  at  four  months  while 
those  in  Fig.  144  are  at  various  ages. 

The  value  of  fine  grinding  is  evident,  and  engineers  are  constantly 
raising  the  standard  of  fineness  in  specifications.  Unfortunately,  how- 
ever, they  fail  to  make  proper  use  of  this  fine  cement  after  they  have 
paid  extra  for. getting  it.  They  insist,  for  example,  in  obtaining  cement 
which  will  pass  92  or  95  per  cent  through  a  100-mesh  sieve,  and  then 
use  it  in  the  same  sand  mixtures  that  they  would  if  it  were  an  English 
cement  passing  perhaps  85  per  cent  through  100-mesh. 

The  actual  fineness  of  a  number  of  typical  American  Portlands  is 
shown  very  exactly  in  the  tests  given  in  Table  222. 

*  From  Johnson's  "  Materials  of  Construction",  p.  409. 


PHYSICAL  PROPERTIES  OF  PORTLAND  CEMENT. 


585 


TABLE  222. 
FINENESS  OF  VARIOUS  AMERICAN  PORTLANDS. 


(BLEININGER.) 


Diam- 

Diam- 

Diam- 

Residue 

Residue 
on 

Residue 
on 

eter 
between 

eter 
between 

eter 
between 

Finer 

Total 
Coarser 

Brand. 

Reduced  on. 

80-mesh 
Sieve. 

120- 
mesh 
Sieve. 

200- 
mesh 
Sieve. 

0.008 
and 
0.002 

0.002 
and 
0.0002 

0.0003 
and 
0.0007 

Last 
Size. 

than 
200- 
mesh.  i 

Inches. 

Inches. 

Inches. 

1 

Tube  miU.  . 

7.07 

14.56 

4.45 

22.  CS 

19.29 

7.36 

24.69 

25.98 

2 

(         i 

9.01 

15  35 

5.09 

21.50 

20.53 

7.06 

21.52 

29.45 

3 

e             e 

12.12 

15.05 

7.61 

21.11 

16.85 

5.91 

21.37 

34.78 

4 

(            e 

14.11 

14  57 

7.82 

22.43 

13.95 

„   7.81 

19.32 

36.49 

5 

e            t 

3  84 

17  64 

5  1C 

25  27 

12  56 

10  16 

20  42 

26  58 

6 

Gr  ffin  mill.  . 

3^06 

15.41 

8.24 

28  .  56 

16.48 

12.74 

15.51 

26.72 

7 

<              c 

9.43 

16.91 

6.37 

25.52 

12.18 

9.20 

18.49 

32.71 

8 

e             t 

5  00 

15  42 

14  52 

27  30 

19  10 

9  22 

14  88 

29.53 

9 

i             e 

4.40 

11.35 

5.13 

23  .  79 

21.30 

10.01 

24.01 

20.89 

10 

e             ( 

4.18 

13.30 

5.07 

22.63 

14.64 

12.31 

28.79 

22.55 

Specific  gravity. — The  specific  gravity  of  a  Portland  cement  is  a 
property  which  is  of  no  importance  of  itself  to  the  engineer.  The 
reason  for  determining  it  is  in  order  to  rule  out  underburned  or  adul- 


400 


V 


3000 


2000 


1000 


COMPRESSION 


10 


15 


20 


25  0  5 

AGE  IN   DAYS 


10 


15 


20 


25 


•30 


FIG.  144.* — ^Effect  on  strength  of  regrinding  cement.      (Tetmajer.) 

terated  cement.  The  specific  gravity  of  a  well-dried  sample  of  Port- 
land cement  will  rarely  fall  below  3.10;  while  that  of  a  natural  cement, 
a  slag  cement,  or  a  Portland  adulterated  with  slag  wrill  rarely  rise  above 


*  From  Johnson's  "  Materials  of  Construction  ",  p.  411. 


586 


CEMENTS,  LIMES,  AND  PLASTERS. 


3.00.     Some  few  American  natural  cements  do,  however,  show  a  higher 
specific  gravity,  as  can  be  seen  from  the  table  on  page  263. 

Setting  properties. — A  certain  minimum  time  of  initial  and  final  set 
is  usually  specified,  for  the  convenience  of  the  workmen.  This  is  regu- 
lated by  the  use  of  gypsum  or  plaster  at  the  plant,  a  practice  whose 
effects  have  been  discussed  -in  detail  jji  Chapter  XXXVI. 


CURVE  OF  TIME  BEFORE 
SETTING  IS  COMPLETED. 


u 


.8  IN  MIN 


zm: 

30      S5      40      45      50°  C. 


\ 


CURVE  OF  TIME  BEFORE 
SETTING  BEGINS. 


co|\ 


1.5  IN  MIN 


0        6       10      15      20     25      30      35      40      45     50  C. 

FIG.  145.* — Effect  of  temperature  on  setting  time. 

The  effect  of  temperature  on  the  setting  of  Portland  cement  is  well 
shown  in  Fig.  145.  It  will  be  noted  that  the  setting  is  much  slower  at 
low  than  at  high  temperatures,  within  the  limits  of  the  experiments. 

Tensile  strength. — The  tensile  strength  of  a  cement  is  of  very  little 
importance  or  interest  of  itself,  because  cements  are  rarely  subjected 
intentionally  to  tensile  strains.  But  in  practice  the  tensile  test  is  the 


*  From  Johnson's  "Materials  of  Construction,"  p,  616. 


PHYSICAL  PROPERTIES  OF  PORTLAND  CEMENT.  587 


Age  of  briquettes. 
Fid   146. — Tensile  strength  of  various  classes  of  cements.     (Philadelphia  tests,  1899.) 


588 


CEMENTS,  LIMES,  AND  PLASTERS. 


most  commonly  applied  of  all  tests,  this  action  being  based  on  the 
assumption  that  the  ratio  between  compressive  and  tensile  strength 
for  all  Portland  cements  is  quite  uniform,  and  that  therefore  varia- 
tions in  tensile  strength  will  indicate  corresponding  (though  much 
greater)  variations  in  compressive  strength.  This  assumption  is  to  a 
large  extent  correct,  and  for  all  practical  purposes  may  be  considered 
satisfactory.  The  question  as  to  the  ratio  existing  between  the  two 
types  of  strength  will  be  taken  up  on  a  later  page  (p.  589.) 

In  Fig.  146  the  results  of  a  large  series  of  tests  on  various  classes  of 
cement  are  shown  diagrammatically.  The  cements  tested  included 
American  and  foreign  Portlands,  foreign  "natural  Portlands",  and  Amer- 
ican natural  cements,  and  the  comparative  results  are  quite  represen- 
tative. 

600  r 


400 


30 

AGE  IN  WEEKS 


FIG.  147.* — Effect  of  proportions  of  sand  on  tensile  strength. 

The  three  points  of  most  general  interest  in  connection  with  tests  of 
tensile  strength  are  (a)  the  decrease  in  tensile  strength  with  increase 
of  percentage  of  sand,  (6)  the  increase  in  strength  with  increased 
age,  and  (c)  the  variation  in  strength  due  to  differences  in  the  character 
of  the  sand.  Two  of  these  points  are  illustrated  in  Figs.  147  and  148, 
while  all  three  are  constantly  discussed  in  engineering  publications. 

Compressive  strength. — The  compressive  strength  of  a  cement  or 
concrete  is  a  matter  of  direct  practical  importance,  for  these  materials 
are  rarely  subjected  to  any  other  type  of  strain  when  used  in  actual 


*  From  Johnson's  "  Materials  of  Construction",  p.  571. 


PHYSICAL  PROPERTIES  OF  PORTLAND  CEMENT. 


580 


work.  Compressive  tests,  however,  require  the  use  of  heavy  testing 
machines,  and  are  therefore  not  adapted  for  field  or  ordinary  office  tests. 
(See  Tables  223  and  224.) 


800 


i 

2400 


6200 


A 


A 


2468 
PROPORTIONS  OF  SAND  TO  1  CEMENT 


10 


FIG.  148.* — Effect  of  character  of  sand  on  tensile  strength. 

TABLE  223. 
COMPRESSIVE  STRENGTH  OF  PORTLAND-CEMENT  CUBES,  WATERTOWN  ARSENAL. 


Brand. 

Per  Cent 
Water. 

Compressive  Strength, 
Pounds  per  Square  Inch. 

7  Days. 

1  Month. 

3  Months. 

8580 
5870 
6310 
6980 
8170 
8180 
7720 
5930 
7730 
6810 
7630 
5510 
4660 

Alpha         

25 
25 
26.8 
18 
22.5 
25 
30 
22.5 
25 
30 
25 
29.2 
26.7 

6010 
3490 
4280 
5780  : 
5960 
6320 
6340 
4620 
5560 
5030 
5630 
3510 
2750 

7340 
5370 
5590 
5990 
7080 
6750 
6850 
5180 
5980 
5620 
6640 
4940 
4030 

Atlas          

Lehigh     

n 

Star  with  plaster 

(         '          (C                   It 

I                      ((                   (  C 

1        without  plaster                ...    .    .    ... 

(             a            (i 

I                          11                       (C 

Whitehall     

Alsen      

Josson  .  .  .  .  t  

Report  on  Tests  of  Metals,  etc.,  at  Watertown  Arsenal,  1902,  pp.  369-376. 

Ratio  of  compressive  to  tensile  strength. — For  a  given  age  and 
mixture,  the  ratio  between  the  compressive  and  tensile  strength  of  a 
Portland-cement  mortar  is  practically  fixed.  The  ratio  increases  with 
inc£easing  age,  and  also  increases  with  increasing  proportions  of  sand. 

*  From  Johnson's  "  Materials  of  Construction",  p   581. 


590 


CEMENTS,  LIMES,  AND  PLASTERS. 


In  Fig.  149  are  plotted  the  curves,  by  Johnson,  resulting  from  compari- 
son of  a  large  series  of  tests  by  Tetmajer  on  1:3  mixtures. 

TABLE  224. 

COMPRESSIVE  STRENGTH  OP  PORTLAND-CEMENT  MORTAR  AND  CONCRETE  CUBES, 

WATERTOWN  ARSENAL. 


Brand. 

Composition. 

v* 

Age. 

Size  of 
Cube, 
Inches. 

Compres- 
sive 
Strength 
per  Square 
Inch. 

Cement. 

Sand. 

Stone. 

Years. 

Months. 

Days. 

Atlas  *.  . 

1 
1 
1 
1 
1 
1 
1 
1 
1 
1 
1 
1 
1 

1 

1J 

2 

2* 
3 
3* 
4 
2 
3 
2 
2 
2 
3 

4 

6 
4 
4 
4 
5 

2 
2 
2 
2 
2 
2 
2 

3 

5 
5 
5 
5 
5 
5 
5 

0* 
1 
2 
3 

20 
19 
16 
17 
15 
13 
12 
7 
7 
12 
22 
25 
2 

6 
6 
6 

6 

6 
6 

6 
12 
12 
12   * 
12 
12 
12 

11,330 
10,390 
9,520 
8,110 
6,140 
6,280 
5,230 
1,303 
1,053 
2,615 
3,392 
4,135 
3,758 

* 

* 

* 

* 

* 

* 

* 

* 

Alpha  *  

Vulcanite  f  .  . 
t.- 
Grant  f 

*  Report  on  Tests  of  Metals,  etc.,  at  Watertown  Arsenal,  1902,  pp.  512-514. 
t  Ibid.,  1900,  pp.  1105-1111. 


TENSILE  STRENGTH  ^ 
00  «o  o 

-.^- 

^ 

^^ 

^\ 

c^ 

•~^"~ 

f^ 

^ 

^"' 

£ 

V? 

^ 

/  /  * 

/ 

$ 

' 

/i 

7 

'// 

I 

. 

i 

* 

J                 2                  4                 6                  8                 10               13 
AGE  IN  MONTHS 

FIG.  149.  t — Ratio  of  compressive  to  tensile  strength.     (Johnson.) 
J  From  Johnson's  "  Materials  of  Construction",  p.  419. 


PHYSICAL   PROPERTIES  OF  PORTLAND  CEMENT. 


591 


In  practical  use,  it  may  be  assumed  that  at  the  end  of  a  year  the 
average  Portland-cement  mortar  will  have  a  compressive  strength 
about  ten  times  as  great  as  its  tensile  strength. 

In  Table  225  are  given  the  results  of  a  series  of  tests  carried  out 
at  the  Watertown  Arsenal.*  The  tensile  tests  were  made  on  the  usual 
briquettes,  the  compressive  tests  on  2-inch  cubes,  and  each  average 
given  is  the  result  of  ten  tests.  The  cement  used  was  the  Peninsular 
brand,  giving  the  following  results  for  fineness  and  specific  gravity. 

Per  cent  of  fineness: 

Retained  on  98  X  ICO  sieve 4 . 95 

Passed  by  98X100  sieve;  retained  on  174X182  bolting-cloth  19.75 
Passed  by  174X 182  bolting-cloth 75.30 

Specific  gravity: 

As  taken  from  barrel 3 . 20 

After  mixing  with  22  per  cent  water,  setting  7  days  in  air, 

regrinding,  and  heating  to  a  constant  weight  at  110°  C  . .     2.81 

A  chemical  analysis  of  the  cement  is  also  given,  but  is  evidently 
erroneous  and  therefore  will  not  be  quoted  here. 

TABLE  225. 
RELATION  OF  TENSILE  TO  COMPRESSIVE  STRENGTH.     (WATERTOWN  ARSENAL.) 


Per  Cent 
_f 

Ages  in 

Tensile  Strength,  Pounds 
per  Square  Inch. 

Compressive  Strength,  Pounds 
per  Square  Inch. 

Ol 

Water. 

Air, 
Days. 

Water, 
Days. 

Maximum. 

Minimum. 

Average. 

Maximum. 

Minimum. 

Average. 

20 

1 

221 

177 

196 

801 

654 

717 

20 

7 

393 

301 

354 

3430 

2700 

3040 

20 

28 

641 

487 

566 

4370 

3490 

3990 

20 

1 

6 

835 

653 

780 

4830 

3770 

4250 

20 

1 

27 

952 

857 

906 

8280 

5730 

7370 

22 

1 

209 

156 

189 

670 

530 

595 

22 

7 

.  . 

482 

303 

392 

3680 

3010 

3260 

22 

28 

518 

421 

457 

4310 

3030 

3760 

22 

1 

°6 

724 

502 

666 

5370 

3620 

4720 

22 

1 

27 

1010 

782 

866 

7810 

5360 

6870 

25 

1 

.  . 

223 

148 

190 

450 

398 

430 

25 

7 

475 

301 

402 

3210 

2120 

2610 

25 

28 

552 

393 

450 

3550 

2630 

3130 

25 

1 

6 

388 

251 

329 

4440 

3360 

3880 

25 

1 

27 

807 

696 

758 

8740 

6310 

7580 

Modulus  of  elasticity. — The  determinations  of  the  modulus  of  elas- 
ticity given  in  the  following  table  were  made  at  the  Watertown  Arsenal. 


*  Report  on  Tests  of  Metals,  etc.,  at  Watertown  Arsenal  during  1902,  p.  511. 
1903. 


592 


CEMENTS,  LIMES,  AND  PLASTERS. 
TABLE  226. 


Brand. 

Composition. 

Weight 
per  Cubic 
Foot, 
Pounds. 

Age. 
Mos.    Dys. 

Ultimate 
Strength, 
Pounds 
per 
Square 
Inch. 

„                    Pounds  per 
"•                  Square  Inch. 

Alpha  

Neat 

135.5 

•f* 
1          ' 

/  #(500-2000)    =3,000,000 

\  £"(500-3000)    =3,030,000 

ii 

ft 

[£(500-2000)    =3,488,000 

135.5 

7     %if 

8530 

•1  £(2000-4000)  =3,279,000 

[  £(4000-6000)  =2,963,000 

it 

it 

137.3 

1  ;..:-.. 

£(500-2000)    =3,061,000 

f  £(500-2000)    =4,545,000 

i  ( 

It 

137  .  3 

-5    V... 

9260 

\  £(2000-4000)  =4,255,000 

..    ».  .. 

[  £(4000-6000)  =3,846,000 

Atlas 

({ 

134.7 

2J     .  . 

£(500-2000)    =2,326,000 

it 

ft 

134.7 

64 

5450 

/  £(500-2000)    =2,479,000 

\j  2,          •   • 

\  £(2000-4000)  =2,581,000 

Lehigh.  .  .  . 

It 

129.2 

1       26 

5800 

J  £(500-2000)    =2,500,000 
\  £(2000-4000)  =2,353,000 

(  ( 

1  cement  :  1  sand 

133 

1       26 

3420 

£(500-2000)    =2,778,000 

I  C 

Neat 

135.9 

1       26 

7540 

/  7?  (500-2000)    =4,348,000 
\  £(2000-3000)  =4,444,000 

f  £(500-2000)    =3,571,000 

Peninsular  . 

it 

135.3 

2       13 

6710 

£(2000-3000)  =3,448,000 

-      •  .-*•  •.. 

I  £(3000-4000)  =3,125,000 

f  £(500-2000)    =  3,846,000 

it 

{  ( 

138.0 

2       14 

6720 

\  £(2000-3000)  =3,571,  000 

I  £(3000-4000)  =3,509,000 

(i 

1  cement  :  1  sand 

133.4 

2       13 

4200 

/  £(500-2000)    =2,941,000 
\  £(2000-3000)  =2,439,000 

Sand  cement. — Sand  cement,  or  silica  cement,  is  the  name  given  to 
the  product  made  by  grinding  up  together  Portland  cement  with  an 
equal  or  greater  quantity  of  sand,  limestone,  or  other  chemically  inert 
substance.  Description  of  the  making  and  properties  of  sand  cement 
is  not  properly  part  of  a  discussion  of  the  manufacture  of  Portland  cement, 
but  rather  a  matter  for  the  engineer  to  consider  in  connection  with  the 
uses  of  cement.  For  this  reason  the  question  will  be  touched  on  very 
briefly. 

It  is  found  that  if  Portland  cement  be  mixed  with  an  equal  quantity 
of  sand  or  limestone  and  the  mixture  ground  very  finely  in  a  tube 
mill,  the  resulting  product  (sand  cement)  will  show  a  strength  almost 
or  quite  as  great  as  the  Portland  cement  from  which  it  was  made,  not- 
withstanding the  fact  that  the  sand  cement  consists  only  half  of  Port- 
land cement.  When  Portland  cement  is  very  expensive,  economies 
are,  therefore,  possible  in  this  line. 

The  gain  in  strength  is  due  entirely  to  the  extra  fineness  given  by 
the  extra  grinding.  The  sand  does  not  enter  into  chemical  combina- 


PHYSICAL  PROPERTIES  OF  PORTLAND  CEMENT. 


593 


tion  with  the  cement  in  any  way,  for  ground  limestone  will  give  as  good 
results  as  ground  quartz. 


150  200 

AGE  IN   DAYS 


300 


350 


FIG.  150.* — Strength  of  sand-cement  mortar.  The  first  figure  on  each  curve  de- 
notes parts  of  Portland  cement;  the  second,  parts  of  ground  sand;  the  third, 
parts  of  uiiground  sand. 

The  tests  quoted  in  Table  227  were  made  at  Albany  in  the  labora- 
tory of  the  State  Engineer.  Iron  Clad  is  a  Portland  cement  of  high 
grade,  while  Victor  is  the  sand  cement  made  from  it  by  grinding  Iron 
Clad  with  limestone. 


*  From  Johnson's  "Materials  of  Construction",  p.    579. 


594 


CEMENTS,  LIMES,  AND  PLASTERS. 


TABLE  227. 
COMPARATIVE  TESTS  OF  PORTLAND  CEMENT  AND  SAND  CEMENT. 


Cement. 

Fineness. 

Setting-time, 
Minutes. 

Tensile  Strength, 
Pounds. 

50-Mesh. 

lotf-Mesh 

Initial. 

Final. 

7  Days. 

28  Days. 

1897.     Iron  Clad,  1:3  

100 
100 

94f 
96 

51 

35 

122 
79 

170 

198 

274 
265 

Victor,        1:3  

1898.     Iron  Clad,  1  :  3 

99£ 
100 

94i 
96 

27 
41 

81 
89 

189 
184 

277 
272 

Victor,        1:3  

1899.     Iron  Clad,  1:3  
Victor,        1:3  

100 
100 

98 
100 

45 
60 

94 
158 

207 
178 

311 
264 

TABLE  228. 
TENSILE  AND  COMPRESSIVE  STRENGTH  OF  SAND  CEMENTS.     (SMITH.) 


Name  of  brand  

Citadel 

Ensign 

Jubilee 

Sand  cement  composed  of  

1  cement 

1  cement 

1  cement 

1  sand 

1  sand 

6  sand 

Fineness:  Passing  100-mesh.  .  ,  

99.8 

99.4 

99  7 

"        120-    " 

99  3 

98  4 

"       180-    "                          .        . 

99  3 

Neat  sand  cement:  Tension,  1  week    

332 

'  '        4  weeks  

475 

1  '        4  months  

810 

340 

"        6       " 

780 

540 

Compression,  4  weeks  

3837 

Sand  cement  1,  sand  1  :  Tension,  1  week    .  .    . 

300 

'  '        2  weeks 

379 

Compression,  1  week.  .  . 





2800 

Sand  cement  1  ,  sand  2  •  Tension  1  week 

184 

'  '        2  weeks 

215 

Compression,  1  week  .  .  . 

1225 

Sand  cement  1,  sand  3:  Tension,  1  week     .... 

135 

189 

'  '        2  weeks  

201 

"         4    "        

141 

'  '        2  months  
Compression,  1  week  .  .  . 
4  weeks.  .  . 

135 

470 
687 

900 

Brickbuilder,  vol.  6,  p.  281. 


PHYSICAL  PROPERTIES  OF  PORTLAND  CEMENT. 


595 


2600 


2000 


cc. 
ui 
o. 

§1500 

z 

1 

z 
Q1000 

i 


500 


\ 


TENSION 


\ 


\ 


PERCENTAGE 


TOTAL8AND  AND  CEMENT 


FIG.  151.* — Strength  of  sand-cement  mortar  with  varying  proportions  of  sand. 


500 


400 


300 


200 


100 


f  IG.  152.  f — Variation  in  strength  of  sand-cement  mortar  when  the  total  proportion 
of  sand  is  constant,  but  the  relative  proportions  of  ground  and  unground  sand 
are  variable. 


*  From  Johnson's  "  Materials  of  Construction  ",  p.  580. 


t  Ibid.,  p.  581 


596 


CEMENTS,  LIMES,  AND  PLASTERS. 


TABLE  229. 
COMPRESSIVE  STRENGTH  OF  SILICA-CEMENT  CUBES.     (WATERTOWN  ARSENAL.) 


\ 

Dimensions  of  Cube. 

Compressive    Strength. 

Per  Cent 
Water. 

Age. 

Height, 

•  .            -i*- 

Surface,  • 

Com- 
pressed 
Area 

Total 

Per 

Square 

Average 
Pounds 

'  Inches. 

Inches. 

Square 
Inches. 

Pounds. 

Inch, 
Pounds. 

per 
Square 
Inch. 

28* 

7  days 

4.05 

4.00X4.06 

16.24 

19,950 

1228 

1 

28| 

i  i 

4.00 

4.09X4.08 

16.68 

22,600 

1355 

28* 

(  ( 

4.03 

3.98X4.13 

16.44 

20,900 

1271 

1    1300 

28| 

(  t 

3.96 

4.03X4.07 

16.40 

19,980 

1218 

28*. 

i  { 

3.96 

4.06X4.10 

16.64 

23,500 

1412 

j 

28| 

1  month 

3.96 

4.15X4.04 

16.77 

27,100 

1616 

28* 

'  l 

3.97 

4.02X4.18 

16.80 

30,600 

1821 

1 

28* 

1  1 

3.96 

4.04X4.07 

16.44 

33,500 

2038 

\    1790 

28* 

t  ( 

3.98 

4.04X4.06 

16.40 

27,900 

1701 

28| 

i  ( 

4.00 

4.13X4.00 

16  .  69 

29,500 

1768 

j 

28* 

3  months 

3.97 

4.01X4.10 

16.44 

32,800 

1995 

j 

28| 

1  1 

3.99 

4.05X4.05 

16V40 

34,100 

2079 

28*. 

1  1 

3.96 

4.08X4.09 

16.69 

34,500 

2067 

j-   2110 

28*. 

(  ( 

3.98 

4.01X4.18 

16.76 

29,200 

2339 

28^ 

e  t 

3.96 

4.05X4.10 

16.61 

34,500 

2077 

j 

28^ 

12  months 

3.96 

4.03X4.19 

16.89 

33,600 

1990 

28| 

<  < 

3.98 

4.07X4.10 

16.69 

39,900 

2390 

>    2190 

18 

8  days 

4.00 

3.92X4.13 

16.19 

47,100 

2910 

1" 

18 

i  ( 

4.06 

3.99X4.00 

15.96 

53,100 

3330 

18 

tt 

4.08 

4.00X3.95 

15.80 

53,400 

3380 

3050 

18 

t  ( 

4.02 

4.06X3.86 

15.67 

43,600 

2780 

18 

'< 

3.99 

3.98X4.08 

16.24 

46,500 

2860 

18 

1  month 

4.00 

4.03X3.98 

16.04 

54,900 

3420 

18 

i  e 

4:00 

4.02X4.08 

16.40 

60,600 

3700 

1 

18 

1  1 

4.08 

4.01X4.00 

16.04 

65,800 

4100 

\    3470 

18 

t  ( 

4.05 

4.01X3.98 

15.96 

39,500 

2480 

18 

i  ( 

4.07 

4.00X4.06 

16.24 

59,400 

3660 

j 

18 

3  months 

4.08 

3.98X4.05 

16.12 

76,100 

4720 

J 

18 

1  1 

4.00 

4.09X4.03 

16.48 

70,500 

4280 

18 

t  ( 

4.08 

4.00X4.02 

16.08 

73,600 

4580 

j.    4470 

18 

(  t 

3.98 

4.05X4.06 

16.44 

70,600 

4290 

\ 

Report  of  Tests  of  Metals,  etc.,  at  Watertown  Arsenal  for  1902,  pp.  376-377.     1903. 

List  of  references  on  sand  cement. — The  following  papers  are  of 
interest  in  this  connection: 

Butler,  M.  J.     Silica  Portland  cement.     Canadian  Engineer,  March,  1899. 
Klein,  O.  H.     Report  on  concrete    foundations  for  pavements.     8vo,  58  pp. 

New  York,  1903.     (Much  criticism  of  sand  cements.) 
Reeves,  H.  E.     The  effect  of  grinding  mixed  sand  and  cement.     Technograph, 

May,  1896. 
Smith,  C.  B.     Sand  cement.      Brickbuilder,  vol.  6,  p.  280.     1897.     (Tests  of 

three  Canadian  brands.     Important  paper.) 


PHYSICAL  PROPERTIES  OF   PORTLAND   CEMENT. 


597 


TABLE  230. 
COMPRESSIVE  STRENGTH  OF  SAND-CEMENT  MORTARS.     (WATERTOWN  ARSENAL.) 


Brand. 

Composition. 

Per  Cent  Age. 

Average  Strength, 
Pounds  per  Square  Inch. 

Months.          Days. 

In  Air. 

In  Water. 

Silica  

Neat 
li 

1  cement,  1  sand 

t  (             ii 

t  f              1  1 

1  cement,  2  sand 

it              t  ( 

t  {              1  1 

1  cement,  3  sand 

t  i              i  i 

«              a 

v 

3 

Y 

3 

1 
3 

1 
3 

7 
6. 
5 

4* 

1670 
2070 
2420 
942 
1460 
1610 
386 
424 
850 
130 
219 
306 

1880 
2830 
3110 
1090 
1920 
2340 
424 
708 
1120     : 
132 
360 
571      . 



Report  of  Tests  of  Metals,  etc.,  at  Watertown  Arsenal,  1902,  p.  443. 

TABLE  231. 

MODULUS  OF  ELASTICITY  OF  SAND  CEMENT.     (WATERTOWN  ARSENAL.) 


Weight 

Brand. 

Mortar. 

per 
Cu.  Ft. 

Time. 
Mos.    Dys. 

Ultimate 
Strength. 

ET                   Pounds  per 
Square  Inch. 

Pounds. 

Silica.  .  . 

Neat 

117.8 

1       28 

2520 

f  #(100-1000)    =1,607,000 
1  #(1000-2000)  =  1,205,000 

tl 

(  t  ' 

116.3 

1       28 

2400 

f  #(100-1000)    =  1  ,475,000 
\  #(1000-2000)  =  1,117,000 

(  ( 

I  cement,  1  sand 

126.9 

1       29 

1200 

#(100-1000)    =1,286,000 

(  ( 

1  cement,  2  sand 

122.4 

1       28 

618 

#(100-500)      =    909,000 

(  ( 

1  cement,  3  sand 

120.8 

1       27 

404 

#(100-400)      =     632,000 

Report  of  Tests  of  Metals,  etc.,  at  Watertown  Arsenal,  1902,  pp.  498-500. 

References  on  sand  cement — (Continued). 
Anon.     The  manufacture  and  use  of  sand  cement.     Engineering  News,  April  16, 

1896. 
Anon.     Le    Silico-Portland    on    silico-cement.      La     Revue    Technologique, 

Jan.  25,  1898. 
Anon.     The  hydraulic  experiment  station  of  Cornell  University.     Engineering 

News,  vol.  41,  pp.  130-133.     March  2,  1899.     (Description  of  use   of 

sand  cement.) 

Effect  of  heating. — The  effect  of  high  temperatures  on  cements  or 
concretes  is,  in  these  days  of  fireproof  construction,  a  matter  of  con- 
siderable interest  to  architects  and  engineers.  In  1902  a  series  of  tests 
along  this  line  were  carried  out  at  Watertown  Arsenal,  some  of  which 
are  summarized  in  Table  232,  below. 


598 


CEMENTS,  LIMES,  AND  PLASTERS. 


These  tests  were  made  on  2-inch  cubes  of  neat  Portland  cement,  all 
being  crushed  at  a  period  of  1  year,  1  month,  and  16  days  after  making. 

"The  cubes  for  this  series  were  prepared  and  set  in  air  or  in  water 
for  a  period  of  one  year  to  a  year  and  a  half  before  they  were  heated, 
and  intervals  ranging  from  four  days  to  nearly  four  months  intervened 
between  the  time  of  heating  and  the^time  of  testing. 

"  The  heated  cubes  were  gradually  raised  to  the  temperatures  recorded, 
and  slowly  cooled  in  dry  sawdust  or  powdered  asbestos.  The  time 
of  heating  was  one  hour,  and  the  maximum  temperature  was  main- 
tained for  one  hour. 

"  Cubes  which  were  set  in  water  were  dried  off  on  a  radiator  for  twenty- 
four  hours  before  heating  in  the  muffle  to  the  temperatures  recorded. 

"  During  heating  some  of  the  cubes  developed  fine  cracks,  at  first  faintly 
shown,  which  enlarged  after  a  few  hours  or  days  had  elapsed.  In  other 
cases  the  cracks  appeared  more  promptly.  Among  those  which  were 
heated  to  the  higher  temperatures  of  the  series,  which  ranged  from  200° 
to  1000°  F.,  there  were  cubes  so  badly  cracked  as  to  be  unsuitable  for 
testing." 

TABLE  232. 
EFFECT  OF  HEATING  ON  COMPRESS: VE  STRENGTH.     (WATERTOWN  ARSENAL.) 


Brand. 

Per  Cent 
Water. 

Heated  to. 

Compressive 
Strength, 
Pounds  per 
Square  Inch. 

Aloha 

25 

not  heated 

9167 

fT 

25 

200°  F. 

8830 

ti 

25 

300°  F. 

7920 

tt 

25 

400°  F. 

9190 

it 

25 

500°  F. 

9400 

tt 

25 

600°  F. 

9000 

et 

25 

700°  F. 

8217 

tt 

25 

800°  F. 

8730 

tt 

25 

900°  F. 

6060 

Dyckerhoff  

29 

not  heated 

5017 

29 

600°  F 

4347 

1  1 

29 

700°  F 

3483 

1  1 

29 

800°  F 

4280 

Report  of  Tests  of  Metals,  etc.,  at  Watertown  Arsenal,  1902,  pp.  459-460 

Effects  of  salt  and  freezing. — The  use  of  cement  or  concrete  in  build- 
ings constructed  during  very  cold  weather  has  led  to  a  long  series  of 
experiments,  designed  to  determine  the  effects  of  using  salt  and  other 
anti-freezing  agents  in  the  water  used  in  mixing  the  mortar. 

The  results  of  a  number  of  such  tests  are  shown  diagrammatically 
in  Figs.  153  to  158  inclusive.  The  results  as  to  strength  are  rather  con- 


PHYSICAL  PROPERTIES  OF  PORTLAND  CEMENT, 


599 


tradictory,  but  it  seems  probable  that  any  addition  of  salt  will  decrease 
the  ultimate  tensile  and  compressive  strength  of  the  mortar  in  which 


0  20  40  60  80 

X  PERCENT  SOLUTION 

FIG.  153.* — Effect  on  the  freezing-point  of  cement  of  various  proportions  of 
glycerine,  alcohol,  and  salt.     (Tetmajer.) 


5  10  15  20 

PERCENTAGE  OF  SALT 


FIG.  154. f — Effect  of  salt  on  mortar,  1  cement: 2  sand,  made  in  freezing  weather. 

(Sabin.) 

it  is  used,  but  that  for  the  lower  percentages  of  salt  this  injurious  effect 
may  be  slight  enough  to  be  safely  disregarded. 


*From  Johnson's  "  Materials  of  Construction  ",  p.  615. 
t  Ibid.,  p.  617. 


600 


CEMENTS,  LIMES,  AND  PLASTERS. 


GOO 


to  500 

i 


400 


"6  8  10 

AGE   IN    MONTHS 

FIG.  155.* — Effect  of  salt  on  Portland-cement  mortar,  1  cement: 2  sand,  made  in 
freezing  weather.     (Sabin.) 


AGE  "IN  MONTH'S 

FIG.  156.f — Effect  of  salt  on  tensile  strength  of  mortars,  1  cement  :1  sand  and  1 
cement: 4  sand.  Those  left  in  air  remained  frozen  almost  sixty  days.  Those 
out  in  water  were  first  frozen  in  air  for  three  days. 

*  From  Johnson's  '   Materials  of  Construction  ",  p.  618.  f  Ibid.,  p.  619. 


PHYSICAL  PROPERTIES  OF  PORTLAND  CEMENT. 


601 


7       14       21       28       35       42       49       56       63       70       77       84 
AGE   IN    DAYS 

TENSION 

FIG.  157.* — Effect  of  salt  on  tensile  strength  of  Portland-cement  mortar, 

(Tetmajer.) 


4500 


2000 


1500,; 


14       21       28       35       42       49       56       63       70 
AGE    IN    DAYS 

FIG.  158.* — Effect  of  salt  on  compressive  strength  of  Portland-cement  mortar. 

(Tetmajer.) 


*  From  Johnson's  Materials  of  Construction  ",  p.  620. 
flbid. 


602  CEMENTS,  LIMES,  AND  PLASTERS. 

Effects  of  exposure  to  sea-water. — Portland  cement  is  not  entirely 
satisfactory  in  its  resistance  to  exposure  to  salt  water,  though  in  part 
this  is  often  due  to  the  use  of  porous  mixtures  which  permit  access  of  the 
water  to  the  interior  of  the  block  of  cement  or  concrete.  The  use  of 
richer  mixtures,  or  at  least  of  a  richer  mixture  for  the  surface  of  the 
block,  will  do  away  with  many  of  tlj£  difficulties  encountered.  Aside 
from  this,  two  methods  of  improvements  have  been  advocated.  One 
is  to  make  the  cement  more  resistant  of  itself  by  making  it  of  such 
a  chemical  composition  as  will  show  the  maximum  resistance  to  the 
effects  of  salt  water.  This  is  the  method  of  Le  Chatelier,  discussed 
below.  The  second  method  is,  to  add  to  the  cement,  trass,  slag,  or 
other  puzzolanic  material,  in  order  that  the  lime  liberated  by  the  cement 
during  hardening  may  be  taken  up  and  combined  with  the  trass. 

Le  Chatelier  considers  that  the  aluminous  compounds  present  in 
Portland  cement  are  the  direct  cause  of  its  destruction  by  sea-water. 
His  theory,  to  account  for  this  disintegration,  is  as  follows :  Free  lime, 
liberated  during  the  hardening  of  the  cement,  reacts  with  the  mag- 
nesium sulphate  always  present  in  sea-water,  to  form  calcium  sulphate. 
This  in  turn  reacts  with  the  calcium  aluminate  of  the  cement  to  form 
a  sulphaluminate  of  lime,  which  swells  considerably  on  hydration  and 
thus  disintegrates  the  cement  mass.  The  extent  of  the  disintegration 
varies  directly  with  the  percentage  of  alumina  present  in  the  cement. 
Cements  containing  1  or  2  per  cent  of  alumina  are,  for  example,  practi- 
cally unaffected  by  sea-water;  while  in  cement  containing  as  high  as  7 
or  8  per  cent  of  alumina  the  swelling  and  consequent  disintegration 
are  very  rapid. 

If  the  alumina  of  a  cement  be  replaced  by  an  oxide  not  reacting 
with  calcium  sulphate,  the  stability  of  the  cement  in  sea-water  is 
greatly  improved.  Le  Chatelier  has  demonstrated  this  by  preparing 
cements  in  which  the  alumina  was  replaced  by  oxides  of  iron,  chro- 
mium, cobalt,  etc.  All  of  these  were  more  resistant  than  an  alumina 
cement  to  the  disintegrating  effect  of  lime  sulphate.  The  best  effects 
were  obtained  when  iron  oxide  was  used,  a  cement  corresponding  in 
composition  to  5SiO2,Fe203,17CaO  being  found  to  be  not  only  stable  in 
presence  of  sea-water,  but  to  possess  excellent  mechanical  properties. 

DevaPs  researches  *  on  the"  effect  of  direct  addition  of  calcium  sul- 
phate to  various  cements  confirm  the  above  theory.  Each  of  the  finely 
ground  cements  tested  was  completely  hydrated  by  mixing  with  50  per 
cent  of  water,  and  storing  the  mixture  under  water  for  three  months  out  of 

*  Abstract  in  Journ.  Soc.  Chem.  Industry,  vol.  21,  p.  971-972. 


PHYSICAL  PROPERTIES  OF  PORTLAND  CEMENT. 


603 


contact  with  carbon  dioxide.  The  mass  was  then -dried,  reground,  mixed 
with  half  its  weight  of  calcium  sulphate  and  33  per  cent  of  water,  and 
made  up  into  rods,  which  were  kept  moist  and  protected  from  carbon 
dioxide  by  storage  on  moistened  filter  paper  under  a  glass  bell.  At 
the  end  of  three  weeks  the  increase  in  length  of  the  rods  was  measured, 
with  the  following  results: 

TABLE  233. 
EFFECT  OF  ALUMINA. 


Type  of  Cement. 

Per  Cent  of 
Alumina  in  the 
Cement. 

Per  Cent  of 
Elongation 
of  the  Rods. 

Slag  cement  (Vitry) 

15  5 

27 

Slag  cement  (Champignolles) 

14  5 

16 

Grappier  cement  (Besses)     .... 

7  5 

14 

Portland  cement               

6  2 

12 

Hydraulic  lime  (Besses)    

4  7 

4 

It  will  be  noted  that  the  percentage  of  elongation  of  the  rods,  varied 
directly  with  the  percentage  of  alumina  in  the  cements  tested,  proving 
conclusively  that  the  swelling  was  due  to  the  action  of  the  calcium 
sulphaluminate  formed  during  the  operation. 


STANDARD  METHODS  OF  TESTING,  AM.  SOC.  C.E. 

A  Committee  appointed  by  the  American  Society  of  Civil  Engineers 
to  examine  methods  of  making  cement  tests,  offered  a  progress  report 
early  in  1903,  and  a  brief  supplementary  report  in  1904.  These  reports 
have  been  combined  and  are  presented  below. 

Standard  Methods  of  Cement  Testing. 

SAMPLING. 

1.  Selection  of  sample. — The  selection  of  the  sample  for  testing  is 
a  detail  that  must  be  left  to  the  discretion  of  the  engineer;  the  number 
and  the  quantity  to  be  taken  from  each  package  will  depend  largely 
on  the  importance  of  the  work,  the  number  of  tests  to  be  made  and  the 
facilities  for  making  them. 

2.  The  sample  shall  be  a  fair  average  of  the  contents  of  the  packing; 
it  is  recommended  that,  where  conditions  permit,  one  barrel  in  every 
ten.  be  sampled. 

3.  All  samples  should  be  passed  through  a  sieve  having  20  meshes 
per  linear  inch  in  order  to  break  up  lumps  and  remove  foreign  material; 


604  CEMENTS,  LIMES,  AND  PLASTERS. 

this  is  also  a  very  effective  method  for  mixing  them  together  in  order 
to  obtain  an  average.  For  determining  the  characteristics  of  a  ship- 
ment of  cement,  the  individual  samples  may  be  mixed  and  the  average 
tested;  where  time  will  permit,  however,  it  is  recommended  that  they 
be  tested  separately. 

4.  Method  of  sampling. — Cement  inj^arrels  should  be  sampled  through 
a  hole  made  in  the  center  of  one  of  the  staves,  midway  between  the 
heads,  or  in  the  head,  by  means  of  an  auger  or  a  sampling  iron  similar 
to  that  used  by  sugar  inspectors.     If  in  bags,  it  should  be  taken  from 
surface  to   center. 

CHEMICAL   ANALYSIS. 

5.  Significance. — Chemical    analysis    may    render    valuable    service 
in  the  detection  of  adulteration  of  cement  with  considerable  amounts 
of  inert  material,  such  as  slag  or  ground  limestone.     It  is  of  use,  also, 
in  determining  whether  certain  constituents,  believed  to  be  harmful 
when  in  excess  of  a  certain  percentage,  as  magnesia  and  sulphuric  anhy- 
dride, are  present  in  inadmissible  proportions.     While  not  recommending 
a  definite  limit  for  these  impurities,  the  committee  would  suggest  that 
the  most  recent  and  reliable  evidence  appears  to  indicate  that  mag- 
nesia to  the  amount  of  5  per  cent,  and  sulphuric  anhydride  to  the  amount 
of  1.75  per  cent,  may  safely  be  considered  harmless. 

6.  The  determination  of  the  principle  constituents  of  cement — silica, 
alumina,  iron  oxide  and  lime — is  not  conclusive  as  an  indication  of  quality. 
Faulty   character   of   cement   results   more   frequently   from   imperfect 
preparation  of  the  raw  material  or  defective  burning  than  from  incor- 
rect proportions  of  the  constituents.     Cement  made  from  very  finely 
ground  material,  and  thoroughly  burned,  may  contain  much  more  lime 
than  the  amount  usually  present  and  still  be  perfectly  sound.     On  the 
other  hand,  cements  low  in  lime  may,  on  account  of  careless  preparation 
of  the  raw  material,  be  of  dangerous  character.     Further,  the  ash  of 
the  fuel  used  in  burning  may  so  greatly  modify  the  composition  of  the 
product  as  largely  to  destroy  the  significance  of  the  results  of  analysis'. 

7.  Method. — As  a  method  to  be  followed  for  the  analysis  of  cement, 
that  proposed  by  the  Committee  on  Uniformity  in  the  analysis  of  Ma- 
terials for  the  Portland  Cement  Industry,  of  the  New  York  Section  of 
the  Society  for  Chemical  Industry,  and  published  in  the  Journal  of  the 
Society  for  January  15,  1902,  is  recommended. 


PHYSICAL  PROPERTIES  OF  PORTLAND  CEMENT.  605 


SPECIFIC    GRAVITY. 

8.  Significance, — The  specific  gravity  of  cement  is  lowered  by  under- 
burning,  adulteration  and  hydration,  but  the  adulteration  must  be  in 
considerable  quantity  to  affect  the  results  appreciably. 

9.  Inasmuch  as  the  differences  in  specific  gravity  are  usually  very 
small,  great  care  must  be  exercised  in  making  the  determination. 

10.  When  properly  made,  this  test  affords  a  quick  check  for  under- 
burning  or  adulteration. 

11.  Apparatus  and  method. — The  determination  of  specific  gravity 
is  most  conveniently  made  with  Le  Chatelier's  apparatus.     This  con- 
sists of  a  flash  of  120  cu.  cm.  (7.32  cu.  inches)  capacity,  the  neck  of  which 
is  about  20  cm.  (7.87  inches)  long;  in  the  middle  of  this  neck  is  a  bulb, 
above  and  beolw  which  are  two  marks ;  the  volume  between  these  marks 
is  20  cu.  cm.  (1.22  cu.  inches).     The  neck  has  a  diameter  of  about  9  mm. 
(0.35  inch),  and  is  graduated  into   tenths   of  cubic   centimeters  above 
the    bulb. 

12.  Benzine   (62°  Baume  naphtha),   or  kerosene  free  from  water, 
should  be  used  in  making  the  determination. 

13.  The  specific  gravity  can  be  determined  in  two  ways: 

(1)  The  flask  is  filled  with  either  of  these  liquids  to  the  lower  mark 
and  64  grs.  (2.25  ozs.)  of  powder,  previously  dried  at  100°  C.  (212°  F.) 
and  cooled  to  the  temperature  of  this  liquid,  is  gradually  introduced 
through  the  funnel  (the  stem  of  which  extends  into  the  flask  to  the  top 
of  the  bulb),  until  the  upper  mark  is  reached.  The  difference  in  weight 
between  the  cement  remaining  and  the  original  quantity  (64  grs.)  is 
the  weight  which  has  displaced  20  cu.  cm. 

14.  (2)  The  whole  quantity  of  the  powder  is  introduced,  and  the 
level  of  the  liquid  rises  to  some  division  of  the  graduated  neck.     This 
reading  plus  20  cu.  cm.  is  the  volume  displaced  by  64  gr.  of  the  powder. 

15.  The  specific  gravity  is  then  obtained  from  the  formula: 

0       .  „  .         Weight  of  cement 

Specific  gravity  =  fr7-J         ,  Tr  , . 

Displaced  Volume 

16.  The  flask,  during  the  operation,  is  kept  immersed  in  water  in 
a  jar,  in  order  to  avoid  variations  in  the  temperature  of  the  liquid.    The 
results  should  agree  within  0.01. 

17.  A  convenient  method  for  cleaning  the  apparatus  is  as  follows: 
The  flask  is  inverted  over  a  large  vessel,  preferably  a  glass  jar,  and  shaken 
vertically  until  the  liquid  starts  to  flow  freely,  it  is  then  held  still  in 
a  vertical  position  until  empty,  the  remaining  traces  of  cement  can  be 


606  CEMENTS,  LIMES,  AND   PLASTERS. 

removed  in  a  similar  manner  by  pouring  into  the  flask  a  small  quantity 
of  clean  liquid  and  repeating  the  operation. 

18.  More    accurate    determinations    may  be  made  with    the    pic- 
nometer. 

FINENESS. 

19.  Significance. — It  is  generally  accepted  that  the  coarser  particles 
in  cement  are  practically  inert,  and  it  is  only  the  extremely  fine  powder 
that  possesses  adhesive  or  cementing  qualities.     The  more  finely  cement 
is  pulverized,  all  other  conditions  being  the  same,  thfe  more  sand  it  will 
carry  and  produce  a  mortar  of  a  given  strength. 

20.  The  degree  of  final  pulverization  which  the  cement  receives  at 
the  place  of  manufacture  is  ascertained  by  measuring  the  residue  re- 
tained on  certain  sieves.     Those  known  as  the  No.  100  and  No.  200 
sieves  are  recommended  for  this  purpose. 

21.  Apparatus. — The  sieves  should  be  circular,  about  20  cm.  (7.87 
inches)  in  diameter,  6  cm.  (2.36  inches)  high,  and  provided  with  a  pan, 
5  cm.  (1.97  inches)  deep,  and  a  cover. 

22.  The  wire  cloth  should  be  woven  (not  twilled)  from  brass  wire 
having  the  following  diameters: 

No.  100,  0.0045  inch;   No.  200,  0.0024  inch. 

23.  This  cloth  should  be  mounted  on  the  frames  without  distortion; 
the  mesh  should  be  regular  in  spacing,  and  be  within  the  following  limits : 

No.  100,    96  to  100  meshes  to  the  linear  inch. 
No.  200,  188  to  200       "        "      " 

24.  Fifty  grams  (1.76  oz.)  or  100  gr.  (3.52  oz.)  should  be  used  for 
the  test,  and  dried  at  a  temperature  of  100°  C.  (212°  F.)  prior  to  sieving. 

25.  Method. — The  Committee,  after  careful  investigation,  has  reached 
the  conclusion  that  mechanical  sieving  is  not  as  practicable  or  efficient 
as  hand-work,  and,  therefore,  recommends  the  following  method: 

26.  The  thoroughly  dried  and  coarsely  screened  sample  is  weighed 
and  placed  on  the  No.  200  sieve,  which,  with  pan  and  cover  attached, 
is  held  in  one  hand  in  a  slightly  inclined  position,  and  moved  forward 
and  backward,  at  the  same  time  striking  the  side  gently  with  the  palm 
of  the  other  hand,  at  the  rate  of  about  200  strokes  per  minute.     The 
operation  is  continued  until  not  more  than  one  tenth  of  1   per  cent 
passes  through  after  one  minute  of  continuous  sieving.     The  residue  is 
weighed,  then  placed  on  the  No.  100  sieve  and  the  operation  repeated. 


PHYSICAL  PROPERTIES  OF  PORTLAND   CEMENT.  607 

The  work  may  be  expedited  by  placing  in  the  sieve  a  small  quantity 
of  large  shot.  The  results  should  be  reported  to  the  nearest  tenth  of 
1  per  cent. 

NORMAL   CONSISTENCY. 

27.  Significance. — The  use  of  a  proper  percentage  of  water  in  making 
the  pastes  *  from  which  pats,  tests  of  setting  and  briquettes  are  made, 
is  exceedingly  important,  and  affects  vitally  the  results  obtained. 

28.  The  determination  consists  in  measuring  the  amount  of  water 
required  to  reduce  the  cement  to  a  given  state  of  plasticity,  or  to  what 
is  usually  designated  the  normal  consistency. 

29.  Various  methods  have  been  proposed  for  making  this  determina- 
tion, none  of  which  has  been  found  entirely  satisfactory.      The  Com- 
mittee recommends  the  following: 

30.  Method.     Vicat  needle  apparatus. — This  consists  of  a  frame  bear- 
ing a  movable  rod,  with  the  cap  at  one  end,  and  at  the  other  end  the 
cylinder,  1  cm.  (0.39  inch)  in  diameter,  the  cap,  rod,  and  cylinder  weigh- 
ing 300  gr.   (10.58  oz.).     The  rod,  which  can  be  held  in  any    desired 
position  by  a  screw,  carries  an  indicator,  which  moves  over  a  scale 
(graduated  to  centimeters)  attached  to  the  frame.     The  paste  is  held 
by  a  conical,  hard-rubber  ring,  7  cm.  (2.76  inches)  in  diameter  at  the 
base,  4  cm.  (1.57  inches)  high,  resting  on  a  glass  plate  about  10  cm. 
(3.94  inches)  square. 

31.  In  making  the  determination,  the  same  quantity  of  cement  as 
will  be  subsequently  used  for  each  batch  in  making  the  briquettes  (but 
not  less  than  500  gr.)  is  kneaded  into  a  paste,  as  described  in  Para- 
graph 58,  and  quickly  formed  into  a  ball  with  the  hands,  completing 
the  operation  by  tossing  it  six  times  from  one  hand  to  the  other,  main- 
tained 6  inches  apart;    the  ball  is  then  pressed  into   the  rubber  ring 
through  the  larger  opening,  smoothed  off,  and  placed  on  a  glass  plate 
(on  its  large  end)  and  the  smaller  end  smoothed  off  with  a  trowel;  the 
paste,  confined  in  the  ring,  resting  on  the  plate,  is  placed  under  the  rod 
bearing  the  cylinder,  which  is  brought  in  contact  with  the  surface  and 
quickly  released. 

32.  The  paste  is  of  normal  consistency  when  the  cylinder  penetrates 
to  a  point  in  the  mass  10  mm.  (0.39  inch)  below  the  top  of  the  ring. 
Great  care  must  be  taken  to  fill  the  ring  exactly  to  the  top. 


*The  term  "paste"  is  used  in  this  report  to  designate  a  mixture  of  cement 
and  water,  and  the  word  "mortar"  a  mixture  of  cement,  sand,  and  water. 


CEMENTS,  LIMES,  AND   PLASTERS. 

33.  The  trial  pastes  are  made  with  varying  percentages  of  water 
until  the  correct  consistency  is  obtained. 

34.  The  Committee  has  recommended,  as  normal,  a  paste,  the  con- 
sistency of  which  is  rather  wet,  because  it  believes  that  variations  in 
the  amount  of  compression  to  which  the  briquette  is  subjected  in  mould- 
ing are  likely  to  be  less  with  such  a  paste. 

35.  Having   determined  .in  this  manner  the  proper  percentage   of 
water  required  to  produce  a  neat  paste'  of  normal  consistency,  the  proper 
percentage  required  for  the  sand  mortars  is  obtained  from  an  empirical 
formula. 

36.  The  Committee  hopes  to  devise  such  a  formula.     The  subject 
proves  to  be  a  very  difficult  one,  and,  although  the  Committee  has 
given  it  much  study,  it  is  not  yet  prepared  to  make  a  definite  recom- 
mendation. 

TIME   OF  SETTING. 

37.  Significance. — The  object  of  this  test  is  to  determine  the  time 
which  elapses  from  the  moment  water  is  added  until  the  paste  ceases 
to  be  fluid  and  plastic   (called  the   "initial  set"),  and  abo  the  time 
required   for  it   to   acquire   a   certain   degree   of  hardness    (called   the 
"final"  or  "hard  set").     The  former  of  these  is  the  more  important, 
since,  with  the  commencement  of  setting,  the  process  of  crystallization 
or  hardening  is  said  to  begin.     As  a  disturbance  of  this  process  may 
produce  a  loss  of  strength,  it  is  desirable  to  complete  the  operation  of 
mixing  and  moulding  or  incorporating  the  mortar  into  the  work  before 
the  cement  begins  to  set. 

38.  It  is  usual  to  measure  arbitrarily  the  beginning  and  end  of  the 
setting  by  the  penetration  of  weighted  wires  of  given  diameters. 

39.  Method. — For  this  purpose  the  Vicat  needle,  which  has  already 
been  described  in  Paragraph  30,  should  be  used. 

40.  In  making  the  test,  a  paste  of  normal  consistency  is  moulded 
and  placed  under  the  rod,  as  described  in  Paragraph  31;   this  rod,  bear- 
ing the  cap  at  one  end  and  the  needle,  1  mm.  (0.039  inch)  in  diameter, 
at  the  other,  weighing  300  gr.  (10.58  oz.).     The  needle  is  then  carefully 
brought  in  contact  with  the  surface  of  the  paste  and  quickly  released. 

41.  The  setting  is  said  to  have  commenced  when  the  needle  ceases 
to  pass  a  point  5  mm.  (0.20  inch)  above  the  upper  surface  of  the  glass 
plate,  and  is  said  to  have  terminated  the  moment  the  needle  does  not 
sink  visibly  into  the  mass. 

42.  The  test  pieces  should  be  stored  in  moist  air  during  the  test; 
this  is  accomplished  by  placing  them  on  a  rack  over  water  contained 


PHYSICAL  PROPERTIES  OF  PORTLAND  CEMENT.  609 

in  a  pan  and  covered  with  a  damp  cloth,  the  cloth  to  be  kept  away 
from  them  by  means  of  a  wire  screen;  or  they  may  be  stored  in  a  moist 
box  or  closet. 

43.  Care  should  be  taken  to  keep  the  needle  clean,  as  the  collection 
of  cement  on  the  sides  of  the  needle  retards  the  penetration,  while  cement 
on  the  point  reduces  the  area  and  tends  to  increase  the  penetration. 

44.  The  determination  of  the  time  of  setting  is  only  approximate, 
being  materially   affected  by   the   temperatures   of  the  mixing   water, 
the  temperature  and  humidity  of  the  air  during  the  test,  the  percentage 
of  water  used,  and  the  amount  of  moulding  the  paste  receives. 

STANDARD    SAND. 

45.  The  Committee  recognizes  the  grave  objections  to  the  standard 
quartz  now  generally  used,  e3pecially  on  account  of  its  high  percentage 
of  voido,  the  difficulty  of  compacting  in  the  moulds,  and  its  lack  of 
uniformity;   it  has  spent  much  time  in  investigating  the  various  natural 
sando  which  appeared  to  be  available  and  suitable  for  use. 

46.  For  the  present,  the  Committee  recommends  the  natural  sand 
from  Ottawa,  111.,  screened  to  pass  a  sieve  having  20  meshes  per  linear 
inch  and  retained  on  a  sieve  having  30  meshes  per  linear  inch;    the 
wires  to  have  diameters  of  0.0165  and  0.0112  inch,  respectively,  i.e., 
half  the  width  of  the  opening  in  each  case.     Sand  having  passed  the 
No.  20  sieve  shall  be  considered  standard  when  not  more  than  1  per  cent 
passes  a  No.  30  sieve  after  one  minute  continuous  sifting  of  a  500  gr. 
sample. 

47.  The  Sandusky  Portland  Cement  Company,  of  Sandusky,  Ohio, 
has  agreed  to  undertake  the  preparation  of  this  sand,  and  to  furnish 
it  at  a  price  only  sufficient  to  cover  the  actual  cost  of  preparation. 

\ 

FORM   OF   BRIQUETTE. 

48.  While   the   form   of   the   briquette   recommended   by   a   former 
Committee  of  the  Society  is  not  wholly  satisfactory  this   Committee 
is  not  prepared  to  suggest  any  change,  other  than  rounding  off  of  the 
corners  by  curves  of  J-inch  radius. 

MOULDS. 

49.  The  moulds  should  be  made  of  brass,  bronze,  or  some  equally 
non-corrodible  material,  having  sufficient  metal  in  the  sides  to  pre- 
vent spreading  during  moulding 


610  CEMENTS,  LIMES,  AND  PLASTERS. 

50.  Gang  moulds,  which  permit  moulding  a  number  of  briquettes 
at  one  time,  are  preferred  by  many  to  single  moulds;   since  the  greater 
quantity  of  mortar  that  can  be  mixed  tends  to  produce  greater  uni- 
formity in  the  results. 

51.  The  moulds  should  be  wiped  with  an  oily  cloth  before  using. 

MIXING. 

52.  All  proportions  should  be  stated  by  weight;    the. quantity  of 
water  to  be  used  should  be  stated  as  a  percentage  p_f  the  dry  material. 

53.  The  metric  system  is  recommended  because  of  the  convenient 
relation  of  the  gram  and  the  cubic  centimeter. 

54.  The  temperature  of  the  room  and  the  mixing  water  should  be 
as  near  21°  C.   (70°  F.)  as  it  is  practicable  to  maintain  it. 

55.  The  sand  and  cement   should   be   thoroughly  mixed   dry.     The 
mixing  should  be  done  on  some  non-absorbing  surface,  preferably  plate 
glass.     If  the  mixing  must  be  done  on  "an  absorbing  surface  it  should 
be  thoroughly  dampened  prior  to  use. 

56.  The  quantity  of  material  to  be  mixed  at  one  time  depends  on 
the  number   of   test  pieces  to  be  made;    about   1000  gr.    (35.28  oz.) 
makes  a  convenient  quantity  to  mix,  especially  by  hand  methods. 

57.  The  Committee,  after  investigation  of  the  various  mechanical 
mixing-machines,  has  decided  not  to  recommend  any  machine  that  has 
thus  far  been  devised,  for  the  following  reasons: 

(1)  The  tendency  of  most  cement  is  to  "ball  up"  in  the  machine 
thereby  preventing  the  working  of  it  into  a  homogeneous  paste;  (2) 
there  are  no  means  of  ascertaining  when  the  mixing  is  complete  with- 
out stopping  the  machine,  and  (3)  the  difficulty  of  keeping  the  machine 
clean. 

58.  Method. — The  material  is  weighed  and  placed  on  the  mixing 
table,  and  a  crater  formed  in  the  center,  into  which  the  proper  per- 
centage of  clean  water  is  poured;    the  material  on  the  outer  edge  is 
turned  into  the  crater  by  the  aid  of  a  trowel.     As  soon  as  the  water  has 
been  absorbed,  which  should  not  require  more  than  one  minute,  the 
operation   is   completed  by  vigorously   kneading  with   the   hands   for 
an  additional   1J  minutes,  the  process  being  similar  to  that  used  in 
kneading    dough.     A   sand-glass    affords    a    convenient   guide   for   the 
time  of  kneading.     During  the  operation  of  mixing,  the  hands  should 
be  protected  by  gloves,  preferably  of  rubber. 


PHYSICAL  PROPERTIES  OF  PORTLAND  CEMENT.  611 


MOULDING. 

59.  Having  worked  the  paste  or  mortar  to  the  proper  consistency, 
it  is  at  once  placed  in  the  moulds  by  hand. 

60.  The  Committee  has   been    unable  to  secure  satisfactory  results 
with  the  present  moulding-machines;   the  operation  of  machine  mould- 
ing is  very  slow,  and  the  present  types  permit  of  moulding  but  one 
briquette  at  a  time,  and  are  not  practicable  with  the  pastes  or  mortars 
herein  recommended. 

61.  Method. — The   moulds   should   be   filled   at   once,   the   material 
pressed  in  firmly  with  the  fingers  and  smoothed  off  with  a  trowel  with- 
out ramming;  the  material  should  be  heaped  up  on  the  upper  surface 
of  the  mould,  and,  in  smoothing  off,  the  trowel  should  be  drawn  over 
the  mould  in  such  a  manner  as  to  exert  a  moderate  pressure  on  the 
excess  material.     The  mould  should  be  turned  over  and  the  operation 
repeated. 

62.  A    check  upon  the  uniformity  of  the  mixing  and  moulding  is 
afforded  by  weighing  the  briquettes  just  prior  to  immersion,  or  upon 
removal  from  the  moist  closet.     Briquettes  which  vary  in  weight  more 
than  3  per  cent  from  the  average  should  not  be  tested. 

STORAGE    OF  THE   TEST    PIECES. 

63.  During    the    first  twenty-four    hours    after    moulding,  the  test 
pieces  should  be  kept  in  moist  air  to  prevent  them  from  drying  out. 

64.  A  moist  closet  or  chamber  is  so  easily  devised  that  the  use  of 
the  damp  cloth  should  be  abandoned  if  possible,,      Covering  the  test 
pieces  with  a  damp  cloth  is  objectionable,  as  commonly  used,  because 
the  cloth  may  dry  out  unequally,  and,  in  consequence,  all  the  test  pieces 
are  not  maintained  under  the  same  condition.     Where  a  moist  closet 
is  not  available,  a  cloth  may  be  used  and  kept  uniformly  wet  by  immer- 
sing the  ends  in  water.     It  should  be  kept  from  direct  contact  with  the 
test    pieces    by  means  of  a  wire  screen  or  some  similar  arrangement. 

65.  A  moist  closet  consists  of  a  soapstone  or  slate  box;   or  a  metal- 
lined  wooden  box,  the  metal  lining  being  covered  with  felt  and  this  felt 
kept  wet.     The  bottom  of  the  box  is  so  constructed  as  to  hold  water, 
and  the  sides  are  provided  with  cleats  for  holding  glass  shelves  on  which 
to  place  the  briquettes.     Care  should  be  taken  to  keep  the  air  in  the 
closet  uniformly  moist. 

66.  After  twenty-four  hours  in  moist  air,  the  test  pieces  for  longer 
periods  should  be  immersed  in  water  maintained  as  near  21°  C.  (70°  F.) 


612  CEMENTS,  LIMES,  AND  PLASTERS. 

as  practicable;    they  may  be  stored  in  tanks  or  pans,  which  should 
be  of  non-corrodible  material. 


TENSILE    STRENGTH. 

67.  The  tests  may  be  made  on  •  any  standard  machine.     A  solid 
metal  clip  is  recommended.    This  clip  is  to  be  used  without  cushion- 
ing at  the  points  of  contact  with  the  test  specimen.     The  bearing  at 
each  point  of  contact  should  be  J  inch  wide,  and  tfee  distance  between 
the  centers  of  contact  on  the  same  clips  should  be  1J  inches. 

68.  Test  pieces  should  be  broken  as  soon  as  they  are  removed  from 
the  water.     Care  should  be  observed  in  centering  the  briquette  in  the 
testing-machine,  as  cross-strains,  produced  by  improper  centering,  tend 
to  lower  the  breaking  strength.     The  load  should  not  be  applied  too 
suddenly,   as  it  may  produce  vibration,  the  shock  from  which  often 
breaks   the   briquette  before  the  ultimate  strength  is   reached.     Care 
must  be  taken  that  the  clips  and  the  sides  of  the  briquettes  be  clean 
and  free  from  grains  of  sand  or  dirt,  which  would  prevent  a  good  bear- 
ing.    The  load  should  be  applied  at  the  rate  of  600  Ibs.  per  minute. 
The  average  of  the  briquettes  of  each  sample  tested  should  be  taken  as 
the  test,  excluding  any  results  which  are  manifestly  faulty. 


CONSTANCY   OF   VOLUME. 

69.  Significance. — The   object   is   to   develop   those  qualities  which 
tend  to  destroy  the  strength   and  durability  of  a   cement.     As  it  is 
highly  essential  to  determine  such  qualities  at  once,  tests  of  this  char- 
acter are  for  the  most  part  made  in  a  very  short  time,  and  are  known, 
therefore,  as  accelerated  tests.     Failure  is  revealed  by  cracking,  check- 
ing, swelling,  or  disintegration,  or  all  of  these  phenomena.     A  cement 
which  remains  perfectly  sound  is  said  to  be  of  constant  volume. 

70.  Methods. — Tests  for  constancy  of  volume  are  divided  into  two 
classes:    (1)  normal  tests,  or  those  made  in  either  air  or  water  main- 
tained at  about  21°  C.  (70°  F.),  and  (2)  accelerated  tests,  or  those  made 
in  air,  steam,  or  water  at  a  temperature  of  45°  C.  (115°  F.)  and  upward. 
The  test  pieces  should  be  allowed  to  remain  twenty-four  hours  in  moist 
air  before  immersion  in  water  or  steam,  or  preservation  in  air. 

71.  For  these  tests,  pats,  about  7J  cm.  (2.95  inches)  in  diameter,  1} 
cm.  (0.49  inch)  thick  at  the  center,  and  tapering  to  a  thin  edge,  should 
be  made,  upon  a  clean  glass  plate  [about  10  cm.  (3.94  inches)  square], 
from  cement  paste  of  normal  consistency. 


PHYSICAL  PROPERTIES  OF  PORTLAND  CEMENT.  613 

72.  Normal  test. — A  pat  is  immersed  in  water  maintained  as  near 
210°  C.   (70°  F.)  as  possible  for  twenty-eight  days,  and   observed  at 
intervals;  the  pat  should  remain  firm  and  hard  and  show  no  signs  of 
cracking,  distortion,    or   disintegration.     A   similar   pat   is   maintained 
in  air  at  ordinary  temperature  and  observed  at  intervals. 

73.  Accelerated  test. — A  pat  is  exposed  in  any  convenient  way  in  an 
atmosphere .  of  steam,  above  boiling  water,  in  a  loosely  closed  vessel, 
for  three  hours. 

74.  To  pass  these  tests  satisfactorily,  the  pats  should  remain  firm 
and  hard,  and  show  no  signs  of  cracking,  distortion,  or  disintegration. 

75.  Should  the  pat  leave  the  plate,  distortion  may  be  detected  best 
with  a  straight-edge  applied  to  the  surface  which  was  in  contact  with 
the  plate. 

76.  In  the  present  state  of  our  knowledge  it  cannot  be  said  that 
cement  should  necessarily  be  condemned  simply  for  failure  to  pass  the 
accelerated  tests,  nor  can  a  cement  be  considered  entirely  satisfactory 
simply  because  it  has  passed  these  tests. 


CHAPTER  XL. 
SPECIFICATIONS  FOR  PORTLAND  CEMENT. 

VARIOUS  specifications  for  Portland  cement  have  been  collected  for 
insertion  in  the  present  chapter.  These  are  of  interest  partly  for  com- 
parison and  partly  to  show  the  growth  of  intelligent  treatment  of  this 
subject.  The  specifications  of  the  American  Society  for  Testing  Ma- 
terials will,  it  is  probable,  become  the  standard  in  this  country. 

New  York  State  Canals,  1896. 

The  mortar  and  grout  will  be  made  of  the  best  quality  of  Portland 
or  natural  hydraulic  cement,  as  may  be  directed,  and  clean,  sharp  sand, 
in  such  proportions  and  made  and  used  in  such  manner  as  may  be  re- 
quired by  the  engineer. 

No  cement  shall  be  used  in  any  part  of  the  masonry  until  the  State 
engineer  shall  have  examined,  tried,  and  approved  the  same.  It  must 
be  delivered  in  tight  casks  or  bags,  as  the  division  or  resident  engineer 
may  direct,  and  thereafter  be  properly  protected  from  the  weather. 

The  engineer  to  direct  in  what  manner  the  sand  shall  be  screened 
and  worked,  and  washed,  if  necessary.  When  considered  necessary 
by  the  engineer,  salt  shall  be  used  with  the  mortar  in  such  manner  and 
proportions  as  he  may  direct. 

Special  directions  shall  be  given  by  the  engineer  as  to  the  delivery 
of  cement  and  as  to  the  time  and  facilities  required  for  testing  it  previous 
to  its  use  in  the  work.  No  cement  will  be  used  except  in  compliance 
with  these  directions.  All  facilities  required  by  the  engineer  for  securing 
tests  must  be  afforded  by  the  contractor.  All  cement  must  be  stored 
in  substantial  water-proof  structures  from  the  time  of  delivery  till  used. 

All  cement  offered  for  use  in  any  work  will  be  sampled  by  an  agent 
of  the  State  Engineer's  Department.  Samples  will  be  collected  immedi- 
ately on  delivery  of  cement  at  site  of  work,  and  contractors  will  promptly 
notify  the  engineer  of  the  receipt  of  cement,  in  order  that  no  delay  may 
be  had  in  the  sampling  thereof.  All  samples  will  be  forwarded  to  the 

614 


SPECIFICATIONS  FOR  PORTLAND  CEMENT.  615 

cement-testing  office  in  Albany,  and  will  be  subjected  to  the  following 
tests,  and  any  cement  failing  on  either  of  them  will  be  rejected,  though 
the  further  right  is  reserved  to  reject  any  and  all  cements  the  qualities 
of  which  have  not  become  well  known  through  prior  use  in  State  work 
or  elsewhere. 

Portland  cement  must  be  of  the  best  quality  and  of  such  fineness 
that  95  per  cent  of  the  cement  will  pass  through  a  sieve  of  2500  meshes 
to  the  square  inch,  and  90  per  cent  through  a  sieve  of  10,000  meshes 
per  square  inch.  Portland  cement  when  mixed  neat  and  exposed  one 
day  in  air  and  six  days  in  water  shall  withstand  a  tensile  strain  of 
not  less  than  400  Ibs.  to  the  square  inch,  and  when  mixed  in  the  ratio  of 
3  Ibs.  clean,  sharp  sand  to  1  Ib.  of  cement  and  exposed  one  day  in  air 
and  six  days  in  water,  it  shall  withstand  a  tensile  strain  of  not  less  than 
125  Ibs.  per  square  inch. 

Rapid-transit  Subway,  New  York  City,  1900-1901. 

Fineness. — Ninety-eight  per  cent  shall  pass  a  No.  50  sieve  and  90 
per  cent  a  No.  100  sieve. 

Tensile  strength. — At  the  end  of  one  day  in  water  after  hard  set, 
150  Ibs.  neat;  at  the  end  of  seven  days,  one  day  in  air,  six  days  in 
water,  400  Ibs.  neat;  at  the  end  of  twenty-eight  days,  one  day  in  air, 
twenty-seven  days  in  water,  500  Ibs.  neat.  When  mixed  2  to  1  with 
quartz  sand:  At  the  end  of  seven  days,  one  day  in  air,  six  days  in  water, 
200  Ibs.;  at  the  end  of  twenty-eight  days,  one  day  in  air,  twenty-seven 
days  in  water,  300  Ibs. 

Chemical  analyses. — Chemical  analyses  will  be  made  from  time 
to  time,  and  cement  furnished  must  show  a  reasonably  uniform  com- 
position. 

Soundness. — Tests  for  checking  and  cracking  and  for  color  will  be 
made  by  molding,  on  plates  of  glass,  cakes  of  neat  cement  about  3  inches 
in  diameter,  \  inch  thick  in  the  center,  and  with  very  thin  edges.  One 
of  these  cakes  when  set  per  ectly  hard  shall  be  put  in  water  and  examined 
for  distortion  or  cracks,  and  one  shall  be  kept  in  air  and  examined  for 
color,  distortion,  and  cracks.  Another  cake  shall  be  allowed  to  set 
in  steam  for  twenty-four  hours  and  then  put  in  boiling  water  for 
twenty-four  hours.  Another  cake  shall  be  allowed  to  set  hard  in  dry 
air  for  twenty-four  hours  and  then  put  in  boiling  water  for  twenty-four 
hours.  Such  cakes  should  at  the  end  of  the  tests  still  adhere  to  the 
glass  and  show  neither  cracks  nor  distortion.  A  briquette,  in  like  man- 
ner, should  be  allowed  to  set  hard  in  dry  air  for  twenty-four  hours, 


€16  CEMENTS,  LIMES,  AND  PLASTERS. 

then  boiled  for  twenty-four  hours,  be  kept  for  five  days  in  water,  and 
show  350  Ibs.  tensile  strength. 


Department  of  Bridges^  New  York  City,  1901. 

(106)  That  all  cement  used  on  this  work  must  be  the  best  quality 
•of  imported  or  American  Portland  cement,  manufactured  by  works 
of  established  reputation  for  furnishing  a  high-grade  and  uniform  product. 
Cement  must  show  a  chemical  analysis  satisfactory  to  the  engineer. 

(107)  That  briquettes  of  neat  cement  exposed  to  air  for  twenty- 
four  hours  and  then  immersed  in  water  for  six  days  must  have  a  tensile 
strength  of  at  least  400  Ibs.  per  square  inch. 

(108)  That  briquettes  of  mortar  mixed  in  proportion  of  one  part 
of  cement  to  two  and  one  half  parts  of  dry  sand,  by  weight,  exposed 
to  the  air  for  twenty-four  hours  and  then  immersed  in  water  for  six 
days,  must  have  a  tensile  strength  of  not  less  than  180  Ibs.  per  square 
inch. 

(109)  That  cement  mast  be  ground  so  fine  that  90  per  cent  of  it 
will  pass  through  a  sieve  of  10,000  meshes  per  square  inch. 

(110)  That  pats  of  neat  cement  set  in  the  air  and  then  immersed 
in  boiling  water  for  twenty-four  hours  must  show  no  checks  or  cracks. 

(111)  That  cement  must  be  sufficiently  fresh  to  have  lost  no  strength 
from  age,  but  it  must  not  be  so  fresh  as  to  be  "hot"  and  quick-setting. 
Neat  cement  at  temperature  of  70°  F.  must  not  take  an  initial  set  in 
less  than  thirty  minutes,  nor  its  final  set  in  less  than  one  hour. 

(112)  That  the  contractor  must  provide  adequate  storage  and  enough 
cement  ahead  to  enable  seven-day  tests  to  be  made  before  cement  has 
to  be  used. 

(113)  That   the  contractor  must  furnish  every  reasonable  facility 
to  the  inspectors  for  drawing  samples  of  cement,  and  not  less  than  ten 
•days  (holidays  and  Sundays  excluded)  must  elapse  between  time  of 
drawing  the  samples  and  using  the  cement. 

(114)  That  cement  must  at  all  times  be  protected  from  dampness, 
.air-currents,  or  other  source  of  injury. 

(115)  That  the  laboratory  tests  given  above  are  not  final.     Should 
the  engineer  at  any  time  deem  any  lot  of  cement  damaged  or  question- 
.able  in  any  respect,  the  same  shall  be  rejected,  although  it  may  pre- 
viously have  met  other  tests. 

(116)  That  cement  must  be  delivered  on  the  work  in  barrels  of 
375  Ibs.  net  weight,  or  in  sacks  of  94  Ibs.  net  weight. 


SPECIFICATIONS  FOR   PORTLAND  CEMENT.  617 


Engineer  Corps,  U.  S.  Army,  1902. 

(1)  The  cement  shall  ^be  an  American  Portland,  dry  and  free  from 
lumps.     By  a  Portland  cement  is  meant  the  product  obtained  from 
the  heating  or  calcining  up  to  incipient  fusion  of  intimate  mixtures, 
either  natural  or  artificial,  or  argillaceous  with  calcareous  substances, 
the  calcined  product  to  contain  at  least  1.7  times  as  much  of  lime,  by 
weight,  as  of  the  materials  which  give  the  lime  its  hydraulic  proper- 
ties, and  to  be  finely  pulverized  after  said  calcination,  and  thereafter 
additions   or   substitutions   for   the  purpose  only  of  regulating  certain 
properties  of  technical  importance   to  be  allowable   to  not  exceeding 
2  per  cent  of  the  calcined  product. 

(2)  The  cement  shall  be  put  up  in  strong,  sound  barrels  well  lined 
with  paper,  so  as  to  be  reasonably  protected  against  moisture,  or  in 
stout  cloth  or  canvas  sacks.     Eacn  package  shall  be  plainly  labeled 
with  the  name  of  the  brand  and  of  the  manufacturer.     Any  package 
broken  or  containing  damaged   cement  may  be  rejected   or  accepted 
as  a  fractional  package,  at  the  option  of  the  United  States  agent  in 
local  charge. 

(3)  Bidders  will  state  the  brand  of  cement  which  they  propose  to 
furnish.     The  right  is  reserved  to  reject  a  tender  for  any  brand  which 
has  not  established  itself  as  a  high-grade  Portland  cement  and  has  not 
for  three  years  or  more  given  satisfaction  in  use  under  climatic  or  other 
conditions  of  exposure  of  at  least  equal  severity  to  those  of  the  work 
proposed. 

(4)  Tenders  will  be  received  only  from  manufacturers  or  their  author- 
ized agents. 

(The  following  paragraph  will  be  substituted  for  paragraphs  3  and  4 
above  when  cement  is  to  be  furnished  and  placed  by  the  contractor: 

No  cement  will  be  allowed  to  be  used  except  established  brands  of 
high-grade  Portland  cement  which  have  been  made  by  the  same  mill 
and  in  successful  use  under  similar  climatic  conditions  to  those  of  the 
proposed  work  for  at  least  three  years.) 

(5)  The  average  weight  per  barrel  shall  not  be  less  than  375  Ibs.  net. 
Four  sacks  shall  contain  one  barrel  of  cement.     If  the  weight  as  deter- 
mined by  test  weighings  is  found  to  be  below  375  Ibs.  per  barrel,  the 
cement  may  be  rejected,  or,  at  the  option  of  the  engineer  officer  in 
charge,  the  contractor  may  be  required  to  supply,  free  of  cost  to  the 
United   States,  an  additional   amount  of   cement  equal   to   the   short- 
age. 


618  CEMENTS,  LIMES,  AND  PLASTERS. 

(6)  Tests  may  be  made  of  the  fineness,  specific  gravity,  soundness, 
time  of  setting,  and  tensile  strength  of  the  cement. 

(7)  Fineness. — Ninety-two  per  cent  of  the  cement  must  pass  through 
a  sieve   made  of  No.   40  wire,  Stubbs  gauge,  having  10,000  openings 
per  square  inch. 

(8)  Specific  gravity. — The  specific  gravity  of  the  cement,  as  deter- 
mined from  a  sample  which  has  been  carefully  dried,  shall  be  between 
3.10  and  3.25, 

(9)  Soundness. — To  test  the  soundness  of  the*- cement,  at  least  two 
pats  of  neat  cement  mixed  for  five  minutes  with  20  per  cent  of  water 
by  weight  shall  be  made  on  glass,  each  pat  about  3  inches  in  diameter 
and  J  inch  thick  at  the  center,  tapering  thence  to  a  thin  edge.     The 
pats  are  to  be  kept  under  a  wet  cloth  until  finally  set,  when  one  is  to 
be  placed  in  fresh  water  for  twenty-eight  days.     The  second  pat  will 
be  placed  in  water  which  will  be  raised  to  the  boiling-point  for  six  hours, 
then  allowed  to  cool.     Neither  should  show  distortion  or  cracks.     The 
boiling  test  may  or  may  not  reject  at  the  option  of  the  engineer  officer 
in  charge. 

(10)  Time  of  setting. — The  cement  shall  not  acquire  its  initial  set 
in  less  than  forty-five  minutes  and  must  have  acquired  its  final  set  in 
ten  hours. 

(The  following  paragraph  will  be  substituted  for  the  above  in  case 
a  quick-33tting  cement  is  desired: 

The  cement  shall  not  acquire  its  initial  set  in  less  than  twenty  nor 
more  than  thirty  minutes,  and  must  have  acquired  its  final  set  in  not 
less  than  forty-five  minutes  nor  in  more  than  two  and  one-half 
hours.)  #.- 

The  pats  made  to  test  the  soundness  may  be  used  in  determining 
the  time  of  setting.  The  cement  is  considered  to  have  acquired  its- 
initial  set  when  the  pat  will  bear,  without  being  appreciably  indented,, 
a  wire  -fa  inch  in  diameter  loaded  to  weigh  J  Ib.  The  final  set  has  been 
acquired  when  the  pat  will  bear,  without  being  appreciably  indented, 
a  wire  -fa  inch  in  diameter  loaded  to  weigh  1  Ib. 

(11)  Tensile  strength. — Briquettes  made  of  neat  cement,  after  being 
kept  in  air  for  twenty-four  hours  under  a  wet  cloth  and  the  balance 
of  the  time  in  water,  shall  develop  tensile  strength  per  square  inch  as 
follows : 

After  seven  days,  450  Ibs.;    after  twenty-eight  days,  540  Ibs. 
Briquettes  made  of  1  part  cement  and  3  parts  standard  sand,  by 
weight,  shall  develop  tensile  strength  per  square  inch  as  follows: 
After  seven  days,  140  Ibs.;   after  twenty-eight  days,  220  Ibs. 


SPECIFICATIONS  FOR  PORTLAND  CEMENT.  619 

(In  case  quick-setting  cement  is  desired,  the  following  tensile  strength 
shall  be  substituted  for  the  above: 

Neat  briquettes :  After  seven  days,  400  Ibs,;  after  twenty-eight  days, 
480  Ibs. 

Briquettes  of  1  part  cement  to  3  parts  standard  sand:  After  seven 
days,  120  Ibs. ;  after  twenty-eight  days,  180  Ibs.) 

(12)  The  highest  result  from  each  set  of  briquettes  made  at  any 
one  time  is  to  be  considered  the  governing  test.     Any  cement  not  show- 
ing an  increase  of  strength  in  the  twenty-eight-day  tests  over  the  seven- 
day  tests  will  be  rejected. 

(13)  When  making  briquettes  neat  cement  will  be  mixed  with  20 
per  cent  of  water  by  weight,  and  sand  and  cement  with  12J  per  cent 
of  water  by  weight.     After  being  thoroughly  mixed  and  worked  for 
•five  minutes,  the  cement  or  mortar  will  be  placed  in  the  briquette  mold 
in  four  equal  layers,  and  each  layer  rammed  and  compressed  by  thirty 
blows  of  a  soft  brass  or  copper  rammer  three  quarters  of  an  inch  in 
diameter  (or  seven  tenths  of  an  inch  square,  with  rounded  corners), 
weighing  1  Ib.     It  is  to  be  allowed  to  drop  on  the  mixture  from  a  height 
of  about  half  an  inch.     When  the  ramming  has  been  completed,  the 
surplus  cement  shall  be  struck  off  and  the  final  layer  smoothed  with 
a  trowel  held  almost  horizontal  and  drawn  back  with  sufficient  pressure 
to  make  its  edge  follow  the  surface  of  the  mold. 

(14)  The  above  are  to  be  considered   the  minimum  requirements. 
Unless  a  cement  has  been  recently  used  on  work  under  this  office,  bidders 
will  deliver  a  sample  barrel  for  test  before  the  opening  of  bids.     If  this 
sample  shows  higher  tests  than  those  given  above,  the  average  of  tests 
made  on  subsequent  shipments  must  come  up  to  those  found  with  the 
sample. 

(15)  A  cement  may  be  rejected  in  case  it  fails  to  meet  any  of  the 
above  requirements.     An  agent  of  the  contractor  may  be  present  at 
the  making  of  the  tests,  or,  in  case  of  the  failure  of  any  of  them,  they 
may  be  repeated  in  his  presence.     If  the  contractor  so  desires,  the  en- 
gineer officer  in  charge  may,  if  he  deem  it  to  the  interest  of  the  United 
States,  have  any  or  all  of  the  tests  made  or  repeated  at  some  recognized 
standard  testing  laboratory  in  the  manner  herein,  specified.     All  ex- 
penses of  such  tests  to  be  paid  by  the  contractor.     All  such  tests  shall 
be  made  on  samples  furnished  by  the  engineer  officer  from  cement  ac- 
tually delivered  to  him. 


620  CEMENTS,  LIMES,  AND  PLASTERS. 


U.  S.  Reclamation  Service,  1904. 

1.  Definition. — The  cement  shall  be  high-grade   Portland  cement, 
By  the  term  Portland  cement  is  to  be  understood  the  material  obtained 
by  finely  pulverized  clinker  produced  by  burning  to  semi-fusion  an  inti- 
mate mixture  of  finely  ground  calcareous  and  argillaceous  materials. 

2.  Composition. — It  must  be  of  normal  composition,  in  which  the 
proportion  of  the  sum  of  calcium  oxide  and  alkalies  to  the  sum  of  the 
silica,  alumina,  and  ferric  oxide  must  not  be  less  than  1.7  to  1  nor  more 
than  2.2  to  1.     It  shall  not  contain  over  3  per  cent  of  magnesia  nor  2J 
per  cent  of  sulphate  of  lime.     But  in  certain  cases  where  such  amounts 
of  these  substances  are  objectionable  the  engineer  in  charge  may  specify 
lower  percentages.     Its  freedom  from  uncombined  lime  shall  be  deter- 
mined as  in  article  12.     The  question  of  adulteration  may  be  determined 
either  by  chemical  analyses  or  by  inspection  of  the  process  at  the  factory. 

3.  Bids. — Bids  will  be  received  only  from  manufacturers  or  their 
authorized  agents,  and  the  name  of  the  brand  offered  shall  in  all  cases 
be   stated. 

4.  Weight  per  barrel  or  sack. — The  average  weight  per  barrel  shall 
not  be  less  than  375  Ibs.  net.     Four  sacks  shall  contain  1  barrel  of  cement. 
If  the  weight  as  determined  by  test  weighings  is  found   to   be  below 
375  pounds  per  barrel,  the  contractor  may  be  required  to  supply,  free 
of  cost  to  the  United  States,  an  additional  amount  of  cement  equal 
to  the  shortage. 

5.  Barrels ;  damaged  cement. — If  the  cement  is  delivered  in  barrels, 
the  barrels  shall  be  strong  and  lined  with  paper,  and  the  cement  shall 
be  free  from  lumps.     Any  package  that  is  broken  or  that  contains  dam- 
aged cement  may  be  rejected  by  the  United  States  agent  in  local  charge. 

6.  Sampling. — Samples  of  cement  are  to  be  taken  from  the  barrels 
or  sacks  with  a  sampling-tube  in  such  manner  as  to  secure  fair  average 
of  the  packages.     They  are  to  be  taken  from  every  tenth  barrel  or  for- 
tieth sack  and  numbered,  and  the  packages  from  which  they  are  taken 
to  be  sealed  and   corresponding  numbers  attached  for  future  identifi- 
cation.     The   quantities    taken    are   to   be   kept   separate   and   tested 
separately.     Where  the  results  of  tests  indicate  variation  in  the  quality 
of  the  cement,  additional  barrels  or  sacks  will  be  sampled  and  tested. 

7.  Aeration  and  testing. — No  cement  shall  be  shipped  until  at  least 
sixty  days  after  its  manufacture,  except  that  in  case  of  an  emergency, 
and  with  the  approval  of  the  engineer  in  charge,  a  shorter  time  may 
be  allowed,  but  if  the  cement  shows  indications  of  unsoundness,  a  longer 


SPECIFICATIONS  FOR  PORTLAND  CEMENT.  621 

time  may  be  required.  The  contractor  shall  keep  in  storage,  in  sacks 
or  barrels,  such  stocks  of  cement  as  the  engineer  shall  require,  free  of 
expense  to  the  United  States,  for  sampling  and  testing  during  a  period 
of  twenty-eight  days. 

8.  Shipment. — The  engineer  shall  give  notice  in  writing  to  the  con- 
tractor of  the  approximate  requirements  for  cement  shipments  and  of 
dates  for  sampling.     In  all  cases  the  contractor  shall  be  responsible  for 
the  delivery  of  the  cement  in  good  condition  at  the  place  of  consignment. 

9.  Factory  inspection. — The  Government  engineer,  or  his  author- 
ized agent,  shall  at  all   times  have  liberty  to   inspect  the  materials, 
process  of  manufacture,  and  daily  laboratory  records  of   analyses  and 
tests  at  the  cement  works. 

10.  Fineness. — Ninety-five  per  cent  by  weight  must  pass  through 
a  No.  100  sieve  having  10,000  meshes  per  square  inch,  the  wire  to  be 
No.  40  Stubbs  wire  gauge;  and  75  per  cent  by  weight  must  pass  through 
a  No.  200  sieve  having  40,000  meshes  per  square  inch,  the  wire  to  be 
No.  48  Stubbs  wire  gauge. 

11.  Specific  gravity. — The  specific  gravity  of  the  cement  shall  not 
be  less  than  3. 

12.  Soundness. — Pats  are  to  be  made  of  neat  mortar  of  normal 
consistency.     The  pats  are  to  be  molded  on  glass  plates.     They  are  to  be 
circular  in  shape,  3  inches  in  diameter,  J  inch  thick  in  the  center,  arid 
drawn  to  a  thin  edge  at  their  circumference,  and  are  to  be  kept  under 
a  wet  coth,  or  in  a  moist  atmosphere,  until  finally  set.     One  pat  is  to 
be  put  in  water,  the  temperature  of  which  is  to  be  raised  to  the  boiling- 
point  and  kept  at  that  point  for  six  hours.     If  the  pat  softens,  cracks, 
warps,  or  disintegrates,  the  cement  is  unsound. 

13.  Time  of  setting. — The  cement  shall  not  acquire  its  initial  set  in 
less  than  forty-five  minutes,  and  must  acquire  its  final  set  within  twelve 
hours.     The  pats  made  to  test  the  soundness  may  be  used  in  determin- 
ing the  time  of  setting.     The  cement  is  considered  to  have  acquired 
its  initial  set  when  the  pat  will  bear,  without  being  appreciably  indented, 
a  wire  TV  inch  in  diameter  loaded  to  weigh  one  fourth  pound.     The 
final  set  has  been  acquired  when  the  pat  will  bear,  without  being  appre- 
ciably indented,  a  needle  -fa  inch  in  diameter  loaded  to  weigh  one  pourd. 

14.  Making  briquettes. — In  making  briquettes,  neat  cement  mortar 
of  normal   consistency  will   be  used.     The  mortar  will  be  thoroughly 
mixed  with  a  trowel  and  kneaded  into  the  molds  with  the  thumbs,  a 
blunt  stick,  or  a  plunger.     Six  briquettes  will  be  made  from  each  sample. 
In  making  sand  briquettes,  the  proportions  shall  be  one  part  by  weight 
of  cement  to  three  parts  of  standard  crushed  quartz  sand  and  about 


622  CEMENTS,  LIMES,  AND  PLASTERS. 

half  as  much  water  as  is  used  for  neat  briquettes.     Six  briquettes  will 
be  made  from  each  sample. 

15.  Tensile    strength. — The   neat  briquettes  prepared  as  specified 
above  shall  stand  a  minimum  tensile  strain  per  square  inch  as  follows : 

For  one  day  in  air  and  six  days  in  water 450  Ibs. 

For  one  day  in  air  and  twenty-seven  days  in  water. . .   550    " 

'  •  f* 

The  sand-mortar  briquettes,  prepared  as  specified  above,  shall  stand 

a  minimum  tensile  strain  per  square  inch  as  follows : 

After  one  day  in  air  and  six  days  in  water «. 175  Ibs. 

After  one  day  in  air  and  twenty-seven  days  in  water . .   225    ' ' 

16.  Requirements. — The  above  are  to  be  considered  the  minimum 
requirements.     The  neat  tests  are  to  be  considered  of  less  value  than 
those  of  sand  and  cement.     The  twenty-eight-day  tests  must  always 
be  higher  than  the  seven-day  tests.     A  cement  may  be  rejected  which 
fails  to  meet  any  of  the  above  requirements. 


Canadian  Society  of  Civil  Engineers.* 

The  whole  of  the  cement  is  to  be  well-burned  pure  Portland  cement, 
of  the  best  quality,  free  from  free  lime,  slag  dust,  or  other  foreign  mate- 
rial. 

(1)  Fineness. — The  cement  shall  be  ground  so  fine  that  the  residue 
on  a  sieve  of  10,000  meshes  to  the  square  inch  shall  not  exceed  10  per 
cent  of  the  whole  by  weight,  and  the  whole  of  the  cement  shall  pass 
a  sieve  of  2500  meshes  to  the  square  inch. 

(2)  Specific  gravity. — The  specific  gravity  of  the  cement  shall  be 
at  least  3.09,  and  shall    not  exceed    3.25  for  fresh  cement,  .the  term 
" fresh"  being  understood  to  apply  to  such  cements  as  are  not  more 
than  two  months  old. 

(3)  Tests. — The  cement  shall  be  subjected  to  the  following  tests: 
(a)  Blowing  test. — Mortar  pats  of  neat  cement  thoroughly  worked 

shall  be  troweled  upon  carefully  cleaned  5-inch  by  2J-inch  ground- 
glass  plates.  The  pats  shall  be  about  J  inch  thick  in  the  center  and 
worked  off  to  the  sharp  edges  at  the  four  sides.  They  shall  be  covered 
with  a  damp  cloth  and  allowed  to  remain  in  the  air  until  set,  after  which 
they  shall  be  placed  in  vapor  in  a  tank  in  which  the  water  is  heated 
to  a  temperature  of  130°  F.  After  remaining  in  the  vapor  six  hours, 

*  Proposed  Canadian  standard  specifications  for  Portland  cement.  Cement, 
vol.  4,  pp.  98-99.  May,  1903. 


SPECIFICATIONS  FOR  PORTLAND  CEMENT.  623 

including  the  time  of  setting  in  air,  they  shall  be  immersed  in  the  hot 
water  and  allowed  to  remain  there  for  eighteen  hours.  After  removal 
from  the  water  the  samples  shall  not  be  curled  up,  shall  not  have  fine 
hair  cracks,  nor  large  expansion  cracks,  nor  shall  they  be  distorted. 
If  separated  from  the  glass,  the  samples  shall  break  with  a  sharp,  crisp 
ring. 

(b)  Tensile  est  (neat  cement). — Briquettes  made  of  neat  cement 
mixed  with  about  20  per  cent  of  water,  by  weight,  after  remaining 
one  day  in  air,  in  a  moist  atmosphere,  shall  be  immersed  in  water, 
and  shall  be  capable  of  sustaining  a  tensile  stress  of  250  Ibs.  per  square 
inch  after  submersion  for  two  days,  400  Ibs.  per  square  inch  after  sub- 
mersion for  six  days,  500  Ibs.  per  square  inch  after  submersion  for 
twenty-seven  days.  The  tensile  test  shall  be  considered  as  the  aver- 
age of  the  strength  of  five  briquettes,  and  any  cement  showing  a  decrease 
in  tensile  strength  on  or  before  the  twenty-eighth  day  shall  be  rejected. 
(Sand  and  cement.) — The  sand  for  standard  tests  shall  be  clean  quartz, 
crushed  so  that  the  whole  shall  pass  through  a  sieve  of  400  meshes  to 
the  square  inch,  but  shall  be  retained  on  a  sieve  of  900  meshes  per  square 
inch.  The  sand  and  cement  shall  be  thoroughly  mixed  dry,  and  then 
about  10  per  cent  of  their  weight  of  water  shall  be  added,  when  the 
briquettes  are  to  be  formed  in  suitable  molds.  After  remaining  in  a 
damp  chamber  for  twenty-four  hours  the  briquettes  shall  be  immersed 
in  water,  and  briquettes  made  in  the  proportion  of  one  of  cement  to 
three  of  sand,  by  weight,  shall  bear  a  tensile  stress  of  125  Ibs.  per  square 
inch  after  submersion  for  six  days,  and  200  Ibs.  per  square  inch  after 
submersion  for  twenty-eight  days.  Sand  and  cement  briquettes  shall 
not  show  a  decrease  in  tensile  strength  at  the  end  of  twenty-eight  days 
or  subsequently. 

(4)  The  manufacturer  shall,  if  required,  supply  chemical  analyses 
of  the  cement. 

(5)  Packing. — The  cement  shall  be  packed  either  in  stout  air-  and 
water-tight  casks,  carefully  lined  with  strong  brown  paper,  or  in  strong 
air-  and  water-tight  bags. 

(6)  The  manufacturer  shall  give  a  certificate  with  each  shipment 
of  cement,   stating    (1)  the   date   of  manufacture;     (2)  the  tests   and 
analyses  which  have  been  obtained  for  the  cement  in  question  at  the 
manufacturer's  laboratory;    (3)  that  the  cement  does  not  contain  any 
adulteration. 


624  CEMENTS,  LIMES,  AND  PLASTERS. 


Concrete-steel  Engineering  Company.* 

No  cement  will  be  allowed  to  be  used  except  established  brands  of 
high-grade  Portland  cement  which  has  been  in  successful  use  under 
similar  conditions  to  the  work  proposed  for  at  least  three  years,  and 
has  been  seasoned  or  subjected  to  aeration  for  at  least  thirty  days  before 
leaving  the  factory.  All  cement  shall  be  dry  and  free  from  lumps, 
and  immediately  upon  receipt  shall  be  stored  in  a  dry,  well-covered, 
and  ventilated  place  thoroughly  protected  from'-  the  weather.  If 
required  the  contractor  shall  furnish  a  certified  statement  of  the  chem- 
ical composition  of  the  cement  and  of  the  raw  material  from  which  it  is 
manufactured. 

The  fineness  of  the  cement  shall  be  such  that  at  least  90  per  cent 
will  pass  through  a  sieve  of  No.  40  wire,  Stubbs  gauge,  having  10,000 
openings  per  square  inch,  and  at  least  75  per  cent  will  pass  through  a 
sieve  of  No.  45  wire,  Stubbs  gauge,  having  40,000  openings  per  square 
inch. 

Samples  for  testing  may  be  taken  from  every  bag  or  barrel,  but 
usually  for  tests  of  100  barrels  a  sample  will  be  taken  from  every  tenth 
barrel.  The  samples  will  be  mixed  thoroughly  together  while  dry, 
and  the  mixture  be  taken  as  the  sample  for  test. 

Tensile  tests  will  be  made  on  specimens  prepared  and  maintained 
until  tested  at  a  temperature  not  less  than  60°  F.  Each  specimen  will 
have  an  area  of  1  square  inch  at  the  breaking  section  and  after  being 
allowed  to  harden  in  moist  air  for  twenty-four  hours  will  be  immersed 
and  maintained  under  water  until  tested. 

The  sand  used  in  preparing  test  specimens  shall  be  clean,  sharp, 
crushed  quartz  retained  on  a  sieve  of  30  meshes  per  lineal  inch,  and 
passing  through  a  sieve  of  20  meshes  per  lineal  inch.  In  test  speci- 
mens of  one  cement  and  three  sand,  no  more  than  12  per  cent  of  water 
by  weight  shall  be  used.  Specimens  prepared  from  a  mixture  of  one 
part  cement  and  three  parts  sand,  parts  by  weight,  shall  after  seven 
days  develop  a  tensile  strength  of  not  less  than  170  Ibs.  per  square  inch, 
and  not  less  than  240  Ibs.  per  square  inch  after  twenty-eight  days. 
Cement  mixed  neat  from  20  per  cent  to  25  per  cent  of  water  to  form 
a  stiff  paste  shall,  after  30  minutes,  be  appreciably  indented  by  the  end 
of  a  wire  inch  TV  in  diameter  loaded  to  weigh  J  Ib.  Cement  made  into 

*  The  specifications  from  which  this  section  is  taken  were  published  in  Cement, 
vol.  4,  pp.  105-108,  May,  1903.  They  are  for  concrete-steel  structures  on  the 
Melan,  Thacher,  and  Von  Emperger  patents. 


SPECIFICATIONS  FOR  PORTLAND  CEMENT.  625 

thin  pats  on  glass  plates  shall  not  crack,  scale,  or  warp  under  the  fol- 
lowing treatment:  Three  pats  will  be  made  and  allowed  to  harden  in 
moist  air  at  from  60°  to  70°  F. ;  one  of  these  will  be  placed  in  fresh  water 
for  twenty-eight  days,  another  will  be  placed  in  water  which  will  be 
raised  to  the  boiling-point  for  six  hours  and  then  allowed  to  cool,  and 
the  third  is  to  be  kept  in  the  air  of  the  prevailing  outdoor  temperature. 


British   Standard    Specifications.* 

Quality  and  preparation. — (1)  The  cement  is  to  be  prepared  by 
intimately  mixing  together  calcareous  and  argillaceous  materials,  burn- 
ing them  at  a  clinkering  temperature  and  grinding  the  resulting  clinker. 
No  addition  of  any  material  is  to  be  made  after  burning,  except  when 
desired  by  the  manufacturer,  and  if  not  prohibited  in  writing  by  the 
consumer,  in  which  case  calcium  sulphate  or  water  may  be  used.  The 
cement,  if  watered,  shall  contain  not  more  than  2  per  cent  of  water, 
whether  that  water  has  been  added  or  has  been  naturally  absorbed  from- 
the  air.  If  calcium  sulphate  is  used,  not  more  than  2  per  cent  calcu- 
lated as  anhydrous  calcium  sulphate  of  the  weight  of  the  cement  shall 
be  added. 

Sampling  and  preparation  for  testing  and  analysis. — (2)  As  soon 
as  the  cement  has  been  bulked  at  the  maker's  works,  f  or  on  the  works 
in  connection  with  which  the  material  is  to  be  used,  at  the  consumer's 
option,  samples  for  testing  are  to  be  taken  from  each  parcel,  each  sample 
consisting  of  cement  from  at  least  twelve  different  positions  in  the  same 
heap,  so  distributed  as  to  insure,  as  far  as  is  practicable,  a  fair  average 
sample  of  the  whole  parcel,  all  to  be  mixed  together  and  the  sample 
for  testing  to  be  taken  therefrom. 

(3)  Before  gauging  the  tests,  the  sample  so  obtained  is  to  be  spread 
out  for  a  depth  of  3  inches  for  twenty-four  hours,  in  a  temperature  of 
58°  to  64°  F. 

(4)  In  all  cases  where  consignments  are  of  100  tons  and  upwards 
samples  selected  as  above  from  each  consignment,  either  at  the  maker's 
works  or  after  delivery  at  the  works  where  the  cement  is  to  be  used, 
are  to  be  sent  for  expert  testing  and  for   chemical  analysis.     In  no 
case  is  cement  so  tested  and  analyzed  to  be  accepted  or  used  unless 

*  British  standard  specifications  for  Portland  cement.  Engineering  News, 
vol.  53,  pp.  227-228.  March  2,  1905. 

t  Should  the  consumer  desire  to  stipulate  for  any  special  quantity,  the  size  of  the 
heap  should  be  stated. 


626  CEMENTS,  LIMES,  AND  PLASTERS. 

previously  certified  in  writing  by  the  consumer  to  be  of  satisfactory 
quality.  Payment  for  such  tests  and  analyses  to  be  made  by  the  con- 
sumer, the  manufacturer  supplying  the  cement  required  for  the  same 
free  of  charge.  When  consignments  of  less  than  100  tons  have  to  be 
supplied,  the  maker  shall,  if  required,  give  certificates  for  each  delivery, 
to  the  effect  that  such  cement  complies  with  the*  terms  of  this  standard 
specification,  with  regard  to  quality,  tests,  and  chemical  analyses,  no 
payment  being  made  by  the  consumer  for  such  certificate  nor  for  the 
making  of  such  tests  and  analyses. 

(5)  Should  it  be  deemed  more  convenient  by  "the  consumers  that 
the  samples  for  testing  should  be  taken  at  the  makers'  works  before 
delivery,  the  latter  are,  in  that  event,  to  afford  full  facilities  to  the  inspector 
who  may  be  appointed  by  the  consumers  to  sample  the  cement  as  he 
may  desire  at  the  makers'  works,  and  subsequently  to  identify  each 
parcel  as  it  may  be  dispatched,  with  that  sampled  by  him.  No  parcel 
is  to  be  sent  away  unless  a  written  order  has  been  previously  received 
by  the  makers  from  the  said  consumer  to  the  effect  that  the  material 
in  question  has  been  approved. 

Fineness  and  sieves. — (6)  The  cement  shall  be  ground  to  comply 
with  the  following  degrees  of  fineness,  viz.: 

The  residue  on  a  sieve  76X76  =  5776  meshes  per  square  inch  is  not 
to  exceed  5  per  cent. 

The  residue  on  a  sieve  180X180  =  32,400  meshes  per  square  inch    « 
is  not  to  exceed  22J  per  cent. 

The  sieves  are  to  be  prepared  from  standard  wire;  the  size  of  the 
wire  for  the  5776  mesh  is  to  be  .0044  inch  and  for  the  32,400  mesh 
.0018  inch.  The  wire  shall  be  woven  (not  twilled),  the  cloth  being 
carefully  mounted  on  the  frames  without  distortion. 

Specific  gravity. — (7)  The  specific  gravity  of  the  cement  shall  be  not 
less  than  3.15  when  sampled  and  hermetically  sealed  at  the  makers' 
works,  nor  less  than  3.10  if  sampled  after  delivery  to  the  consumer. 

Chemical  composition. — (8)  The  cement  is  to  comply  with  the  follow- 
ing conditions  as  to  its  chemical  composition.  There  shall  be  no  excess 
of  lime,  that  is  to  say,  the  proportion  of  lime  shall  be  not  greater  than 
is  necessary  to  saturate  the  silica  and  alumina  present.  The  percent- 
age of  insoluble  residue  shall  not  exceed  1.5  per  cent;  that  of  mag- 
nesia shall  not  exceed  3  per  cent,  and  that  of  sulphuric  anhydride  shall 
not  exceed  2.5  per  cent. 

Tensile  tests. — (9)  The  quantity  of  water  used  in  gauging  shall  be 
appropriate  to  the  quality  of  the  cement,  and  shall  be  so  proportioned 
that  when  the  cement  is  gauged  it  shall  form  a  smooth,  easily  worked 


SPECIFICATIONS  FOR  PORTLAND  CEMENT.  627 

paste  that  will  leave  the  trowel  cleanly  in  a  compact  mass.  Fresh 
water  is  to  be  used  for  gauging,  the  temperature  thereof,  and  of  the  test- 
room  at  the  time  the  said  operations  are  performed,  being  from  58°  to 
64°  F. 

The  cement  gauged  as  above  is  to  be  filled,  without  mechanical  ram- 
ming, into  molds ;  each  mold  resting  upon  an  iron  plate  until  the  cement 
has  set.  When  the  cement  has  set  sufficiently  to  enable  the  mold  to  be 
removed  without  injury  to  the  briquette,  such  removal  is  to  be  effected. 
The  said  briquettes  shall  be  kept  in  a  damp  atmosphere  and  placed  in 
fresh  water  twenty-four  hours  after  gauging  and  kept  there  until  broken, 
the  water  in  which  the  test  briquettes  are  submerged  being  renewed 
every  seven  days  and  the  temperature  thereof  maintained  between  58° 
and  64°  F. 

Neat  tests. — (10)  Briquettes  of  neat  cement  are  to  be  gauged  for 
breaking  at  seven  and  twenty-eight  days,  respectively,  six  briquettes 
for  each  period.  The  average  tensile  strength  of  the  six  briquettes 
shall  be  taken  as  the  accepted  tensile  strength  for  each  period.  For 
breaking,  the  briquette  is  to  be  held  in  strong  metal  jaws,  the  briquettes 
being  slightly  greased  where  gripped  by  the  jaws.  The  load  must 
then  be  steadily  and  uniformly  applied,  starting  from  zero,  increasing 
at  the  rate  of  100  Ibs.  in  twelve  seconds.  The  briquettes  are  to  bear 
on  the  average  not  less  than  the  following  tensile  stresses  before  breaking: 

7  days  from  gauging 400  Ibs.  per  square  inch  of  section. 

28  days  from  gauging 500  Ibs.  per  square  inch  of  section. 

The  increase  from  seven  to  twenty-eight  days  shall  not  be  less 
than: 

25%  when  the  7-day  test  falls  between  400  to  450  Ibs.  per  square  inch. 

20%  when  the  7-day  test  falls  between  450  to  500  Ibs.  per  square  inch. 

15%  when  the  7-day  test  falls  between  500  to  550  Ibs.  per  square  inch. 

10%  when  the  7-day  test  falls  between  550  Ibs.  per  square  inch  or 
upwards. 

Sand  tests. — (11)  The  cement  shall  also  be  tested  by  means  of 
briquettes  prepared  from  one  part  of  cement  to  three  parts  by  weight 
of  dry  standard  sand,  the  said  briquettes  being  of  the  shape  described 
for  the  neat-cement  tests;  the  mode  of  gauging,  filling  the  molds,  and 
breaking  the  briquettes  is  also  to  be  similar.  The  proportion  of  water 
used  shall  be  such  that  the  mixture  is  thoroughly  wetted,  and  there 
shall  be  no  superfluous  water  when  the  briquettes  are  formed.  The 
cement  and  sand  briquettes  are  to  bear  the  following  tensile  stresses: 

7  days  from  gauging 120  Ibs.  per  square  inch  of  section. 

28  days  from  gauging 225  Ibs.  per  square  inch  of  section. 


628  CEMENTS,  LIMES,  AND  PLASTERS. 

The  increase  from  seven  to  twenty-eight  days  shall  not  be  less  than 
20  per  cent. 

The  standard  sand  referred  to  above  is  to  be  obtained  from  Leighton 
Buzzard.  It  must  be  thoroughly  washed,  dried,  and  pass  through  a 
sieve  of  20X20  meshes  per  square  inch,  and  must  be  retained  on  a  sieve 
of  30X30  meshes  per  square  inch,  tjae  wires  of  the  sieve  being  .0164-inch 
and  .0108-inch  respectively. 

Setting-time. — (12)  There  shall  be  three  distinct  gradations  of  set- 
ting-time, which  shall  be  designated  as  " quick",  "inedium",  and  "slow".* 

Quick. — The  setting-time  shall  not  be  less  than  ten  minutes  or  more 
than  thirty  minutes. 

Medium. — The  setting-time  shall  not  be  less  than  half  an  hour  or 
more  than  two  hours. 

Slow. — The  setting-time  shall  not  be  less  than  two  hours  or  more 
than  five  hours.* 

The  temperature  of  the  air  in  the  test-room  at  the  time  of  gauging 
and  of  the  water  used  is  to  be  between  58°  and  64°  F. 

The  cement  shall  be  considered  as  "set"  when  a  needle  having  a 
flat  end  -f$  inch  square,  weighing  in  all  2i  Ibs.,  fails  to  make  an  im- 
pression when  its  point  is  applied  gently  to  the  surface. 

Soundness. — (13)  The  cement  shall  be  tested  by  the  Le  Chatelier 
method;  and  is  in  no  case  to  show  a  greater  expansion  than  12  milli- 
meters after  twenty-four  hours'  aeration  and  6  millimeters  after  7  days' 
aeration. 

Note. — The  apparatus  for  conducting  the  Le  Chatelier  test  consists 
of  a  small  split  cylinder  of  spring  brass  or  other  suitable  metal  of  0.5 
millimeter  (.0197  in.)  in  thickness,  30  millimeters  (1.1875  inches)  inter- 
nal diameter,  and  30  millimeters  high,  forming  the  mold,  to  which  on 
either  side  of  the  split  are  attached  two  indicators  165  millimeters  (6.5 
inches)  long  frorn  the  center  of  the  cylinder,  with  pointed  ends. 

In  conducting  the  test  the  mold  is  to  be  placed  upon  a  small  piece 
of  glass  and  filled  with  cement  gauged  in  the  usual  way,  care  being  taken 
to  keep  the  edges  of  the  molds  gently  together  while  this  operation  is 
being  performed.  The  mold  is  then  covered  with  another  glass  plate, 
a  small  weight  is  placed  on  this,  and  the  mold  is  immediately  placed 
in  water  at  58°  to  64°  F.  and  left  there  for  twenty-four  hours. 

The  distance  separating  the  indicator  points  is  then  measured  and 
the  mold  placed  in  cold  water,  which  is  brought  to  the  boiling-point  in 

*  When  a  specially  slow-setting  cement  is  required  the  minimum  time  of 
setting  shall  be  specified. 


SPECIFICATIONS  FOR  .PORTLAND   CEMENT.  629 

15  to  30  minutes  and  kept  boiling  for  six  hours.  After  cooling,  the 
distance  between  the  points  is  again  measured;  the  difference  between 
the  two  measurements  represents  the  expansion  of  the  cement,  which 
must  not  exceed  the  limits  laid  down  in  this  specification. 

(14)  The  tests  and  analyses  hereinbefore  referred  to  shall  in  no  case 
relate  to  a  larger  quantity  of  cement  than  250  tons  sampled  at  one  time. 

Acceptance. — (15)  No  cement  is  to  be  approved  or  accepted  unless 
it  fully  complies  with  the  foregoing  conditions. 


American  Society  for  Testing  Materials,  1904. 

GENERAL   OBSERVATIONS. 

1.  These  remarks  have  been  prepared  with  a  view  of  pointing  out 
the  pertinent  features  of  the  various  requirements  and  the  precautions 
to  be  observed  in  the  interpretation  of  the  results  of  the  tests. 

2.  The  committee  would  suggest  that  the  acceptance  or  rejection 
under  these  specifications  be  based  on  tests  made  by  an  experienced 
person  having  the  proper  means  for  making  the  tests. 

3.  Specific  gravity. — Specific  gravity  is  useful  in  detecting  adultera- 
tion or  uriderburning.     The  result  of  tests  of  specific  gravity  are  not 
necessarily  conclusive  as  an  indication  of  the  quality  of  the  cement,  but 
when  in  combination  with  the  results  of  other  tests  may  afferd  valuable 
indications. 

4.  Fineness. — The  sieves  should  be  kept  thoroughly  dry. 

5.  Time   of  setting. — Great   care  should  be  exercised  to  maintain 
the   test  pieces   under  as   uniform   conditions   as   possible.     A  sudden 
change  or  wide  range  of  temperature  in  the  room  in  which  the  tests  are 
made,  a  very  dry  or  humid  atmosphere,  and  other  irregularities  vitally 
affect  the  rate  of  setting. 

6.  Tensile  strength. — Each   consumer   must   fix   the   minimum   re- 
quirements for  tensile  strength  to  suit  his  own  conditions.     They  shall, 
however,  be  within  the  limits  stated. 

7.  Constancy  of  volume. — The  tests  for  constancy  of  volume  are 
divided  into  two  classes,  the  first  normal,  the  second  accelerated.     The 
latter  should  be  regarded  as  a  precautionary  test  only,  and  not  infallible. 
So  many  conditions  enter  into  the  making  and  interpreting  of  it  that 
it  should  be  used  with  extreme  care. 

8.  In  making  the  pats  the  greatest  care  should  be  exercised  to  avoid 
initial  strains  due  to  molding  or  to  too  rapid  drying  out  during  the  first 
twenty-four   hours.     The   pats   should  be   preserved   under   the   most 


630  CEMENTS,  LIMES,  AND  PLASTERS. 

uniform  conditions  possible,  and  rapid  changes  of  temperature  should 
be  avoided. 

9.  The  failure  to  meet  the  requirements  of  the  accelerated  tests 
need  not  be  sufficient  cause  for  rejection.  The  cement  may,  however, 
be  held  for  twenty-eight  days  and  a  retest  made  at  the  end  of  that  period. 
Failure  to  meet  the  requirements  #t  this  time  should  be  considered 
sufficient  cause  for  rejection,  although  in  the  present  state  of  our  knowl- 
edge it  cannot  be  said  that  such  failure  necessarily  indicates  unsound- 
ness,  nor  can  the  cement  be  considered  entirely  satisfactory  simply 
because  it  passes  the  tests. 

STANDARD    SPECIFICATIONS    FOR    CEMENT. 

1.  General  conditions. — All  cement  shall  be  inspected. 

2.  Cement  may  be  inspected  either  at  the  place  of  manufacture 
or   on   the   work. 

3.  In  order  to  allow  ample  time  for  inspecting  and  testing,  the  cement 
should  be  stored  in  a  suitable  weather-tight  building  having  the  floor 
properly  blocked  or  raised  from  the  ground. 

4.  The  cement  shall  be  stored  in  such  a  manner  as  to  permit  easy 
access  for  proper  inspection  and  identification  of  each  shipment. 

5.  Every  facility  shall  be  provided  by  the  contractor  and  a  period 
of  at  least  twelve  days  allowed  for  the  inspection  and  necessary  tests. 

6.  Cement  shall  be  delivered  in  suitable  packages  with  the  brand 
and  name  of  manufacturer*  plainly  marked  thereon. 

7.  A  bag  of  cement  shall  contain  94  Ibs.  of  cement  net.     Each  barrel 
of  Portland  cement  shall  contain  4  bags,  and  each  barrel  of  natural 
cement  shall  contain  3  bags,  of  the  above  net  weight. 

8.  Cement  failing  to  meet  the  seven-day  requirements  may  be  held 
awaiting  the  results  of  the  twenty-eight-day  tests  before  rejection. 

9.  All  tests  shall  be  made  in  accordance  with  the  methods  proposed 
by  the  Committee  on  Uniform  Tests  of  Cement  of  the  American  Society 
of  Civil  Engineers,  presented  to  the  society  Jan.  21,  1903,  and  amended 
Jan.  20,  1904,  with  all  subsequent  amendments  thereto. 

10.  The  acceptance  or  rejection  shall  be  based  on  the  following 
requirements : 

» 

PORTLAND    CEMENT. 

18.  Definition. — This  term  is  applied  to  the  finely  pulverized  product 
resulting  from  the  calcination  to  incipient  fusion  of  an  intimate  mixture 
of  properly  proportioned  argillaceous  and  calcareous  materials,  and  to 


SPECIFICATIONS  FOR  PORTLAND   CEMENT.  631 

which  no  addition  greater  than  3  per  cent  has  been  made  subsequent 
to  calcination. 

19.  Specific  gravity. — The  specific  gravity  of  the  cement,  thoroughly 
dried  at  100°  C.,  shall  be  not  less  than  3.10. 

20.  Fineness. — It  shall  leave  by  weight  a  residue  of  not  more  than 
8  per  cent  on  the  No.  100,  and  not  more  than  25  per  cent  on  the  No. 
200-sieve. 

21.  Time  of  setting. — It  shall  develop  initial  set  in  not  less  than 
thirty  minutes,  but  must  develop  hard  set  in  not  less  than  one  hour, 
nor  more  than  ten  hours. 

22.  Tensile  strength. — The  minimum  requirements  for  tensile  strength 
for  briquettes  one  inch  square  in  section  shall  be  within  the  following 
limits,  and  shall  show  no  retrogression  hi  strength  within  the  periods 
specified : 

NEAT  CEMENT. 
Age.  Strength. 

24  hours  in  moist  air 150 — 200  Ibs. 

7  days  (1  day  in  air,  6  days  in  water) 450 — 550  ' ' 

28  days  (1  day  in  air,  27  days  in  water) 550 — 650  " 

One  Part  Cement,  Three  Parts  Sand: 

7  days  (1  day  in  moist  air,    6  days  in  water) 150 — 200   u 

28  days  (1  day  in  moist  air,  27  days  in  water) 200 — 300  ' ' 

23.  Constancy  of  volume. — Pats  of  neat  cement  about  three  inches 
in  diameter,  one  half  inch  thick  at  the  center,  and  tapering  to  a  thin 
edge,  shall  be  kept  in  moist  air  for  a  period  of  twenty-four  hours. 

(a)  A  pat  is  then  kept  in  air  at  normal  temperature  and  observed 
at  intervals  for  at  least  28  days. 

(6)  Another  pat  is  kept  in  water  maintained  as  near  70°  F.  as  prac- 
ticable, and  observed  at  intervals  for  at  least  28  days. 

(c)  A  third  pat  is  exposed  in  any  convenient  way  in  an  atmosphere 
of  steam,  above  boiling  water,  in  a  loosely  closed  vessel  for  five  hours. 

24.  These  pats,  to  satisfactorily  pass  the  requirements,  shall  remain 
firm  and  hard  and  show  no  signs  of  distortion,  checking,  cracking  or 
disintegration. 

25.  Sulphuric  acid  and  magnesia. — The  cement  shall  not  contain 
more  than  1.75  per  cent  of  anhydrous  sulphuric  acid  (SOs),  nor  more 
than  4  p'er  cent  of  magnesia  (MgO). 


PART  VIL     PUZ20LAN   CEMENTS. 


CHAPTER  XLI. 
PUZZOLANIC  MATERIALS  IN  GENERAL. 

PUZZOLANIC  materials  include  all  those  natural  or  artificial  materials 
which  are  capable  of  forming  hydraulic  cements  on  being  simply  mixed 
with  lime,  without  the  use  of  heat.  Many  materials  possess  this  property, 
but  relatively  few  have  ever  attained  to  sufficient  commercial  impor- 
tance to  be  discussed  here.  In  composition  the  puzzolanic  materials 
are  largely  made  up  of  silica  and  alumina,  usually  with  more  or  less 
iron  oxide;  some,  as  the  slags  used  in  cement-manufacture,  carry  also 
notable  percentages  of  lime.  As  might  be  inferred  from  this  compo- 
sition, most  of  the  puzzolanic  materials  possess  hydraulicity  to  a  greater 
or  less  degree  of  themselves,  but  the  addition  of  lime  usually  greatly 
increases  their  hydraulic  power. 

The  term  puzzolan,  here  adopted  for  this  group  of  cementing  mate- 
rials, is  a  corruption  of  the  adjective  form  of  the  name  pozzuolana. 
It  has  no  particular  etymological  excuse  for  existence,  but  will  be 
accepted  in  this  volume  for  the  sake  of  uniformity,  as  it  seems  to  have 
been  adopted  by  various  authorities  in  the  United  States. 

Natural  Puzzolanic  Materials. 

Natural  puzzolanic  materials  are  quite  widely  distributed,  though 
they  have  never  attained  much  commercial  importance,  save  in  Europe. 
As  regards  their  origin,  they  are  of  two  classes:  In  the  first  class  may 
be  included  all  those  which  are  the  direct  products  of  volcanic  action, 
the  material  being  a  fine  volcanic  ash  or  dust  deposited  either  on  the 
slopes  of  the  volcano  or  carried  by  the  wind  to  lakes  or  streams  in 
which  the  ash  is  deposited.  This  group  includes  the  more  active  puzzo- 
lanic materials,  its  chief  representatives  being  pozzuolana  proper,  san- 

632 


PUZZOLANIC  MATERIALS  IN  GENERAL. 


633 


torin,  tosca,  tetin  and  trass.  It  may  be  noted  that  in  origin  materials 
of  this  class  resemble  closely  the  granulated  slags  used  in  slag-cement 
manufacture  both  volcanic  ashes  and  granulated  slags  being  due  to 
the  processes  of  (1)  fusion  of  a  silico-aluminous  material,  and  (2)  rapid 
cooling  of  the  resulting  product  by  ejection  into  air  or  immersion  in 
water.  The  second  class  includes  a  number  of  less  important  (because 
less  active)  hydraulic  materials,  such  as  arenes,  psammites,  etc.,  which 
are  materials  resulting  from  the  decay  of  certain  igneous  rocks. 

The  principal  natural  puzzolanic  materials  will  be  discussed  sepa- 
rately, in  the  following  order:  Pozzuolana  (tosca,  tetin),  trass,  san- 
torin,  arenes. 

Pozzuolana. — Pozzuolana  derives  its  name  from  the  little  town  of 
Pozzuoli,  located  a  few  miles  west  of  Naples,  at  which  point  the  material 
was  first  obtained  'by  the  Greek  colonists,  and  at  a  later  date  by  the 
Romans.  The  material  has  also  been  exploited  at  other  points  near 
Rome  and  Naples. 

TABLE  234. 
ANALYSES  OF  POZZUOLANA  FROM  ITALY. 


Si02 

A1203 

FegOa 

CaO 

MgO     * 

K20 

Na2O 

H20 

1 

58.58 

"~22T74 

4.06 

1.37 

2 

52.66 

14.33 

10.33 

7.66 

3.86 

4.13 

7.03 

3 

44.5 

15.0 

12.0 

8.8 

4.7 

1.4 

4.0 

9.2 

4 

63.18 

19.8 

5.68 

0.35 

5 

60.91 

21.28 

4.76 

1.90 

0.00 

4.37 

6.23 

6 

44.0 

10.5 

29.5 

10.0 

tr. 

1.00 

2.5 

7 

44.5 

15.75 

16.3 

8.96 

tr. 

11.0 

3.5 

8 

46.0 

16.5 

15.5 

10.0 

3.0 

4.0 

5.0 

9 

44.5 

15.5 

12.5 

9.5 

4.4 

10.27 

3.33 

10 

39.0 

14.0 

13.0 

18.0 

3.0 

11.0 

11 

56.31 

15.23 

7.11 

i.74 

1.36 

6.54 

2.84 

6.12 

1.  Pozzuolana,  Rome.     Stanger  and  Blount,  Mineral  Industry,  vol.  5,  p.  71. 


St.  Paul's  Caves.     Thoyn,  Diet.  App.  Chem.,  3d  ed.,  vol.  1,  p.  475. 
Civita  Vecchia.     Berther,  Anal.  Gillmon,  Limes,  Cements,  and  Mortars,  p. 
Naples.     Stanger  and  Blount,  Mineral  Industry,  vol.  5,  p.  71. 

.     Stengel,  Anal.  Zervas,  School  of  Mines  Quart,  vol.  18,  p.  230. 

Vesuvius.     Brown.         Thorpe,  Diet.  App.  Chem.,  3ded.,  vol.  1,  p.  475. 

"  "       3ded.,  vol.  1,  p.  475. 

Dark  gray.  3d  ed.,  vol.  1,  p.  475. 

Light  gray.  "       3d  ed.,  vol.  1,  p.  475. 


10.  Lava,  Vesuvius,  1868.     Thorpe,  Diet.  App.  Chem.,  3d  ed.,  vol.   1,  p.  475. 

11.  Tuff,  Monte  Nuova.     Merrill,  Rocks,  Rock  Weathering  and  Soils,  p.   141. 


Most  of  the  Italian  pozzuolana  is  obtained  from  small  open  cuts, 
or  pits,  though  some  of  these  workings  are  now  of  great  depth.  Those 
of  Trent aremi,  for  example,  are  about  600  feet  deep.  The  various 


634 


CEMENTS,  LIMES,  AND   PLASTERS. 


deposits  differ  greatly  in  the  quality  of  the  materials  obtained  from 
them.  Care  should  therefore  be  exercised  in  selecting  a  spot  for  exploita- 
tion, and  sorting  of  the  material  dug  would  be  advisable  in  order  to 
keep  the  product  of  uniformly  high  grade.  After  extraction  the  ma- 
terial is  screened  and  ground.  In  addition  it  is  occasionally  slightly 
roasted,  which  process  increases  its  ^hydraulic  properties.  Carelessness, 
both  in  the  mining  and  in  the  later  preparation  of  the  pozzuolana, 
has  brought  the  Italian  article  somewhat  into  disrepute  among  Euro- 
pean engineers.  In  consequence  it  is  losing  ground  with  respect  both 
to  pozzuolana  from  the  Azores  and  to  trass  from  Rhenish  Prussia. 

Pozzuolana  is  also  obtained  at  a  number  of  localities  in  southeastern 
France.  These  localities  occur  mostly  in  three  areas :  (1)  in  the  Auvergne 
Mountains,  lying  in  the  Departments  of  Puy  de  Dome  and  Cantal; 
(2)  in  the  Mountains  du  Vivarais,  between  Haute  Loire  and  Ardeche; 
and  (3)  in  the  Department  of  PHerault,  near  the  Gulf  of  Lyons. 

TABLE  235. 
ANALYSES  OF  POZZUOLANA  FROM  FRANCE. 


1. 

2. 

3. 

4. 

5. 

6. 

7. 

Silica  (SiO2)  
Alumina  (A12O3)  

47  ..9 

47.1 

46.05 
17  0 

48.0 

35.09 
17  65 

30.73 
11  63 

38.50 
18  35 

Iron  oxide  (Fe2O3)  .... 
Lime  (CaO) 

J34.2 
8  2 

39.0  | 
7  0 

20.55 
8  55 

K4{ 

8  10 

16.82 
4  26- 

24.92 
3  73 

14.90 
8  70 

Magnesia  (MgO)  
Alkalies  (K2O,Na2O)  .  . 
Water  (H2O)  

3.9 
2.6 
3  2 

tr. 
4.7 
2  2 

tr. 
6.35 
1  6 

tr. 
4.8 
2  4 

3.17 
n.  d. 
19  06 

2.49 
n.  d. 
19  02 

tr. 
7.30 
7.75 

1.  Auvergne  Mountains,  black.  Thorpe,  Diet.  App.  Chem.,  vol.  1,  p.  475. 

2.  "  reddish-brown.      " 

3.  "  "  brick-red. 

4.  Gravenydre. 

5.  Vivarais  Mountains,  gray.    Vicat,  analyst. 

6.  brown. 

7.  Department  of  1'Herault,  brown.     Vicat,  analyst. 

Pozzuolana  has  been  shipped  from  San  Miguel  and  Terceira  in  the 
Azores,  to  Portugal  for  over  a  hundred  years,  and  has  been  used  with 
very  satisfactory  results  in  many  important  buildings,  harbor  works,  etc. 
The  Azores  pozzuolana  varies  in  color  from  yellowish  to  brownish,  and 
sometimes  to  grayish.  It  is  frequently  so  fine-grained  as  not  to  require 
screening  or  grinding  before  use.  A  reddish  colored  v.ariety  from  the 
same  islands  is  termed  tetin. 

A  similar  ash,  locally  called  "tosca",  is  obtained  from  Teneriffe, 
one  of  the  Canary  Islands,  and  shipped  to  Spain  for  use  as  a  cementing 
material. 


PUZZOLANIC  MATERIALS  IN  GENERAL. 

TABLE  236. 
ANALYSES  OP  POZZUOLANA  FROM  THE  AZORES  ISLANDS. 


635 


1. 

2. 

3. 

Silica  (SiO2)  

60  90 

54  70 

57  73 

11.14 

20  50 

13  81 

Iron  oxide  (Fe2O3)  

12  78 

6  30 

12  02 

Lime  (CaO)  

2  57 

2  20 

3  74 

Magnesia  (MgO)  

1  45 

1  70 

1  73 

Potash  (K2O)  

2  64 

3  21 

Soda  (Na2O) 

2  74 

>    2.20< 

2  76 

Water  (HrO) 

5  78 

12  40 

4  66 

1.  From  St.  Miguel.— tetin.  Zervas,     analyst.    School  of  Mines  Quarterly,  vol.  18,  p.  230. 

2.  — pozzuolana.    Chateau, 

3.  "     Terceira.  Zervas, 

Volcanic  materials  of  a  type  somewhat  different  from  normal  pozzuo- 
lana occur  on  Tile  Bourbon,  a  French  island  lying  about  400  miles  east 
of  Madagascar. 

ANALYSIS  OP  VOLCANIC  ASH,  ILE  BOURBON. 

Silica  (SiO2) 25.67 

Alumina  (A12O3) 16.33 

Iron  oxide  (Fe2O3) 40.00 

Magnesia  (MgO) tr. 

Water  (H2O) 17.00 


Trass.  —  Trass  is  a  pale  yellowish  to  grayish  rock,  rough  to  the  feel, 
composed  of  an  earthy  or  compact  pumiceous  dust  mixed  with  fragments 
of  pumice,  trachyte,  carbonized  wood,  etc.  It  is,  so  far  as  origin  is 
concerned,  an  ancient  volcanic  mud.  Trass  occurs  along  the  Rhine, 
in  Rhenish  Prussia,  from  Koln  on  the  north  to  Coblenz  on  the  south. 
The  towns  of  Brohl,  Kruft,  Plaidt,  and  Andernach,  all  located  north- 
west of  Coblenz  and  within  fifteen  miles  of  that  city,  are  prominent 
points  in  connection  with  the  trass  industry.  A  series  of  analyses  of 
trass  and  related  products  is  given  in  Table  237. 

Santorin.  —  The  island  of  Santorin,  or  Thera,  is  one  of  the  most 
southeasterly  of  the  islets  of  the  Grecian  Archipelago,  lying  in  the 
Cyclades  group.  An  ash  called  in  commerce  "santorin  ",  derived  from 


the  volcano  of  the  same 
as  a  cementing  material. 


name,  is  quite  extensively  shipped  for  use 


636  CEMENTS,  LIMES,  AND  PLASTERS. 

TABLE  237. 
ANALYSES  OP  TRASS  AND  RELATED  MATERIALS  FROM  GERMANY. 


SiO2 

A1203 

Fe203 

CaO 

MgO 

K20 

Na2O 

H2O 

1 

46.25 

20.71 

5.48 

2.15 

1.00 

6. 

30~~ 

9.25 

2 

46.6 

20.6 

12.0 

3.0* 

5.0 

12.8 

3 

48.  S4 

18.95 

12.34 

5.41 

'2i42 

0.37 

3.56 

11.94 

4 

53.07 

18.28 

3.43 

1.24 

1.31 

4.17 

3.73 

12.78 

5 

53.58 

19.11 

9.24 

3.21 

0.30 

4.84 

1.87 

7.50 

6 

54.0 

16.5 

6.1 

4.0 

0.7 

JO.O 

7.0 

7 

55.28 

17.34 

3.90 

3.17 

0.87 

4.70 

3.80 

10.63 

8 

57.0 

16.0 

5.0 

2.6 

1.0 

7.0 

1.0 

9.6 

9 

57.5 

10.1 

3.9 

7.7 

1.1 

6.4 

12.6 

10 

58.32 

20.88 

4.15 

2.19 

1.10 

3.91 

4.11 

5.87 

11 

61.10 

12.70 

10.20 

8.10 

1.90 

2.10 

2.10 

1.40 

12 

59.40 

22.70 

2.50 

3.10 

0.80 

3.50 

2.80 

4.80 

13 

60.49 

19.95 

9.37 

3.12 

1.43 

3.40 

1.33 

14 

62.83 

21.55 

4.11 

0.72 

0.42 

3.35 

3.02 

4.19 

15 

66.39 

17.74 

4.97 

0.53 

0.47 

3.05 

1.94 

4.89 

16 

67.60 

11.30 

5.20 

8.20 

2.80 

0.60 

0.50 

3.10 

1.  Trass.   Rhenish.     Thorpe,  Diet.  App.  Chem.,  3d  ed.,  vol.  1,  p.  475. 

2.  Dutch.     Thorpe,  p.  475. 

3.  Andernach.     Thorpe,  p.  475. 

4.  Plaidt.     von  Decken,  Anal.  Zirkel,  Lehrbuch  der  Petrographie,  1894,  vol.  3,  p.  678* 

5.  Zervas,  Anal.  Zervas,  School  of  Mines  Quart.,  vol.  18,  p.  230. 

6.  Andernach.     Chatoney  and  Rivol,  Anal.  Zirkel,  p.  678. 

7.  Kruft.     Mengerschausen,  Anal.  Zervas,  p.  320. 

8.  Brohl.     Berthier,   Anal.    Gillmore,   Limes,   Cements,  and  Mortars,  p.    125. 

9.  Andernach.     Chatoney  and  Rivol,  Anal.  Zirkel,  p.  678. 

10.  Brohl.     Bruhus,  Anal.  Zirkel,  p.  678. 

11.  "          Kyll,  Anal.  Zervas,  p.  320. 

12.  Trachyte  tuff.     Siebengebirge,  Kyll,  Anal.  Zervas,  p.  320. 

13.  "  "        Laacher  See.     Merrill,  Rocks,  Rock  Weathering  and  Soils,  p.  141. 

14.  "  "        Siebengebirge.     Bischof,  Anal.  Zirkel,  p.  675. 

15.  "  "                                        von  der  Marck,  Anal.  Zirkel,  p.  675. 

16.  Leucite  tuff.     Weibern.     Kyll,  Anal.  Zervas,  p.  320. 


TABLE  238. 
ANALYSES  OF  SANTORIN  ASH,  FROM  SANTORIN. 


l. 

2. 

3. 

4. 

Silica  (SiO2)                     .    . 

72  84 

71.44 

63.07 

66  37 

Alumina  (AlgO^       

12  26 

9.87 

15.67 

13  72 

Iron  oxide  (Fe2O3)    

4.35 

3.84 

8.73 

4.31 

Lime  (CaO)         

2.55 

2.64 

3.83 

2.98 

1.58 

1.84 

1.93 

1.29 

Potash  (K2CN 

1  28 

1  86 

1  87 

2  83 

Soda  (Na«O) 

2  65 

3  74 

3  86 

4  22 

Water  (H2O)       

2  25 

4  61 

1.14 

4  06 

1.  Pumiceous  portion.     Feichtinger,  analyst.     Thorpe,  Diet.  App.  Chem.,  vol.  1,  p.  476. 

2.  Fine  ash. 

3.  Obsidian  particles. 

4.  Average  sample.  "  "  School  of  Mines  Quarterly,  vol.  18,  p.  230. 


PUZZOLANIC  MATERIALS  IN   GENERAL. 


637 


Arenes,  etc. — The  materials  called  "arenes"  by  early  French  writers 
on  cement  technology  are  sands  and  residual  material  derived  from 
the  decay  of  various  igneous  rocks,  and  particularly  from  the  decay  of 
the  more  basic  rocks,  such  as  trap,  basalt,  etc.  Such  materials  will 
naturally  vary  greatly  in  composition  and  properties,  but  all  of  them 
agree  in  possessing  feeble  hydraulicity.  -  For  present-day  commercial 
purposes  they  are  practically  worthless. 

TABLE  239. 
ANALYSES  OF  ARENES,  FRANCE. 


1. 

2. 

3. 

4. 

5. 

Silica  (SiO2)     

38.54 

60  33 

42  10 

38.50 

60  30 

Alumina  (AlgO^   

20.00 

21  43 

23  .  65 

29.40 

23.70 

Iron  oxide  (Fe2O3)  

12.00 

8  57 

22.47 

18.10 

10.30 

Lime  (CaO) 

8  OO1 

1     „   ...  ( 

tr 

2  00 

tr 

Magnesia  (MgO) 

n   d 

\    6  .  69  < 

2  50 

Alkalies  (K2O  Na2O) 

n   d 

n   d 

1  28 

1  50 

3  20 

i  Lime  carbonate  (CaCO3). 

1.  Saint  Astier,  Department  Dordogne.    Vicat,  analyst. 

2.  Brest.      Vicat,  analyst. 

3.  Saint  Servan.     Vicat,  analyst. 
4. 

5.  Chateaulin. 

As  might  be  inferred  from  the  examples  given,  natural  materials: 
showing  slightly  hydraulic  properties  are  not  cf  rare  occurrence.  With 
the  exception  of  trass,  santorin  and  pozzuolana  proper,  these  materials 
are  rarely  sufficiently  hydraulic  to  be  of  service  as  bases  for  puzzo- 
lan  cements  or  mortars.  The  feebly  hydraulic  materials  have,  how- 
ever, a  practical  value  which  may  be  noted  briefly  here.  It  is — that, 
owing  to  the  fact  that  they  are  hydraulic,  they  can  be  profitably  sub- 
stituted in  places  where  they  occur  for  common  sand  in  mortar. 

Chelius  has  tested  *  the  fine  material  remaining  after  the  crushing 
of  basalt  in  an  ordinary  stone-crusher.  This  fine  material  (dust  and 
screenings)  gave  the  following  results  as  compared  with  normal  sand; 

TABLE  240. 
STRENGTH  OF  BASALTIC  DUST. 


Tension. 

Compression. 

28  Days. 

90  Days. 

1  Year. 

28  Days. 

90  Days. 

1  Year. 

35.8 

67.8 

Cement  and  normal  sand  
Cement  and  basalt  fines  
Lime  and  normal  sand  

6^3 

7.7 

20.9 
43.6 

237.7 
320.8 

8.5 
11.1 

14.2 
44.9 

Lime  and  basalt  fines  

*  Journ.  Soc.  Chem.  Ind.,  vol.  19,  p.  826. 


838 


CEMENTS,  LIMES,  AND  PLASTERS. 


Part  of  the  superiority,  as  shown  by  these  tests,  of  the  basalt  dust 
to  normal  sand  is  probably  due  to  purely  physical  causes.  In  part, 
however,  it  is  probably  due  to  the  fact  that  the  finely  crushed  basalt 
acted  as  a  puzzolanic  material. 

Range  and  average  composition  of  natural  puzzolanic  materials. — 
From  the  separate  tables  of  analyses  given  in  preceding  paragraphs 
the  following  table  of  average  analyses  have  been  prepared: 

TABLE  «241. 
AVERAGE  ANALYSES  OF  NATURAL  PUZZOLANIC  MATERIALS. 


Pozzuo- 
lana, 
Italy. 

Pozzuo- 
lana, 
France. 

Pozzuo- 
lana, 
Azores. 

Trass, 
Ger- 
many. 

San- 
torin. 

Average 
Natural 
Puzzo- 
lanic 
Material. 

9 

7 

3 

11 

1 

31 

Silica  (SiO2)  

50  98 

41.91 

57.78 

53.78 

66.37 

51.08 

Alumina  (A12O3)           .    . 

15  55 

16  16 

15  15 

17  38 

13  72 

16  30 

Iron  oxide  (Fe2O3)   

14  41 

19  30 

10  37 

6  89 

4  31 

11  13 

Lime  (CaO)       

7  39 

6  93 

2  84 

3  89 

2  98 

5  46 

Magnesia  (MgO)     

1  96 

1  37 

1  63 

1  17 

1  29 

1  50 

Alkalies  (K2O,Na,O)    

6  63 

5  15 

4  52 

6  82 

7  05 

6  21 

Water  (H2O)  

5  09 

7  89 

7  61 

9  22 

4  06 

7  64 

Puzzolanic  materials  in  the  United  States. — Volcanic  ash  and  other 
materials  which  may  be  expected  to  show  puzzolanic  action  occur  ex- 
tensively in  the  western  United  States,  but  few  tests  appear  to  have 
been  made  of  their  hydraulic  properties. 

Mr.  J.  S.  Diller,  in  a  recent  description*  of  the  mineral  resources 
of  the  Redding  district  of  California,  has  noted  that  a  "tuff,  bordering 
the  northern  end  of  the  Sacramento  Valley,  is  very  like  the  trass  of  the 
Rhine  Valley.  This  is  especially  true  of  that  on  Stillwater,  near  the 
Copper  City  road,  or  east  of  Millville,  and  at  a  number  of  points  on  the 
western  side  of  the  Sacramento  Valley.  The  limestone  and  the  tuff 
are  at  several  places  within  a  few  miles  of  each  other,  and  there  is  reason 
to  believe  that  a  good  quantity  of  hydraulic  cement  may  be  made  from 
them  within  convenient  reach  of  the  railroad.  This  matter  is  of  impor- 
tance in  the  construction  of  large  dams  for  irrigation  or  water-power 
in  the  Redding  region.  Similar  volcanic  products  occur  in  Arizona, 
and  have  been  used  locally  as  puzzolanic  materials. 


*  Bulletin  225,  U.  S.  Geological  Survey,  p.  177,  1904. 


PUZZOLAXIC  MATERIALS  IN  GENERAL. 


639 


Artificial  Puzzolanic  Materials. 

Blast-furnace  slag  is  by  far  the  most  prominent  of  the  artificial  poz- 
zuolanic  materials.  Other  artificial  materials  have,  however,  been  used 
for  this  purpose,  burnt  clay  being  one  of  the  better  known  of  these  minor 
products. 

Burnt  clay. — The  following  recent  note  *  is  of  interest  in  the  present 
connection. 

"Mortar  composed  of  lime  and  burnt  clay  was  used  extensively  in 
constructing  the  Asyut  Barrage  completed  in  1902,  across  the  Nile, 
and  described  in  detail  in  a  paper  by  Mr.  George  Henry  Stephens,  M. 
Inst.  C.  E.,  to  the  institution  of  Civil  Engineers  on  March  15,  1904. 
After  being  burnt  the  clay  was  ground  and  passed  through  a  100-mesh 
sieve.  The  best  results  were  had  with  a  clay  burnt  to  a  light  terra-cotta 
color  as  compared  with  clay  burned  brick-red  and  clay  burned  dark 
red  to  purple.  The  ground  clay  was  mixed  with  slaked  lime  and  sand 
was  added  to  form  a  mortar.  The  following  are  the  results  of  long- 
time tensile  tests  made  with  various  mixtures  moulded  into  standard 
briquettes  kept  in  water  after  12  hours  in  air": 

TABLE  242. 
STRENGTH  OF  LIME — BURNT-CLAY  MORTARS. 


Mixture 
by 
Volume. 

Age  1  Year. 

Pounds  per 
Square 
Inch. 

Age  2  Years. 

Pounds  per 
Square 
Inch. 

3  clay 

1  Maximum  

400 

Maximum      

410 

2  lime 
1  clay 

J  Average  of  52  samples 
\  Maximum  

272 

305 

Average  of  56  samples.  . 
Maximum      

320 
350 

1  lime 
f  clay 

/  Average  of  38  samples. 
(Maximum 

239 
320 

Average  of  25  samples.  . 
Maximum 

291 
376 

1  lime 
£  sand 

Average  of  37  samples. 

259 

Average  of  55  samples.  . 

280 

Blast-furnace  slags. — Slags,  according  to  the  general  use  of  that 
term,  are  the  fusible  silicates  formed  during  metallurgical  operations 
by  the  combination  of  the  fluxing  materials  with  the  gangue  of  the  ore. 
The  composition  of  the  slag,  therefore,  depends  upon  the  character 
and  relative  proportions  of  the  gangue  and  the  fluxes.  The  slag  will, 
in  general,  contain  only  those  elements  present  in  either  gangue  or 
flux;  though  it  may  contain  also  a  percentage,  usually  small,  of  the 
metal  which  is  being  reduced,  and  its  composition  may,  in  some  processes, 

*  Engineering  News,  vol.  53,  p.  177.     Feb.  16,  1905. 


640  CEMENTS,  LIMES,  AND  PLASTERS. 

be  slightly  modified  by  the  presence  of  the  elements  taken  up  from  the 
fuel.  The  slags  or  " cinders"  obtained  in  refining  the  metals  differ 
from  the  normal  slags  in  that  they  may  contain  a  very  appreciable 
percentage  of  metal,  sufficient  in  many  cases  to  justify  further  treat- 
ment of  the  slag  in  order  to  recover  its  metallic  contents.  As  this  utili- 
zation of  such  slags  is  entirely  a  mejfcallurgical  operation,  they  will  not 
be  further  discussed  in  the  present  volume. 

While  many  elements  may  occur  in  slags,  those  which  are  of  universal 
or  even  common  occurrence  are  relatively  few.  fhe  slags  most  com- 
monly formed  are  silicates,  consisting  essentially  of  silica,  oxides  of  the 
alkaline  elements,  and  certain  metallic  oxides,  these  last,  with  the  ex- 
ception of  alumina,  being  usually  present  in  small  quantity  only.  In 
certain  metallurgical  operations,  however,  the  percentage  of  metallic 
oxides  may  rise  so  as  to  make  them  important  ingredients  in  the  slag. 
According  to  the  processes,  ores  or  fluxes  used,  slags  may  also  contain 
more  or  less  phosphoric  anhydride,  sulphur  and  fluorine. 

The  particular  use,  or  uses  to  which  the  slag  from  any  given  furnace 
may  be  most  profitably  put,  will  depend  upon  several  factors.  When 
considering  possible  utilizations,  the  most  important  factor  will  gen- 
erally be  found  to  be  the  chemical  composition  of  the  slag.  It  is  true 
that,  for  certain  uses,  as  for  example  highway  macadam  and  railroad 
ballast,  the  physical  condition  of  the  slag  is  of  rather  more  importance 
than  its  chemical  composition;  but  the  two  utilizations  named  are 
among  the  less  profitable,  and  are  only  to  be  considered  when  the  slag 
cannot  be  disposed  of  more  profitably.  Local  conditions,  under  which 
head  may  be  grouped  questions  of  furnace  management,  possible  markets, 
and  transportation  routes  and  charges,  will  be  found  to  be  of  great 
economic  importance.  These  factors  are,  however,  too  variable  to  be  dis- 
cussed in  the  present  volume,  with  one  exception.  The  exception  noted 
is  the  effect  of  slag  utilization  upon  the  general  furnace  management. 
The  furnace  manager  who  is  endeavoring  to  profitably  utilize  his  slag 
will  often  find  it  necessary  to  consider  how  far  he  may  economically 
go  in  changing  details  of  his  main  process  in  order  to  increase  the  value 
of  his  by-product.  This  is  particularly  the  case  where  the  slag  is  used 
for  cement. 

Blast-furnace  slags  of  certain  types  have  been  used  extensively 
in  Europe,  and  to  a  less  extent  in  the  United  States,  in  the  manufacture 
of  slag  cement.  The  following  chapters  will  therefore  be  devoted  to  a 
discussion  of  the  materials,  manufacture  and  properties  of  slag  cements. 


CHAPTER  XLII. 

SLAG  CEMENT.     REQUISITES  AND  TREATMENT  OF  THE  SLAG. 

SLAG  cement  is  at  present  by  far  the  most  important  member-  of  the 
group  of  puzzolan  cements,  so  that  its  manufacture  will  be  described 
in  some  detail. 

Summary  of  general  methods  of  manufacture.  —  Slag  cement  is  com- 
posed of  an  intimate  mechanical  mixture  of  slaked  lime  and  granu- 
lated blast-furnace  slag  of  suitable  chemical  composition;  both  mate- 
rials being  finely  pulverized  before,  during  or  after  mixing.  The  process 
of  manufacture  includes  the  granulating  and  drying  of  the  slag,  the 
slaking  of  the  lime,  the  mixing  of  these  materials,  and  the  grinding 
of  the  resulting  cement,  together  with  any  means  which  may  be  employed 
for  the  regulation  of  the  setting  time  of  the  cement. 

These  different  factors  hi  the  manufacture  will  be  described  in  the 
order  named  above.  In  the  present  chapter,  the  character  and  treat- 
ment of  the  slag  will  be  taken  up. 

Composition  of  the  Slag. 

Requisite  chemical  composition  of  slag.  —  The  slag  used  in  cement- 
manufacture  must  be  a  basic  blast-furnace  slag.  Tetmajer,  the  first 
investigator  of  slag  cements,  announced  as  the  results  of  his  experi- 
ments (a)  that  the  hydraulic  properties  of  the  slag  increased  with  the 
proportion  of  lime  contained  in  it,  and  that  slags  in  which  the  ratio 

CaO 

was  so  low  as  to  approach  unity  were  valueless  for  cement-manu- 


facture;    (6)  that,  so  far  as  the  alumina  content  of  the  slag  was  con- 
cerned, the  best  results  were  obtained  when  the  ratio   c<.^.  3  gave  a  value 


of  0.45  to  0.50;  and  (c)  that  with  any  large  increase  of  alumina  above 
the  amount  indicated  by  this  value  of  the  alumina-silica  ratio,  the  ten- 
dency of  the  cement  to  crack  (when  used  in  air)  was  increased. 

Prost,  at  a  later  date,  investigated  the  subject,  using  for  experi- 

641 


642  CEMENTS,  LIMES,  AND  PLASTERS. 

ment  several  commercial  slags  and  also  a  series  prepared  from  pure 
CaO,  Si02,  and  A1203.  He  decided  that  the  hydraulic  properties  (both 
as  regards  rapidity  of  set  and  ultimate  strength)  of  the  slag  increased 
as  the  proportions  of  lime  and  alumina  increased;  and  failed  to  find 
any  indication  that  a  high  alumina  content  causes  disintegration.  His 
best  results  were  obtained  .from  slags  having  the  compositions  re- 
spectively of  2SiO2,  A12O3,  3CaO,  arid  2SiO2,  A12O3,  4CaO. 

Mahon,  in  1893,  made  a  series  of  experiments  to  determine  the  value 
(for  cement-manufacture)  of  a  large  series  of  the  slags  produced  by 
the  furnaces  of  the  Maryland  Steel  Company:  and  found  that  the  slags 
giving  the  best  results  were  two  having  respectively  the  following  com- 
positions : 

(1)  Si02,  30%;  A1203,  17%;  CaO,  47.5%;  S,  2.38%;  and  (2)  Si02, 
25.3%;  A1203,  20.1%;  CaO,  48%;  MgO,  3.28%;  S,  2.63%. 

The  ratios  of  c,.^     and    c<.^  3,  calculated  for  these  slags  are: 


At  the  close  of  the  experiments  Mahon  recommended  that  slags 
be  used  slightly  higher  in  alumina  than  those  above  quoted. 

Composition  of  slags  actually  used.  —  The  specifications  under  which 
slag  from  the  furnaces  is  accepted  by  the  cement  department  of  the 
Illinois  Steel  Company  are: 

(1)  Slag  must  analyze  within  the  following  limits: 

Si02  +  Al203  not  over  49%;   A12O3;  from  13  to  16%;   MgO,  under 

4%. 

(2)  Slag  must  be  made  in  a  hot  furnace  and  must  be  of  a  light-gray 
color. 

(3)  Slag  must  be  thoroughly  disintegrated  by  the  action  of  a  large 
stream  of  cold  water  directed  against  it  with  considerable  force.     This 
contact  should  be  made  as  near  the  furnace  as  is  possible. 

A  series  of  over  300  analyses  of  slags  used  by  this  company  in  their 
slag  (puzzolan)  cement,  show  the  following  range  in  composition: 

Si02,  29.60  to  35.60%;  A12O3,  and  Fe2O3,  12.80  to  16.80%;  CaO, 
47.99  to  50.48%;'  MgO,  2.09  to  2.81%. 

The  requirements  of  the  Birmingham  Cement  Company  as  to  the 
chemical  composition  of  the  slags  used  for  cement  are:  that  the 
lime  content  shall  not  be  less  than  47.9  per  cent;  that  the  silica  and 
lime  together  shall  approximately  amount  to  81  per  cent;  and  that 
the  alumina  and  iron  oxide  together  shall  equal  from  12  to  15  per 
cent. 


SLAG  CEMENT.     REQUISITES  AXD  TREATMENT  OF  THE  SLAG.   643 


TABLE  243. 
ANALYSES  OF  SLAGS  USED  FOR  SLAG  CEMENT. 


Compo- 
nents. 

SiO2.. 

$&.: 

CaO.  . 
MgO.  . 

CaSO' 
SO,  . 

Middlesboro, 
England. 

Harzb'g, 
Germany 
(used  at 
Bruns- 
wick). 

Belgium. 

Bilbao,  Spain. 

Choindez,  Switzerland. 

30.00 
28.00 
0.75 
32.75 
5.25 
1.90 

31.50 

18.56 

42^22 
3.18 

30.72 
16.40 
0.43 
48.59 
1.28 
2.16 

32.51 
13.19 
0.48 
44.75 
2.20 
4.90 

32.90 
13.25 
0.46 
47.30 
1.37 
3.42 

38.00 
10.00 

26.88 
24.12 
0.44 
45.11 
1.09 
1.80 

27.33 
23.81 
O.C3 
45.83 
0.92 
1.34 
0.17 

1.67 
0.87 

2G.24 
24.74 
0.49 
46.83 
0.88 
0.59 
0.32 

1.78 
0.93 

46.00 

0.45 
2.21 
0.44 

1.34 
0.59 

tr. 
1.58 

0.53 

0.60 
1.37 

0.43 

1.13 
1.44 

0.41 

0.50 
1.68 

0.89 

S  ' 

MnO2. 
CaO.  . 

Si02.  . 
A1A  . 
SiO2.  . 

6.60 
}l.09 

JO.  93 

1.21 
0.27 

Compo- 
nents. 

Saulnes,  France. 

Marnaval  (used  at 
Donjeux). 

Pont-a- 
Mousson. 

Chicago,  111. 

SiO2. 
A1203  . 

FeO.  . 

CaO.  . 
MgO.  . 

S 

31.65 
17.00 

0.65 

47.20 
1.36 

31.50 
16.62 

0.62 
46.10 

28.35 
18.15 

1.5.0 

47.40 
2.45' 
1  ^0 

28.00 
19.5 

45.0 

1.61 
O.C9 

32.00 
22.0 
4.00  + 
MgO 
42.00 
See  FeC 

1.31 

O.C8 

32.20 
15.50 

48.14 
2.27 

1.49 

0.48 

33.10 
12.60 

49.98 
2.45 

1.51 
0.38 

31.80 
14.80 

49.74 
2.29 

1.56 
0.46 

34.30 
14.76 

48.11 
2.66 

1.40 
0.43 

MnO,. 
CaO.  . 
SiO2  .  . 
A12O3  . 
Si02.  . 

0.85 

}l.49 

J0.53 

1.46 
0.52 

1.67 
O.C4 

Analyses  of  a  number  of  slags  used  in  slag-cement  manufacture  are 
shown  in  Table  243.  The  analyses  of  foreign  slags  are  quoted  from 
various  reliable  authorities  and  the  analyses  of  the  Illinois  Steel  Com- 
pany slags  have  been  selected  from  a  large  series  published  in  the 
report  of  the  U.  S.  Army  Board  of  Engineers  to  show  the  extreme 

ranges   of  the   different   elements.     The   ratios   ~.~ 

O1U2 


,    Al2Os  , 
and   •„.„  •  have 


been  calculated  for  each  slag  and  are  shown  in  this  table. 

From  these  data  it  can  be  seen  that  the  ratio  of  alumina  to  silica 
is  carried  v$ry  high  at  Choindez,  and  is  rather  low  at  Chicago,  rela- 
tively to  most  of  the  European  plants.  It  must  be  remembered,  how- 


644  CEMENTS,  LIMES,  AND  PLASTERS. 

ever,  that  one  reason  for  carrying  a  high  alumina-silica  ratio  does  not 
apply  at  Chicago,  as  there  rapidity  of  set  is  gained  by  the  use  of  the 
Whiting  process.  Taking  these  two  plants  as  representative  of  the 
best  European  and  American  practice,  the  average  of  the  analyses 
given  shows  the  ratios  actually  used,  to  be:  Choindez,  Switzerland, 


1.71,  =  0.90;  and  Chica,  111.,  -          -l. 


These  results  may  be  compared  with  the  theoretical  ratios  advised 
by  Tetmajer,  Prost,  and  Mahon,  and  discussed  on,  a  previous  page  of 
the  present  Chapter. 

Selection  of  slags.  —  The  erection  of  a  slag-cement  plant  in  connection 
with  any  given  furnace  is  not  justified,  unless  a  sufficient  amount  of 
the  slags  usually  produced  will  fall  within  slag-cement  requirements, 
as  these  requirements  have  been  outlined  above  in  the  section  on  chem- 
ical composition  of  the  slag.  In  a  large  plant  it  will  usually  be  easy 
to  secure  a  constant  supply  of  slag  of  proper  composition  without  inter- 
fering with  the  proper  running  of  the  furnaces.  In  a  small  plant,  how- 
ever, or  in  one  running  on  a  number  of  different  ores,  such  a  supply 
may  be  difficult  to  obtain.  These  points,  of  course,  should  be  settled 
in  advance  of  the  erection  of  the  cement-plant. 

In  the  case  of  any  given  furnace  running  on  ores  and  fluxes,  which 
are  fairly  steady  in  composition  and  proportions,  the  selection  of  the 
slag  used  for  cement-making  may  be  largely  based  on  its  color,  checked 
if  necessary  by  rapid  determinations  of  lime.  The  darker-colored  slags 
are  generally  richest  in  lime,  except  when  the  depth  of  color  is  due  to 
the  presence  of  iron;  the  lighter-colored  slags  are  usually  higher  in 
silica  and  alumina.  Candlot  states  further*  in  this  connection  that 
the  slag  issuing  at  the  commencement  and  toward  the  end  of  a  discharge 
should  be  rejected  because  of  the  air-chilling  which  attends  its  slow 
movement. 

Granulating  the  Slag:  Methods  and  Effects. 

Assuming  that  a  slag  of  proper  composition  has  been  selected,  the 
first  step  in  the  actual  manufacture  of  slag  cement  will  be  the  "  granu- 
lation "  of  the  molten  slag.  Granulation  is  the  effect  produced  by 
bringing  molten  slag  into  contact  with  a  sufficient  amount  of  cold  water. 
The  physical  effect  of  this  proceeding  is  to  cause  the  slag  to  break  up 
into  porous  particles  ("slag  sand")-  Granulation  has  also  certain 
chemical  effects,  highly  important  from  an  economic  point  of  view, 
which  will  be  discussed  later. 

*  Ciments  et  chaux  hydrauliques. 


SLAG  CEMENT.     REQUISITES  AND  TREATMENT  OF  THE  SLAG.   645 

Methods  of  granulating  the  slag. — The  success  of  the  granulation 
depends  on  bringing  the  slag  into  contact  with  the  water  as  soon  as 
possible  after  it  has  left  the  furnace.  The  effects  of  the  process  will 
be  found  to  vary  with,  (a)  the  temperature  of  the  slag  at  the  point 
of  contact;  (b)  the  temperature  of  the  water;  (c)  the  amount  of  water 
used,  and  (d)  its  method  of  application. 

Taking  up  the  last  point  first  it  may  be  noted  that  two  general 
methods  of  application  of  the  water  have  been  used.  In  the  first  method 
the  stream  of  slag,  as  it  issued  from  the  furnaces,  was  struck  by  a  jet 
of  steam  under  pressure.  This  method,  which  was  used  at  one  time 
in  slag-cement  plants  in  the  Middlesboro  district,  England,  had  the 
effect  of  blowing  the  slag  into  fine  threads  with  attached  globules.  It 
is,  in  fact,  much  the  same  as  the  process  still  used  in. the  manufacture 
of  mineral  wool.  From  an  economic  point  of  view  it  had  the  distinct 
advantage  of  putting  the  slag  in  a  condition  in  which  it  was  easily  pul- 
verized by  the  grinding-machinery ;  but  it  had  certain  inconveniences, 
and  has  been  almost  or  entirely  superseded  by  the  method  now  to  be 
mentioned. 

The  second  way  in  which  the  water  may  be  applied  is  to  allow  the 
stream  of  slag  as  it  issues  from  the  furnace  to  fall  into  a  trough  contain- 
ing a  rapidly  flowing  stream  of  cold  water.  Care  must  be  taken  that 
the  fall  into  the  trough  is  not  too  great,  and  that  the  stream  of  water 
is  deep  enough  and  fast  enough,  for  otherwise  the  slag  will  acquire 
sufficient  momentum  in  its  fall  to  solidify  in  a  mass  on  the  bottom  of 
the  trough .  This  method  is  in  use  at  all  slag-cement  plants  of  the  present 
day,  being  occasionally  modified  by  the  use  (either  in  addition  to  or 
in  place  of  the  flowing  stream  of  water  in  the  trough)  of  a  jet  of  water 
playing  on  the  slag  before  it  strikes  the  trough. 

The  following  two  examples,  taken  from  present-day  practice  at 
American  slag-cement  plants,  will  serve  to  indicate  two  methods,  dif- 
fering in  minor  details  only,  of  slag  granulation. 

At  the  first  plant  the  furnaces  are  located  on  an  embankment 
,  about  8  feet  above  and  20  feet  away  from  a  standard  gauge-switch 
track.  A  rectangular  trench  about  1  foot  in  width  is  dug  from  the 
furnace  to  near  the  edge  of  the  embankment.  Here  a  section  of  semi- 
circular sheet-iron  troughing,  12  to  15  inches  in  diameter  and  about  10 
feet  in  length,  meets  the  trench.  The  inner  end  of  the  trough  is  fixed, 
and  is  at  such  a  level  that  the  bottom  of  the  trough  is  about  6  inches 
below  the  bottom  of  the  trench.  The  outer  end  of  the  trough  is  free 
and  supported  by  wire  ropes  so  that  it  can  be  readily  swung  into 
position  over  a  box  car  on  the  switch  track  below. 


646  CEMENTS,  LIMES,  AND  PLASTERS. 

As  already  noted,  the  bottom  of  the  earthen  trench  is  about  6  inches 
above  the  bottom  of  the  iron  trough.  This  is  done  to  tillow  the  inser- 
tion at  this  end  of  the  trough  of  a  3-inch  water-pipe.  Slag  from  the 
furnace  flows  through  the  trench  and  into  the  trough,  which  is  set  at 
an  inclination  of  about  1  inch  in  10.  Water  is  injected  through  the 
3-inch  pipe,  under  10  or -15  feet  hpad,  into  the  trough.  If  enough 
water  is  used,  the  slag  will  be  granulated  as  soon  as  it  enters  the 
trough,  and  will  be  readily  carried  down  it  into  the  car  below,  rarely 
flowing  with  a  greater  depth  than  6  inches  in  the  trough.  If  insuffi- 
cient water  is  used  the  slag  puffs  up  and  fills  the  trough,  so  that  the 
slag-mass  has  to  be  broken  into  with  an  iron  rod  and  pushed  along. 

The  car  into  which  the  slag  flows  is  provided  with  four  3-inch  holes 
in  its  sides,  to  allow  the  surplus  water  to  escape. 

At  another  slag-cement  plant  recently  visited  by  the  writer,  the 
granulated  slag  is  caught  in  cylindrical  masonry  tanks,  15  feet  in 
diameter  and  10  feet  in  depth.  The  stream  of  molten  slag  flows  from 
the  furnace  to  and  over  the  edge  of  the  tank  and  through  a  semi-circular 
trough  about  10  inches  in  diameter,  which  enters  the  tank  at  its  top 
rim  and  projects  G  inches  over  the  edge.  About  6  inches  below  the 
bottom  of  this  trough  a  pipe,  carrying  cold  water  under  slight  pressure, 
enters  the  tank,  projecting  into  it  for  4  inches.  This  pipe  is  3 
inches  in  diameter  for  most  of  its  length,  but  the  portion  projecting 
into  the  tank  is  flattened  so  as  to  give  an  orifice  4  or  5  inches  wide 
and  about  half  an  inch  high.  The  stream  of  slag,  flowing  slowly  along 
the  trough  and  over  the  edge  of  the  tank,  is  struck  by  the  jet  of  cold 
water  from  the  pipe,  and  is  granulated.  The  granulated  slag  is  taken 
from  the  tank  by  bucket  elevators  running  continuously. 

Effects  of  granulating  the  slag — The  physical  effect  of  causing  hot 
slag  to  come  in  contact  with  cold  water  is  to  break  the  slag  up  into 
small  porous  particles.  As  this  materially  aids  in  pulverizing  the  slag, 
it  is  probable  that  granulation  would  be  practiced  on  this  account 
alone.  But  as  a  matter  of  fact,  granulation  has  in  addition  to  its  purely 
physical  result  two  important  chemical  effects.  One  is  to  make  th£ 
slag,  if  it  be  of  suitable  chemical  composition,  energetically  hydraulic; 
the  other  is  to  remove  a  portion  of  the  sulphides  contained  in  the  slag 
in  the  form  of  hydrogen  disulphide. 

Le  Chatelier  states  that  the  hydraulic  properties  of  granulated  slag 
are  due  to  the  presence  of  a  silico-alumino  ferrite  of  calcium  correspond- 
ing in  composition  to  the  formula  3CaO,  A12O3,  2SiO2.  This  com- 
pound appears  also  in  Portland  cements,  but  in  them  it  is  entirely  inert, 
owing  to  the  slow  cooling  it  has  undergone.  When,  however,  as  in 


SLAG  CEMENT.     REQUISITES  AND  TREATMENT  OF  THE  SLAG.  647 


the  case  of  granulated  slags,  it  is  cooled  with  great  suddenness,  it  becomes 
an  important  hydraulic  agent.  When  so  cooled  "it  is  attackable  by 
weak  acids  and  also  by  alkalies.  It  combines  particularly  with  hydrated 
lime  in  setting,  and  gives  rise  to  silicates  and  aluminates  of  lime  iden- 
tical with  those  which  are  formed  by  entirely  different  reactions  during 
the  setting  ,of  Portland  cement.  It  is  upon  this  property  that  the  manu- 


6000 
4000 
2000 

0 

,  ^v 

l^-^-< 

X 

£L 

$2&- 

to^- 



• 

^         — 

—  e  — 

a 

OL 
< 

D 

/ 

/>— 

^_StA£ 

TO_2_U< 
'    o  3  L| 

WE  ^ 
ME  ~L 

)  

co    d 

ffi    <* 

/\ 

>°  — 

—  0 

Q.          Qj 

CO 
D 

z 

GRANULA 
NOT  GRA 

NULA 

0 

a. 

_-o-- 

_  

.-—• 

-•  < 

iE-fS=S 

==••=^1 

~~ 

=  =r=^= 

)       w          70                 140                210                 280                350 

AGE    IN    DAYS 

COMPRESSION 
FIG.  159.* — Effect  of  granulating  slag.     (Tetmajer.) 


70  140  210 

AGE    IN    DAYS 

TENSION 
FIG.  160.* — Effect  of  granulating  slag. 


280 


350 


(Tetmajer.) 

facture  of  slag  cements,  which  assumes  daily  greater  importance,  is 
based  ". 

Increased  hydraulicity  due  to  granulation.  —  The  striking  increase  in 
the  hydraulic  properties  of  the  slag  when  it  is  granulated  was  well 
brought  out  by  Frost's  investigations.  The  following  table  (244)  ;  giving 
the  results  of  tests  of  tensile  and  compressive  strength  of  briquettes  of 

*  From  Johnson's  "  Materials  of  Construction",  p.  190. 


648 


CEMENTS,  LIMES,  AND  PLASTERS. 


both  granulated  and  ungranulated  slag,  as  determined  by  Prost,  is  of 
interest  in  this  connection.  The  results  of  other  tests,  by  Tetmajer, 
are  shown  diagrammatically  in  Figs.  159  and  160. 

TABLE  244. 
STRENGTH  OF  GRANULATED  AND  UNGRANULATED  SL\O.     (PROST.) 


Proportions  of  Mixture  by  Weight. 

V* 

Resistance  in  Kilograms  per  Square  Centimeter. 

28  Days. 

84  Days. 

210  Days. 

360  Days. 

a 

Compression. 

g 
•S 

1 

Compression. 

Tension. 

Comp  revision  . 

Tension.^ 

Compression. 

33  parts  lime,  100  parts  slag: 
Granulated                      .  . 

33.7 

0 

32.1 
0 

27.6 
0 

259.9 
0 

233.7 

0 

205.2 
0 

43.5 
5.4 

38.1 
5.4 

34.3 
0 

377.5 

0 

308.2 
0 

248.9 
0 

46.4 
10.7 

40.5 
10.5 

•  38.9 

7.6 

440.5 
50.5 

326.7 
54.1 

267.8 
47.6 

44.4 
13.8 

35.3 
13.3 

38.1 
10.8 

438.7 
59.9 

350.9 
62.4 

253.1 
63.8 

Not  granulated 

66  parts  lime,  100  parts  slag: 
*       Granulated        

Not  granulated  
100  parts  lime,  100  parts  slag: 
Granulated 

Not  granulated 

Desulphurization  due  to  granulation.— When  molten  slag  is  poured 
into  water,  a  very  large  proportion  of  the  sulphur  contained  in  the 
slag  is  carried  off  by  the  water.  The  extent  to  which  the  desulphuriz- 
ing of  the  slag  is  secured  by  the  simple  method  of  granulating  is  shown 
by  the  following  result  from  actual  practice  at  the  slag  brick  works  at 
Kralovedvoor,  Bohemia.  Here  the  slag  is  granulated,  just  as  in  slag- 
•cement  works,  by  running  it  into  flowing  cold  water.  Examination  * 
-of  the  water  used  showed  that  it  had  increased  in  temperature  from 
14i°  C.  to  about  56°  C.,  and  that  it  carried  in  10,000  parts  the  follow- 
ing parts  of  mineral  matter  in  solution: 

SiO2 0.426 

CaSO4 0.749 

FeSO4 0 . 108 

MgSO4 0.448 

NaaSO4 0 . 178 

NaCl 0 .038 

Na2SiO2 0.693 

CaS 0 .271 

H^ 0 . 047 

2.958 


*  Engineering  and  Mining  Journal,  April  16,  1898. 


SLAG  CEMENT.     REQUISITES  AND  TREATMENT  OF  THE  SLAG.  649 

Drying  the  Slag. 

The  slag  as  it  is  brought  to  the  cement  mill  from  the  granulating 
tanks  carries  from  15  to  over  40  per  cent  of  water  absorbed  during 
granulation.  As  will  be  noted  later  attempts  have  been  made  to 
utilize  this  contained  water  in  the  slaking  of  the  lime,  but  these 
attempts  have  hitherto  proved  unsuccessful.  As  the  manufacture 
is  at  present  conducted,  therefore,  the  large  percentage  of  water 
carried  by  the  slag  is  of  no  service,  and  in  order  to  get  good  results 
from  the  grinding  machinery  the  water  must  be  removed  as  completely 
as  possible  before  pulverization  is  attempted. 

Before  describing  the  various  types  of  driers  in  use,  a  few  words 
on  the  general  problem  may  be  serviceable.  The  slag  may  carry,  as 
above  noted,  from  15  to  over  40  per  cent  of  water,  varying  with  the 
method  of  granulation,  the  fineness  of  grain,  etc.  In  test  runs  slag 
can  be  thoroughly  granulated  without  the  use  of  more  than  10  to  15 
per  cent  of  water,  but  in  actual  practice  it  will  usually  be  found  that 
the  granulated  slag  carries  from  30  to  45  per  cent.  As  the  slag  must 
be  reduced  to  extreme  fineness  it  is  necessary  that  this  moisture  be 
reduced  as  much  as  possible.  With  a  well-conducted  rotary  drier  it 
is  possible  to  economically  reduce  the  percentage  of  moisture  in  the 
dried  product  to  about  one-fourth  of  one  per  cent. 

The  temperature  to  which  the  product  is  carried  in  drying  is  not 
a  matter  of  serious  moment  so  long  as  it  does  not  pass  the  point  at 
which  the  slag  begins  to  re-fuse.  Theoretically,  of  course,  it  is  neces- 
sary only  to  carry  the  temperature  above  212°  F.,  but  in  practice  it  is 
economically  impossible  to  keep  it  as  low  as  this.  It  may  be  carried 
as  high  as  a  dull-red  heat  without  injury  to  the  slag.  Indeed,  it  is 
probably  the  case  that  drying  at  relatively  high  temperatures  improves 
the  hydraulic  properties  of  the  slag,  rather  than  otherwise,  as  it  is  well 
known  that  the  natural  puzzolanic  materials  are  improved  by  roasting. 
It  would  not,  therefore,  be  a  matter  of  surprise  if  drying  the  slag  at  a 
higher  temperature  than  is  actually  necessary  should  result  in  mate- 
rially accelerating  the  set  of  the  resulting  cement  and  also  in  increasing 
the  strength  of  briquettes  made  from  it. 

The  Ruggles-Coles  drier  (see  Fig.  161)  consists  of  two  concentric 
hollow  cylinders  bolted  together  and  revolving  on  an  axis  slightly  inclined 
from  the  horizontal.  The  outside  cylinder  is  made  of  steel  plates,  the 
longitudinal  seams  having  butt  joints  with  inside  lapping  straps.  The 
inner  cylinder,  which  is  also  made  of  steel,  is  connected  with  the  outer 
cylinder  at  its  middle  by  heavy  cast-iron  arms  A  solidly  riveted  to 


650 


CEMENTS,  LIMES    AND   PLASTERS. 


both  cylinders,  while  the  cylinders  are  further  connected  at  each  end 
by  two  sets  of  adjustable  or  swinging  arms  B,  which  prevent  the 
joints  being  affected  by  the  expansion  or  contraction  of  the  cylinders. 
At  the  head  or  upper  end  the  inner  cylinder  projects  beyond  the  outer 
cylinder,  passing  into  a  stationary  head  or  air  chamber  E  to  the  hot 
air  flue  D  of  the  furnace '•"<£•  with  which  it  is  connected.  At  the  lower 
or  discharge  end  is  another  stationary  head  E  forming  an  air  chamber, 
through  an  opening  in  the  bottom  of  which  the  dried  material  is  dis- 
charged. This  head  is  supplied  with  a  damper  »to  regulate  the  tem- 
perature, which  gives  perfect  control. 

The  cylinders  are  set  at  an  inclination  of  about  f  inch  to  the  foot. 
The  outer  cylinder  is  secured  to  two  heavy  rolled  steel-bearing  rings, 


FIG.  161. — Ruggles-Coles  drier. 

which  rest  and  revolve  upon  eight  bearing  wheels  supported  by  oscil- 
lating arms  or  rockers.  The  lateral  motion  of  the  cylinder  is  taken 
up  by  four  thrust  wheels.  The  drier  is  revolved  by  a  cast  gear  H 
secured  to  the  outer  cylinder,  and  this  is  driven  by  a  shaft  and  pinion 
K  extended  beyond  the  end  of  the  machine  and  supported  in  two 
babbitted  journal  boxes  fitted  to  the  frame.  The  entire  machine  is 
fitted  and  secured  to  a  heavy  frame  of  8-inch  I  beams  braced  and 
framed  together  and  usually  set  on  a  concrete  foundation.  The  exhaust 
fan  is  placed  where  most  convenient  to  drive,  and  is  connected  with  the 
outer  cylinder  by  a  suitable  flue  L.  The  furnace  G  is  built  inde- 
pendent of  the  rest  of  the  drier,  and  is  connected  with  the  head  end  of 
the  inner  cylinder  by  an  iron  flue  D  built  with  fire-brick.  A  specially 
designed  burner  is  substituted  for  the  furnace  when  oil,  gas,  or  powdered 
coal  are  to  be  used. 

The  heated  air  passes  through  the  inner  cylinder  (which  is  shown 
by  the  dotted  lines  in  the  illustration)  and  returns,  between  the  inner 
and  outer  cylinders,  to  the  fan.  The  direction  of  the  hot-air  current 
is  shown  by  arrows.  The  wet  raw  material  is  fed  into  the  space  between 
the  inner  and  outer  cylinders  through  a  spout  C  in  the  stationary 


SLAG  CEMENT.     REQUISITES  AND  TREATMENT  OF  THE  SLAG.   651 


head  at  the  upper  end  of  the  drier.  The  material  is  picked  up  by 
buckets  or  carriers  fastened  to  the  inner  surface  of  the  outer  cylinder, 
and  is  carried  partly  around  during  the  rotation  of  the  drier.  On 
dropping  from  these  buckets  it  is  caught  by  nights  fastened  to  the  outer 
surface  of  the  inner  cylinder.  These  flights  carry  the  material  partly 
around  and  then  drop  it  on  the  outer  cylinder,  when  the  cycle  of  opera- 
tions commences  again.  While  the  movements  of  the  material  are 
occurring,  it  is  being  dried  both  by  the  heated-air  current  which  flows 
through  the  space  between  the  two  cylinders,  and  by  contact,  with  the 
warm  outer  surface  of  the  inner  cylinder;  and  it  is  also  being  carried 
slowly  toward  the  lower  or  discharge  end  of  the  machine. 

The  following  table  shows  working  results  obtained  in  the  use  of 
the  Ruggles-Coles  drier  on  blast-furnace  slag  at  various  slag-cement 
plants : 

TABLE  245. 
WORKING  RESULTS  OF  RUGGLES-COLES  DRIER. 


User. 

Number 
of 
Driers. 

Original 
Percentage 
Moisture. 

Final 
Percentage 
Moisture. 

Water 
Evaporated 
per  Hour. 

Knickerbocker  Cement  Co. 
Maryland  Cement  Co.  .... 
Birmingham  Cement  Co.  .  . 
Southern  Cement  Co.  . 

1 
2 
2 
2^ 

41.82 
20.32 
45 
40 

0.29 
0.25 

4401  Lbs. 
4114     " 
4181     " 
4707     " 

Stewart  Cement  Co  

3 

12  85 

2272     " 

User. 

Dry  Material 
Delivered 
pefSHour. 

Coal  Used 
per  Hour. 

Water  Evaporated 
per  Pound 
of  Coal. 

Knickerbocker  Cement  Co. 

6,399  Lbs. 

560  Lbs. 

7  87  Lbs. 

Maryland  Cement  Co    ... 

16,173    " 

542     " 

7  59    " 

Birmingham  Cement  Co.  . 

4,987    " 

537     " 

7  60    " 

Southern  Cement  Co  

7,061     " 

550     " 

8  56    " 

Stewart  Cement  Co 

15  408     " 

334     " 

6  80    " 

The  Hoist  drier  is  used  at  Donjeux  and  Mallstadt,  and  consists 
essentially  of  a  sheet-iron  cylinder  9  meters  long  and  0.8  meter  in  diam- 
eter, into  which  the  slag  is  fed  automatically  by  a  screw  feed.  In  the 
cylinder  a  helical  screw  revolves  on  a  hollow  central  shaft,  causing  the 
slag  to  advance  slowly  through  the  cylinder.  The  fireplace  is  below 
and  near  one  end  of  the  cylinder  and  the  heat  is  caused  to  pass  under 
the  cylinder  to  the  other  end,  thence  through  the  hollow  shaft  to  the 
stack  in  a  direction  contrary  to  that  in  which  the  slag  is  moving.  The 
cylinder  is  protected  from  the  direct  flame  by  brickwork.  This  appa- 


652 


CEMENTS,  LIMES,  AND  PLASTERS. 


ratus  dries  from  7  to  8  metric  tons  of  slag  per  day  with  a  coal  consump- 
tion of  about  5  per  cent  of  the  weight  of  slag  dried. 

At  Vitry,  France,  a  simple  and  effective  non-rotary  drier,  operated 
by  gravity,  is  employed,  plan  and  section  of  which  is  given  in  Fig.  162. 
It  consists  of  drying  compartments  (each  of  which  is  lettered,  a,  6,  c,  dr 
in  the  plan),  arranged  about  a  central  flue  (c,  d,  c,  d  in  plan),  through 
which  passes  the  heated  gases  from' a  furnace.  The  central  flue  is  1  m. 


FIG.  162.— Vitry  slag-drier. 

square;  the  drying  compartments  0.5X1  m.  in  area,  and  both  are 
7  m.  in  height.  Each  of  the  drying  compartments  contains  10  sheet- 
iron  plates  (of  which  only  six,  E,  are  shown  in  each  compartment  of 
the  section).  These  plates  are  inclined  and  so  arranged  that  the  wet 
slag,  shoveled  in  at  the  top  of  each  compartment,  descends  by  gravity 
and  finally  issues  from  the  lowest  plate  in  the  heaps  F,  from  which 
it  is  shoveled  and  sent  to  the  grinding  mills.  According  to  Prost,  a 
drier  of  this  type  and  size  will  dry  from  12  to  15  metric  tons  of  slag 
per  working  day.  From  6  to  6.5  Ibs.  of  coke  are  necessary  to  dry  each 
100  Ibs.  of  slag. 

Tower  driers,  resembling  those  used  at  one  or  two  American  Portland 
cement  plants,  could  of  course  be  used  in  drying  slag.  At  present, 
however,  every  slag-cement  plant  in  the  United  States  uses  rotary 
driers. 


CHAPTER  XLIII. 
SLAG  CEMENT:    LIME,  MIXING  AND  GRINDING. 

AFTER  the  slag  has  been  granulated  and  dried,  as  described  in  the 
preceding  chapter,  it  must  be  mixed  with  a  carefully  slaked  lime,  in 
proper  proportions,  and  the  mixture  must  be  finely  ground.  These 
points  will  be  taken  up  first  in  the  present  chapter,  after  which  data 
on  the  general  processes  and  costs  of  slag-cement  manufacture  will  be 
presented. 

Composition  and  selection  of  the  lime. — The  lime  used  for  admix- 
ture with  the  slag  may  be  either  a  quicklime  (common  lime)  or  a  hydraulic- 
lime.  In  usual  American  practice,  and  also  at  most  European  plants, 
a  common  or  quicklime  is  used.  At  a  few  American,  French,  and 
German  plants,  however,  limes  which  have  more  or  less  hydraulic 
properties  are  employed.  Prost  has  carried  on  experiments  touching 
this  point  and  decided  that  the  use  of  a  hydraulic  lime  did  not  notice- 
ably increase  the  tensile  strength  of  the  resulting  cement,  but  that  it 
did  increase  the  value  of  the  product  in  another  way.  This  incidental 
advantage  is  that  slag  cements  made  by  using  hydraulic  lime  are  less 
liable  to  fissure  and  disintegrate  when  used  in  air  or  in  dry  situations 
than  cement  in  which  common  quicklime  is  used.  As  above  noted, 
this  method  of  improving  the  product  has  been  tried,  to  the  writer's 
knowledge,  at  only  a  few  of  the  American  plants.  At  Konigshof,  Ger- 
many, the  general  practice  at  which  plant  is  described  on  page  662,  a 
somewhat  hydraulic  lime  is  used,  whose  analysis  will  serve  as  fairly 
representative  of  materials  of  this  type,  though  most  hydraulic  limes 
would  run  considerably  higher  in  silica  and  alumina. 

ANALYSIS  OF  HYDRAULIC  LIME,  KONIGSHOF,  GERMANY. 

Per  Cent. 

Silica  (SiO2) . . . 12.421 

Alumina  (A12O3) ........     2 . 620 

Iron  oxide  (Fe2O3) .-., 0 .883 

Manganese  oxide  (MnO2) „ „ . . .     tr. 

Lime  (CaO) . . 81 .646 

Magnesia  (MgO) . . 1 . 751 

Soda  (Na,O) 0  „ 0.211 

Carbon  dioxide  (CO2) 0. 194 

Moisture  (H2O).  .......  0 ..  0 0.425 

653 


654 


CEMENTS,  LIMES,  AND  PLASTERS. 


The  following  analyses  are  of  limes  used  at  different  slag-cement 
plants  in  the  United  States: 

TABLE  246. 
ANALYSES  OF  LIMES  USED  IN  AMERICAN  SLAG-CEMENT  PLANTS. 


'•• 

•1. 

7*2. 

3. 

4. 

5. 

6. 

Silica  (SiO2)     

3  24 

3  50 

1  62 

10  20 

0  78 

1  38 

Alumina  (A12O3) 

1  ,  n 

Iron  oxide  (Fe2O3) 

J4.26 

3.92 

2.62 

3.60 

0.52 

0.62 

Lime  (CaO) 

81  92 

83  20 

82  40 

81  33 

98  40 

97  80 

Magnesia  (MgO) 

n   d 

n  d 

n   d 

1  17 

0  10 

0  18 

Of  the  analyses  above  tabulated,  it  will  be  seen  that  Nos.  1  to  4 
inclusive  are  of  the  semi-hydraulic  type  whose  value  has  been  noted. 
Analyses  5  and  6,  on  the  other  hand,  are  representative  of  the  very 
pure  limes  used  at  most  slag-cement  plants. 

Burning  the  lime. — As  a  matter  of  convenience,  and  also  to  reduce 
freight  charges,  the  limestone  is  burned  near  the  quarry.  The  subject 
of  burning  the  lime  requires  only  brief  mention  here,  as  it  involves  no 
points  of  particular  interest  or  novelty.  Only  two  minor  details  demand 
notice,  as  affecting  the  value  of  the  cement.  The  first  is,  that  the  lime 
should  be  burned  as  thoroughly  as  possible,  for  unburned  lumps  of  lime- 
stone are  absolutely  valueless  to  the  cement-manufacturer,  and  must 
be  removed  before  mixing  with  the  slag.  The  second  point  to  be  noticed 
is,  that  the  lime  should  be  shipped  t$  the  cement-plant  as  soon  as  pos- 
sible after  it  is  burned,  in  order  to  prevent  any  considerable  proportion 
of  it  from  air-slaking.  Air-slaked  particles,  while  not  absolutely  inert, 
are  still  of  little  value  to  the  cement. 

Slaking  the  lime. — The  granulated  slag  as  it  comes  to  the  mill  from 
the  tanks  to  which  it  is  carried  in  granulating  it  carries  a  very  large 
percentage  of  water.  The  amount  of  water  carried  will  vary  in  prac- 
tice at  different  plants  between  25  and  50  per  cent  as  limits.  Early 
in  the  history  of  slag-cement  manufacture  attempts  were  made  to 
utilize  this  surplus  water.  To  this  end  the  wet  slag  was  mixed  with 
dry  unslaked  lime,  the  expectation  being  that  the  water  in  the  slag 
would  serve  to  slake  the  lime.  In  practice,  however,  it  was  soon  found 
that  this  plan  was  not  successful.  The  lime  was  only  partially — and 
very  irregularly — slaked,  and  the  mixture  was  not  left  in  such  a  con- 
dition as  to  be  economically  handled  by  the  pulverizing  machinery. 
In  present-day  practice,  therefore,  the  lime  is  slaked  previous  to  being 
mixed  with  the  slag. 


SLAG  CEMENT:  LIME,  MIXING  AND  GRINDING.  655 

Sieving  and  grinding  the  lime. — If  lime  has  been  thoroughly  burned 
and  carefully  slaked  it  will  all  be  in  the  form  of  a  very  fine  powder,  much 
finer  than  can  be  obtained  by  any  economically  practicable  grinding- 
machinery.  In  practice,  however,  it  will  be  found  that  after  slaking 
the  lime  has  not  all  fallen  to  powder,  but  still  contains  a  certain  pro- 
portion of  hard  lumps.  The  degree  of  carefulness  with  which  the  burn- 
ing and  slaking  have  been  conducted  may  be  roughly  judged  by  observ- 
ing the  relative  proportions  of  lumps  and  powder. 

The  material  remaining  as  lumps  is  of  three  different  kinds.  First, 
and  in  greatest  proportion,  are  fragments  of  limestone  which  have  not 
been  thoroughly  burned  in  the  kiln.  Such  unburned  pieces  would 
be  inert  if  used  in  the  cement.  Second,  part  of  the  lumps  represent 
fragments  of  limestone  which  have  been  overburned  in  the  kiln  and 
have,  therefore,  partly  clinkered.  This  is  particularly  likely  to  happen 
if  the  limestone  contained  any  large  proportion  of  silica  or  alumina.  These 
partly  clinkered  lumps,  being  really  poor-grade  natural  cements,  can 
if  pulverized  do  no  particular  harm  to  the  slag  cement,  but  on  the  other 
hand  they  cannot  do  as  much  good  as  an  equal  amount  of  lime.  The 
third  kind  of  material  that  may  be  present  in  lump  form  consists  of 
fragments  of  well-burned  lime,  which,  through  accident  or  carelessness, 
have  not  been  well  slaked.  These  lumps  of  quicklime  would,  if  incor- 
porated in  the  cement,  be  actively  injurious. 

The  preceding  description  and  discussion  of  the  three  classes  of  mate- 
rial which  are  likely  to  remain  as  lumps  in  the  slaked  lime  have  been 
intentionally  made  detailed  in  order  to  point  out  an  error  in  practice 
committed  occasionally  at  slag-cement  plants.  It  has  been  seen  that 
the  materials  composing  these  lumps  are  of  such  a  character  as  to  be 
either  useless  or  actively  injurious  if  used  in  a  slag  cement.  It  should 
be  obvious,  therefore,  that  the  only  rational  method  of  treatment  is 
to  sieve  the  slaked  lime  and  to  reject  entirely  all  the  material  failing 
to  pass  through  the  sieve.  This  is  the  best  practice  and  the  method 
usually  followed.  Occasionally,  however,  urged  by  a  false  idea  of 
economy  or  by  inaccurate  reasoning,  the  manufacturer  saves  the  mate- 
rial failing  to  pass  the  sieve,  crushes  it,  and  adds  it  to  the  cement  at 
a  later  stage  in  the  manufacture. 

Proportions  of  lime  and  slag. — Prost,  in  consequence  of  his  experi- 
ments with  various  proportions  of  lime,  advocated  the  proportion,  to 
secure  the  best  results,  of  from  35  to  40  parts  of  lime  to  100  parts  of 
slag.  He  also  stated  that  the  amounts  of  lime  used  in  actual  practice, 
for  each  100  Ibs.  of  slag  were:  at  Choindez,  40  to  45  Ibs.;  at  Donjeux, 
40 Ibs.;  at  Brunswick,  33  Ibs.,  and  at  Cleveland,  33  Ibs.  Mahon,  in  report- 


656  CEMENTS,  LIMES,  AND  PLASTERS. 

ing  his  experiments  for  the  Maryland  Steel  Company,  states  that  the 
best  results  were  secured  by  the  use  of  25  parts  of  lime  to  100  parts  of 
slag,  by  weight.  At  another  American  plant  the  proportions  used  are 
20  Ibs.  lime  to  100  Ibs.  slag.  In  the  manufacture  of  slag  brick,  which 
is  in  reality  merely  a  branch  of  the  slag-cement  industry,  the  amount 
of  lime  added  may  fall  as  law  as  10  Ibs.  to  100  Ibs.  of  slag. 

These  rules  are,  of  course,  purely  empirical;  and  it  is  time  that  some 
better  method  of  calculating  the  mixture  should  be  presented.  ThL: 
of  course,  can  be  accomplished  by  the  use  of  the  same  device  which 
has  been  previously  discussed  in  connection  with"  hydraulic  limes, 
natural  cements,  and  Portland  cements. 

Calculating  the  mixture. — If  we  determine  the  Cementation  Index  * 
of  a  series  of  representative  American  slag  cements,  such  as  is  given 
on  page  667,  we  will  find  that  the  value  obtained  ranges  from  about 
1.6  to  1.9 

Accepting  these  values  as  fairly  typical  the  information  thus  gained 
can  be  employed  in  devising  a  method  for  determining  accurately  the 
proportions  in  which  any  given  slag  should  be  mixed  with  any  given 
lime  in  order  to  secure  a  good  slag  cement. 

Operation  1.  Slag. — Multiply  the  percentage  of  silica  in  the  slag  by 
2.8,  the  alumina  by  1.1,  and  the  iron  oxide  by  0.7;  add  all  the  products 
together.  From  the  sum  subtract  the  percentage  of  lime  in  the  slag 
plus  1.4  times  the  magnesia.  Call  the  result  "m  ". 

Operation  2.  Limestone.— Multiply  the  percentage  of  silica  in  the 
unslaked  quicklime  by  2.8,  the  alumina  by  1.1,  and  the  iron*  oxide  by 
0.7,  and  add  the  products  together.  Subtract  this  sum  from  the  total 
percentage  of  lime  (CaO)  plus  1.4  times  the  magnesia.  Call  the  result 
"n". 

Operation  3.  Divide  lOOXm.by  1.7 Xn.     The  quotient,  -—= — ,  will 

equal  the  number  of  parts  of  quicklime  to  be  used  for  each  100  parts 
of  slag.  The  factor  by  which  n  is  to  be  multiplied  is  here  taken  as 
1.7,  a  very  satisfactory  value*.  Values  as  low  as  1.6  and  as  high  as 
1.9  would,  however,  give  the  proportions  used  in  practice  at  various 
plants. 


*  As  previously  explained  in  detail  (pp.  170-171),  the  Cementation  Index  is 
the  value  obtained  from  the  formula 

(2.8  X  percentage  silica)  +  (1. 1 X  percentage  alumina) 

Cementation  Index = +  (0. 7 X percentage  iron  oxide) ;_^^ 

(Percentage  lime)  +  (1.4  X  percentage  magnesia) 


SLAG  CEMENT:  LIME,  MIXING  AND  GRINDING.  657 

Example. — Assume  that  the  two  raw  materials  have  the  following 
composition : 

Slag.  Limestone 

Silica  (SiO2) 32.2  1.8 

Alumina  (A12O3) 12.0  1.2 

iron  oxide  (FeO,  Fe2O3) 0.6  0.4 

Lime  (CaO) 48.1  94.0 

Magnesia  (MgO) 2.3  1.2 

Operation  1.  Slag. 

Silica  X2. 8  =  32. 2X2. 8=  90.16 

Alumina  XL 1=12. 0X1.1=  13.20 

Iron  oxide  X0.7  =   0.6X0.7=  0.42 


103.78 

Lime  Xl.O  =48.1X1.0=   48.1 

Magnesia     Xl.4=   2.3X1.4=     3.22 

51.32 
103. 78-51. 32  =ra  =  52. 46 

Operation  2.  Lime. 

Silica  X2.8=   1.8X2.8=     5.04 

Alumina       Xl.l=    1.2X1.1=      1.32 
Iron  oxide  X0.7=   0.4X0.7=     0.28 

6.64 

Lime  Xl.O  =94.0X1.0  =   94.00 

Magnesia     Xl.4=    1.2X1.4=     1.68 

95.68 
95.68-6.64  =  n  =  89.04 

Operation  3. 

100  w     100X52.46      5246       [34.6  =  parts  unslaked  quicklime  for  each 


I. In      1.7X89.04     151.4      \      100  parts  dry  slag. 

Pulverizing  and  mixing. — The  greatest  differences  in  practice  exist 
in  the  processes  for  grinding  and  mixing  the  slag  and  lime.  The  state- 
ment has  been  made  in  several  publications  that  the  differences  in 
hardness  between  dry  granulated  slag  and  slaked  lime  is  so  great  that 
it  is  impracticable  to  pulverize  them  together  in  a  continuously  operated 
mill.  A  number  of  plants,  therefore,  have  installed  small  discontinuous 
mills,  each  of  which  is  charged,  locked,  operated  for  a  sufficient  time  to 
pulverize  both  constituents  of  the  mixture,  and  discharged.  The  dis- 
advantages of  this  intermittent  system  are  obvious  and  it  seems  especially 
unfitted  for  American  conditions.  The  statement  that  no  continu- 
ously operated  mill  was  able  to  handle  the  mixture  seemed  inherently 


658  CEMENTS,  LIMES,  AND  PLASTERS. 

improbable,  in  view  of  the  great  variety  of  material  successfully  handled 
by  the  modern  ball  and  tube  mills  when  operated  continuously  in  Port- 
land-cement practice.  Several  years  ago  I  referred  the  question  to  a 
leading  firm  of  manufacturers  and  was  informed  that  nothing  in  their 
experience  justified  the  unfavorable  conclusion,  and  that  their  con- 
tinuously operated  tube  mills  hacU  successfully  pulverized  mixtures 
of  slag  and  lime.  It  seems  probable  that  the  most  economical  prac- 
tice would  be  to  send  the  dried  slag  through  a  small  crusher,  Griffin 
mill,  or  ball  mill,  mixing  the  crushed  slag  with  }ime  and  completing 
the  mixture  and  reduction  in  continuously  operated  tube  mills.  What- 
ever system  of  reduction  is  employed,  it  is  necessary  that  the  slag  be 
dried  as  completely  as  possible,  and,  with  modern  dryers,  the  amount 
of  moisture  in  the  dried  slag  can  be  economically  kept  well  below  1  per 
cent. 

In  this  connection  it  may  be  of  service  to  note  the  results  attained 
in  the  grinding  of  basic  Bessemer  slag  (for  use  as  a  fertilizer)  by  the 
Pottstown  Iron  Company.  A  2000-mm.  Jensch  ball  mill  was  there 
employed.  This  mill  consumed  about  13  H.P.  Its  normal  output 
was  20,000  Ibs.  in  ten  hours,  though  a  maximum  of  29,000  Ibs.  in  ten 
hours  had  been  reached  on  perfectly  dry  slag.  The  fineness  of  the 
product  was  such  that  95  to  98  per  cent  would  pass  a  100-mesh  sieve 
and  70  to  75  per  cent  a  150-mesh  sieve.  A  West  tube  mill  in  use  at 
an  American  slag-cement  plant  grinds  8|  barrels  per  hour  of  mix  to 
a  fineness  of  95  per  cent  through  200-mesh,  or  10  barrels  per  hour  to 
a  fineness  of  90  per  cent.  In  doing  this  it  uses  67  H.P.,  equivalent  to 
power  consumption  of  8  H.P.  hours  or  6.7  H.P.  hours,  respectively. 

Regulation  of  set. — Slag  cements  will  normally  set  very  slowly 
compared  to  Portland  cements.  As  this  interferes  with  their  use  for 
certain  purposes,  many  attempts  have  been  made  by  various  treat- 
ments to  reduce  their  set  ting- time.  There  is,  unfortunately,  another 
reason  why  the  manufacturer  should  desire  to  hasten  the  set  of  his 
product.  Most  of  the  slag  cements  sold  in  this  country  masquerade 
as  Portland,  and  it  is  desirable  to  the  manufacturer,  therefore,  to  make 
such  of  their  properties  as  are  brought  out  in  ordinary  tests  or  analyses 
approximate  to  those  of  true  Portland  cement.  The  set  of  slag  cements 
can  be  hastened  by  the  addition  of  puzzolanic  materials.  Of  these, 
burned  clay,  certain  active  forms  of  silica,  and  slags  high  in  alumina 
are  the  cheapest  and  most  generally  obtainable.  The  most  important 
method  of  regulation  is,  in  this  country  at  least,  the  Whiting  process, 
which  is  followed  at  two  large  American  plants. 

United  States  Patent  No.  544,706,  issued  in  1895  to  Jasper  Whiting, 


SLAG  CEMENT:  LIME,  MIXING  AND  GRINDING.  659 

covers  the  use  of  "caustic  soda,  potash,  sodium  chloride,  or  equiva- 
lents or  any  substance  of  which  the  latter  are  ingredients",  added  either 
as  aqueous  solutions  or  in  a  dry  state  at  any  stage  of  the  process  of 
slag-cement  manufacture.  In  the  specifications  accompanying  the 
application  for  this  patent,  the  patentee  states  that,  in  the  case  of  dry 
caustic  soda  the  amount  added  will  vary  from  0.125  to  3  per  cent, 
" depending  chiefly  upon  the  use  for  which  the  cement  is  intended". 
The  patent  was  subsequently  conveyed  to  the  Illinois  Steel  Company, 
and  the  process  covered  by  it  is  used  by  that  company  in  the  manu- 
facture of  its  "Steel  Portland  "  cement.  A  license  has  been  issued  to  the 
Brier  Hill  Iron  and  Coal  Company,  of  Youngstown,  Ohio,  under  which 
license  this  company  manufactures  its  "Brier  Hill  Portland  "  cement. 

The  process,  as  practised  in  the  slag-cement  plant  of  the  Illinois 
Steel  Company,  Chicago,  111.,  is  described  as  follows:  The  quicklime 
used  is  obtained  from  the  calcination  of  Marblehead  or  Bedford  lime- 
stone and  carries  less  than  1  per  cent  MgO.  On  its  arrival  at  the  mill 
it  is  unloaded  into  bins,  beneath  which  are  placed  two  screens  of  differ- 
ent mesh,  the  coarser  at  the  top.  A  quantity  of  lime  is  drawn  upon 
the  upper  screen,  where  it  is  slaked  by  means  of  the  addition  of  water 
containing  a  small  percentage  of  caustic  soda.  As  the  lime  is  slaked 
it  falls  through  the  coarse  screen  onto  the  finest  screen,  through  which 
it  falls  into  a  conveyor  which  carries  it  to  a  rotary  drier.  After  heat- 
ing, the  resulting  slaked  and  dried  lime  is  carried  by  elevators  to  hoppers 
above  the  tube  mills,  where  it  is  mixed  in  proper  proportions  with  the 
granulated  slag,  which  has  been  dried  and  powdered. 

General  Practice. — The  general  practice  followed  at  a  number  of 
American  and  European  slag-cement  plants  will  now  be  described. 

A  very  recent  and  typical  installation  is  shown  in  Fig.  163,  which 
gives  the  plan  and  elevation  of  the  slag-cement  plant  of  the  Stewart 
Iron  Co.,  at  Sharon,  Pa.  It  will  be  seen  that  the  granulated  slag  is 
passed  through  Ruggles-Coles  driers,  three  of  which  are  in  use,  and 
is  then  elevated  to  a  dry-slag  bin  on  the  second  floor  of  the  mill.  The 
lime  is  slaked  in  an  adjoining  room,  and  is  also  elevated  to  the  second 
floor.  Here  the  two  materials  are  fed  in  proper  proportions  to  a  screw 
conveyor,  which  carries  them  to  a  Broughton  mixer.  The  mix  is  then 
conveyed  to  three  West  tube  mills,  which  deliver  the  finished  product. 
The  Maryland  Cement  Company,*  at  Sparrows  Point,  Md.,  obtains  the 
slag  from  the  furnaces  of  the  Maryland  Steel  Company.  The  slag  is 
dried  in  Ruggles-Coles  driers,  and  after  mixing  with  the  slaked  lime 

*  Lewis,  F.  H.     Cement  Industry,  p.  184. 


CEMENTS.  LIMES,  AND  PLASTERS. 


is  ground  in  discontinuous  West  pebble  mills.  Mahon's  experiments 
preliminary  to  the  establishment  of  this  plant  are  discussed  on  an  earlier 
page. 

The  slag-cement  plant  of  the  Illinois  Steel  Company,  Chicago,  III., 
obtains  its  slag  from  the  blast-furnaces  of  that  company.     The  speci- 


FIG.  163. — Elevation  and  plan  of  Stewart  slag-cement  plant.     (The  Iron  Age.) 

fications  under  which  this  slag  is  received,  with  analyses  showing  its 
actual  range  in  composition,  will  be  found  on  a  previous  page.  After 
granulation  and  drying  in  a  specially  designed  dryer  the  slag  receives 
its  preliminary  reduction  in  Griffin  mills.  Meanwhile  the  lime  has  been 
slaked  as  described  in  detail  on  a  previous  page  (p.  659),  caustic  soda 
being  added  to  regulate  the  set  of  the  product.  The  ground  slag  and 


SLAG  CEMENT:  LIME,  MIXING  AND  GRINDING.  661 

this  prepared  lime  are  then  mixed,  and  the  mixture  receives  its  final 
reduction  in  Davidsen  tube  mills. 

At  the  plant  of  the  Birmingham  Cement  Company,*  at  Ensley,  Ala., 
slag  is  obtained  from  the  furnaces  of  the  Tennessee  Coal  and  Iron  Com- 
pany, located  in  near-by  towns.  The  slag  is  granulated  at  the  fur- 
naces. Oh  arrival  at  the  mills,  carrying  about  40  per  cent  of  water, 
it  is  dried  in  Ruggles-Goles  driers.  Two  of  these,  of  the  A2  style, 
are  in  operation.  After  drying,  the  slag  and  slaked  lime  are  fed  together 
to  West  ball  mills,  four  of  which  are  in  use,  and  the  mixture  is  finally 
reduced  in  West  tube  mills. 

The  Southern  Cement  Company,  at  North  Birmingham,  Ala.,  dries 
its  slag  in  a  style  A2  Ruggles-Coles  drier..  The  dried  slag  is  crushed 
in  a  Kent  mill.  After  mixing  with  the  slaked  lime,  the  final  reduction 
takes  place  in  West  tube  mills.  Two  brands  of  slag  cement  are  mar- 
keted. One,  a  normal  slag  cement,  is  said  to  average  about  CaO  55  per 
cent,  Fe203,  A1203,  12  per  cent,  Si02,  27  per  cent.  The  other  brand 
is  quicker  setting  and  is  said  to  carry  about  10  per  cent  less  CaO  and 
about  10  per  cent  more  SiO2. 

At  Skinningrove,  England,  slags  were  used  of  a  composition  varying 
between  the  following  limits:  Si02,  30  to  32  per  cent;  CaO,  30  to  33  per 
cent;  A12O3,  Fe2O3,  25  to  28  per  cent.  The  slag  on  issuing  from  the 
furnace  was  run  into  w  ter;  ground,  before  drying,  under  edge  runners, 
and  dried  on  iron  plates  in  a  drying  chamber.  The  dried  material  was 
ground  under  millstones;  sieved,  and  mixed  with  lime  (which  had 
been  slaked  and  screened)  in  the  proportions  usually  of  lime  33  Ibs.,  slag 
100  Ibs.  The  resulting  cement  varied  in  composition  between  the  follow- 
ing limits:  Si02,  24  to  26  per  cent;  CaO,  45  to  47  per  cent;  A1203, 
Fe2O3,  20  to  22  per  cent. 

At  Vitry,  France,  the  slag  is  struck  by  a  jet  of  water  immediately 
upon  issuing  from  the  furnace  and  carried  by  it  into  a  masonry  storage 
tank.  From  this  tank  the  granulated  slag  is  elevated  and  carried  to 
the  mill.  Five  driers  of  the  style  shown  in  Fig.  162  are  employed,  the 
dimensions  being  slightly  different  from  those  used  at  Choindez.  After 
drying  the  slag  is  sieved,  to  remove  the  coarser  particles,  passed  through 
six  mills  of  different  types,  and  again  sieved.  After  having  been  thus 
reduced  to  the  proper  fineness,  it  is  mixed  with  the  slaked  lime  in  ball 
mills  operated  discontinuously ;  the  proportions  being  about  40  Ibs. 
of  lime  to  100  Ibs.  of  slag. 


*  Eckel,  E.  C.     Engineering  News,  Jan.  23,  1902. 


662  CEMENTS,   LIMES,  AND  *  PLASTERS. 

The  slag-cement  plant  at  Konigshof,*  Germany,  utilizes  slag  from 
the  Carl-Emil  furnaces.  A  typical  analysis  of  this  slag  shows : 

Per  Cent. 

SiO2 26 . 29 

A1203 18.71 

FeO .v 1 . 80 

CaO '.:' f. 49.16 

MgO e 2.45 

The  more  important  constituents  commonly  +  vary  between  the 
following  limits: 

Per  Cent. 

SiO2 24  to  27 

A12O3 17  "  19 

CaO. 49  ' '  54 

Tht  slag  is  granulated,  dried,  and  ground  to  such  fineness  that  all 
passes  a  sieve  with  900  meshes  per  square  centimeter,  and  85  per  cent 
passes  a  sieve  of  5000  meshes  per  square  centimeter. 

The  limestone  is  obtained  from  quarries  at  Koneprus,  and  is  burned 
in  continuous  shaft  kilns.  Analysis  of  the  resulting  lime  shows: 

Per  Cent. 

SiO2 12 . 421 

A12O3 2 . 620 

Fe2O3 0.883 

CaO 81 .546 

MgO 1 . 751 

CO2 0 . 194 

Moisture 0 . 425 

From  this  analysis  it  would  seem  probable  that  the  lime  is  itself 
somewhat  hydraulic.  It  is  carefully  slaked,  and  stored  until  the  slaking 
is  complete,  after  which  it  is  screened  to  remove  the  coarser  particles. 

The  slag  and  lime  are  then  mixed  and  ground  together  in  propor- 
tions giving  a  cement  of  the  following  typical  composition: 

Per  Cent. 

SiO2 20 . 81 

A12O3 10.50 

Fe203 1.90 

CaO 55.90 

MgO 1.41 

S 0.58 

S03 0.91 

Loss  on  ignition      3 . 50 

*  Jour.  Iron  and  Steel  Inst.,  vol.  2,  1900,  p.  508. 


SLAG  CEMENT:  LIME,  MIXING  AND  GRINDING.  663 

The  specific  gravity  of  this  cement  ranges  between  2.80  arid  2.90. 
In  all  its  properties  it  resembles  other  slag  cements. 

Slag  cement  is  made  at  the  Cockerill  plant  *  at  Seraing,  Belgium, 
from  blast-furnace  slags  ranging  within  the  following  limits: 

Per  Cent. 

SiO2 27  to  32 

A12O3 12  "  22 

CaO 49  "  55 

The  slag  is  granulated  and  dried,  the  latter  taking  place  at  a  tem- 
perature of  about  500°  C.,  and  requiring  a  fuel  (coke)  consumption  of 
about  9  per  cent  of  the  weight  of  slag  dried.  The  slag  is  ground  so  as 
to  all  pass  a  sieve  of  76  meshes  to  the  inch,  and  leave  a  residue  of  only 
8  to  12  per  cent  on  a  sieve  of  180  meshes  to  the  inch.  Grinding  to  this 
fineness  requires  25  to  30  H.P.  for  the  production  of  450  to  800  kilo- 
grams per  hour  of  powdered  slag.  Lime  is  burned,  slaked  by  immer- 
sion, and  stored  eight  to  ten  days,  at  the  end  of  which  time  it  is  screened 
to  pass  a  76-mesh  sieve.  It  is  then  mixed  with  the  slag  in  the  propor- 
tion of  15  to  20  parts  of  lime  to  100  parts  slag. 

Costs  of  manufacture. — Data  regarding  the  cost  of  manufacture 
of  slag  cement  have  been  recently  published.!  The  figures  quoted  are 
said  to  have  been  the  costs  of  actual  manufacture  some  years  ago  at 
the  plant  of  the  Maryland  Cement  Company.  They  are  as  follows, 
being  based  on  a  production  of  5000  barrels  per  month: 

Per  Barrel. 

Mill  force,  labor  and  superintendence/ $0 . 160 

125  tons  of  coal  at  $3.05  per  ton 0 .076 

3000  bushels  of  lime  at  $0.16  per  bushel 0 . 100 

900  tons  of  slag  at  $0.50  per  ton 0 .090 

Repairs,  $100  per  month 0 .020 

Oil  and  grease,  $40  per  month 0 .007 

Contingencies 0.011 


Cost  of  administration.  .  .   $0 . 121 


$0.585 

These  figures  seems  rather  high  in  some  respects.  For  American, 
plants  I  should  say  that  the  average  cost  of  manufacture  should  not 
be  over  35  cents  per  barrel. 

*  Eng.  and  Min.  Jour.,  vol.  64,  pp.  515-516. 

f  Boilleau  and  Lyon.     Cost  of  making  slag  cement.     Municipal  Engineering, 
vol.  26,  p.  321.     May  1904. 


£64 


CEMENTS,  LIMES,  AND   PLASTERS. 


This  would  be  itemized  about  as  follows: 

TABLE  247. 
COSTS  OF  SLAG-CEMENT  MANUFACTURE  PER  BARREL. 

Min.  Max. 

Slag 04  .10 

Lime >'..... .^ 07  .12 

Coal • 03  .08 

Oil,  grease,  waste,  etc 005  .01 

Repairs 01  .03 

Labor U)5  .08 

Superintendence,  testing,  etc 03  .05 

.23|  .47 

Several  American  plants  have  to  my  knowledge  worked  quite 
<jlose  to  the  minimum  estimate  above  given.  To  this  cost  should  be 
added,  of  course,  interest  on  the  cost  of  the  plant.  If  the  plant  is  run- 
ning steadily  this  item  should  not  amount  to  more  than  two  or  three 
cents  a  barrel. 

Production  of  slag  cement. — The  following  data  on  the  slag  cement 
output  of  the  United  States  are  taken  from  the  volumes  on  mineral 
resources  annually  issued  by  the  U.  S.  Geological  Survey: 

TABLE  248. 
SLAG-CEMENT  PRODUCTION  IN  THE  UNITED  STATES, ^1899-1904. 


Year. 

Number 
of  Plants. 

Barrels. 

Value. 

1899  
1900 

3 

•   5 

233,000 
365,611 

? 

$274  208 

1901 

5 

272,689 

198  151 

1902  
1903  
1904  

6 

7 
8 

478,555 
525,896 
305,045 

425,672 
542,502 
226,651 

List  of  references  on  the  manufacture  of  slag  cement. 
Birk,  A.     Konigshofer  slag  cement.     Zeits.  angew.  Chemie.,  1900,  p.  1060-1061. 

Abstracts  in  Jour.  Soc.  Chem.  Industry,  vol.  19,  pp.  1114-1115.     1900. 

Jour.  Iron  and  Steel  Institute,  No.  2,  1900,  p.  508. 

Bodmer,  J.  J.     Mode    of   subdividing   and   special   use    of   subdivided   blast- 
furnace slag.     Trans    Amer.  Inst.  Min.  Engrs.  vol.  2,  pp.  81-83. 
Bodmer,  J.  J.     Blast-furnace   slag  cement.     Trans.  Amer.   Inst.  Min.  Engr., 

vol.  2,  pp.  83-84. 
Boilleau  and  Lyon      Cost   of   making   slag   cement.     Municipal   Engineering, 

vol.  26,  p.  321.     1904. 
.Bonnami,  H.     Frabrication  et  controle  des  chaux  hydrauliques  et  des  ciments. 

8vo,  276  pp.     Paris,  1888. 


SLAG  CEMENT:  LIME,  MIXING  AND  GRINDING.  665 

Detienne,  H.     Manufacture    and    properties    of    blast-furnace    slag    cement. 

Revue  universelle  des  mines,  Sept.,  1897. 

Eckel,  E.  C.     The  slag-cement  industry  in  the  United  States.     Mineral  Indus- 
try, vol.  10,  pp.  84-95.     1902. 
Eckel,  E.  C.     Slag-csment  and  slag-brick  manufacture  during  1902.     Mineral 

Industry,  vol.  11,  pp.  85-87.     1903. 
Elbers,  A.  D.     Notes    on   the    manufacture    and    properties    of   blast-furnace 

slag  cement.     Eng.  and  Mining  Journal,  vol.  64,  pp.  515-516.     1897. 
Hatt,  W.  K.     American  slag  cements.     Engineering  News,  Mch.  7,  1901. 
Jantzen.     Utilization  of  blast-furnace  sb'g.     Stahl  und  Eisen,  vol.  23,  pp.  361- 

375.     Abstract  in  Journal  Iron  and  Steel  Institute,  No.  1, 1903,  pp.  634- 

637. 
Lewis,  F.  H.     The  plant  of  the  Maryland  Cement  Co.,  Sparrows  Point,  Md. 

Engineering  Record,   July  15,  1899.      Cement  Industry,  pp.  184-187. 

1900. 
Lunge,  G.     Composition  of  granulated  slags.     Zeits.   angew.   Chemie,    1900, 

pp.  409-412.     Abstract  in  Journ.  Iron  and  Steel  Institute,  No.  1,  1901, 

p.  441. 
Mahon,  R.  W.     Slag-cement  experiments.    Journal  Franklin  Institute,  vol.  137. 

pp.  184-190. 
May,  E.     Slag  cement;  its  production  and  properties.     Stahl  und  Eisen,  Mch. 

and  April,  1898.     Iron  Age,  Sept.  1,  1898. 
Prost,  M.  A.     Note  sur  la  fabrication  et  les  proprietes  des  ciments  de  laitier 

Annales  des  Mines,  8th  series,  vol.  16,  pp.  158-208.     1889. 
Hedgrave,  G.  R.     Manufacture  and  properties  of  slag  cement.     Proc.  Insti- 
tution Civil  Engineers,  vol.  105,  pp.  215-230.     1891. 
Stead,  J.  E.     Hydraulic  cement  from  Cleveland  slag.     Cleveland  Institution 

of  Engineers,  1887. 
Von  Schwarz,  C.     Portland    cement    manufactured    from    blast-furnace    slag. 

Journal  Iron  and  Steel  Institute,  No.  1,  1903,  pp.  203-220. 
Anon.     Handling  blast-furnace  slag.     Iron  Age,  pp.  5-7.     Oct.  23,  1902. 
Anon.     Quick-setting  cement  from  blast-furnace  slag.     Thonindustrie  Zeitung, 

vol.  24  pp.  917-918.     Abstract  in  Journal,  Soc.  Chem.  Industry,  vol.  19, 

p.  903.     1900. 
Anon.     Cement  from  blast-furnace  slag  [at  Chicago,  111.]    Railway  Review, 

July  4,  1896. 
Anon.     The  manufacture  of  cement  from  slag  [at  Sharon,  Pa.]     Iron  Age,  pp.  15, 

16.     July  17,  1902. 

Anon.     Slag  cement  [at  Vitry,  France.]     Moniteur  Industrielle,  Feb.  13,  1897. 
Anon.     Slag  cement   [at  Konigshofer,  Germany.]     , Stahl  und  Eisen,  Sept.  1* 

1900. 

Anon.     Slag  cement  in  Germany.     U.  S.  Consular  Reports,  Feb.,  1896. 
Anon.     Manufacture  of  slag  cement  in  France.     Eng.  News,  Jan.  1,  1897. 


.-CHAPTER  XLIV. 

*  .          v* 

SLAG  CEMENTS:    COMPOSITION  AND  PROPERTIES. 

WHILE  slag  cements  are  sufficiently  like  Portland  cements  to  be 
usually  marketed  as  Portland,  certain  interesting  differences  between 
the  two  cements  are  shown  on  close  examination. 

Identification  of  slag  cement. — Slag  cements  may  usually  be  dis- 
tinguished from  Portland  cements  by  their  lighter  color,  inferior  specific 
gravity,  and  slower  set.  They  show  on  analysis  lower  lime  and  higher 
alumina  percentages  than  Portlands  and  usually  contain  an  appreciable 
amount  of  calcium  sulphide.  Owing  to  the  presence  of  this  last  named 
constituent  a  briquette  of  slag  cement  left  for  some  days  in  water  will 
show  upon  fracture  a  decided  greenish  tint;  if  it  has  been  exposed  to 
salt  water,  this  tint  will  be  much  more  marked,  and  the  odor  of  hydrogen 
sulphide  will  be  observed.  Two  things  should  be  noted,  however,  in 
this  connection.  The  presence  of  sulphides  though  usual  is  not  a  neces- 
sary occurrence  in  slag  cements;  and,  on  the  other  hand,  sulphides  are 
occasionally  present  in  Portland  cements,  being  formed  from  the  sul- 
phates in  case  the  flame  of  the  kiln  is  not  sufficiently  oxidizing.  Another 
chemical  difference  between  the  two  types  of  cement  is  in  the  high  "loss 
on  ignition  "  shown  by  slag  cements.  This  loss,  which  may  range  from 
4  to  8  per  cent,  is  due  largely  to  the  water  carried  by  the  slaked  lime. 

Chemical  Composition  of  Slag  Cements. 

The  ultimate  composition  of  a  sample  of  slag  cement  will,  of  course, 
be  brought  out  by  chemical  analysis:  but  the  fact  that  the  material 
is  not  a  chemical  compound  but  merely  a  mechanical  mixture  will  not 
be  shown  in  the  ordinary  report  of  such  an  analysis.  The  average 
commercial  chemist  will,  moreover, — particularly,  if  he  be  accustomed 
to  analyzing  Portland  cements — make  careless  and  erroneous  state- 
ments concerning  three  important  points.  The  three  points  noted  are: 
(a)  the  condition  of  the  iron  which  is  present,  (6)  the  condition  of  the 
sulphur  which  is  present,  and  (c)  the  nature  of  the  "loss  on  ignition". 

A  discussion  of  analytical  methods  will  not  be  undertaken,  as  that, 
subject  does  not  properly  belong  in  a  treatise  of  this  character.  But 

666 


SLAG  CEMENTS:  COMPOSITION  AND   PROPERTIES. 


667 


it  may  be  of  value,  not  only  to  engineers  and  slag-cement  manufacturers, 
but  to  commercial  chemists,  to  state  in  some  detail  what  substances 
are  to  be  expected  in  examining  a  normal  slag  cement.  Slag  cement, 
when  ready  for  sale,  is  a  mechanical  mixture  of  slaked  lime  and  slag. 
The  slaked  lime  is  lime  hydrate  [Ca2(OH)2];  the  slag  may  be  regarded 
as  a  calcium  aluminum  silicate  (x.CaO,  T/.A^Os.SiC^).  In  addition 
to  the  essential  ingredients — lime,  silica,  alumina,  and  water — con- 
tained in  these  two  components  of  the  cement,  certain  other  constitu- 
ents may  occur  in  small  but  often  interesting  percentages.  Of  these 
sulphur,  iron,  magnesia,  carbon  dioxide,  fluorine  and  soda  are  those 
most  commonly  found. 

Analyses  of  a  number  of  American  slag  cements  are  presented  in 
the  following  table.  The  Cementation  Index  of  several  of  these  has 
been  calculated,  and  it  will  be  seen  that  it  gives  values  (1.59,  1.67,  1.72, 
1.87)  far  above  those  given  by  any  modern  Portland  cement: 

TABLE  249. 

ANALYSES  OF  AMERICAN  SLAG  CEMENTS. 


1. 

2. 

3. 

4. 

5. 

6. 

Silica  (SiO2)          

27  78 

27  20 

28  40 

28  95 

29  80 

27  80 

Alumina  (A12O3)     .... 

[11  40  1 

Iron  oxides  (FeO,Fe2O3) 
Lime  (CaO)  
Magnesia  (MgO)  

\  11.70 

51.71 
1.39 

14.18 

50.33 
3  22 

12.80 

51.50 
n  d 

1    0.54/ 
50.29 
2  96 

12.30 

51.14 
2  34 

11.10 

50.96 
2  2** 

Sulphur  (S)  

1.31 

0.15 

1  40 

1  37 

1  37 

1  18 

Carbon  dioxide  (CO2).  .  . 
Water 

}    n.  d. 

4.25 

n.  d. 

3.39 

2.60 

5.30 

Cementation  Index.  .  .  . 

1.67 





1.72 

7. 

8. 

9. 

10. 

11. 

12. 

Silica  (SiO2) 

27  15 

28  84 

30  98 

28  90 

2Q   AA 

on    on 

Alumina  (A12O3)  

10.80 

10  42 

11  72 

Iron  oxides  (FeO,Fe2Os). 
Lime  (CaO) 

0.90 
51  57 

n.  d. 
51  81 

n.  d. 
51  07 

j  12  .  72 
KI    IQ 

12.62 
KI     17 

11.26 

C1      Q-l 

Magnesia  (MgO)  
Sulphur  (S) 

2.70 
1  38 

2.21 
1  42 

1.45 
1  22 

L.87 
1    07 

1.98 
1   1  ^ 

3.37 

1    qrv 

Carbon  dioxide  (CO3)  
AVater  

)    3.50 

n.  d. 

n.  d. 

n.  d. 

n.  d. 

n.  d. 

Cementation  Index   .    . 

1  59 

1  87 

Birmingham  Cement  Co.,  Ensley,  Ala.     Private  communi- 


1.  "Southern  Cross  Portland' 

cation. 

2.  "Steel  Puzzolan".     Illinois  Steel  Co.,  Chicago,  111.     Lathury  &  Spackman,  anal.     Mfrs. 

circular. 
3-6.   "Steel  Puzzolan".     Illinois  Steel  Co.,  Chicago,  111. 

7.  Maryland  Cement  Co.,  Sparrows  Pt.,  Md.     Cement  Directory,  2d  ed.,  p.  207. 

9.  "Brier  Hill  Portland".    Brier  Hill  Coal  <fe  Iron  Co.,  Brier  Hill,  Ohio.     Private  communica- 
tion . 
10-12.  "Stewart  Portland".     Stewart  Portland  Cement  Co.,  Sharon,  Pa.     Private  communication. 


668 


CEMENTS,  LIMES,  AND   PLASTERS, 


Table  250  contains  the  analysis  of  a  number  of  European  slag  cements, 
as  given  by  various  authorities.  It  will  be  seen  that,  despite  the  appar- 
ently great  variations  in  practice,  the  ultimate  composition  of  the  finished 
cement  falls  within  quite  narrow  limits.  The  range  in  composition  of 
a  good  slag  cement  may  be  considered  to  be  about:  SiC>2,  22  to  30  per 
cent;  A12O3  +  Fe2O3,  11  to  16  per  c#nt;  CaO,  49  to  52  per  cent;  MgO, 
less  than  4  per  cent;  S,  less  than  1.5  per  cent;  ignition  loss,  2.5  to  7.5 
per  cent. 

TABLE  250. 
ANALYSES  OF  EUROPEAN  SLAG  CEMENTS. 


Components. 

Bruns- 
wick, 
Germany 

Choindez, 
Switzer- 
land. 

Bilbao, 
Spain. 

Donjeux. 

Saulnes, 
France. 

SiCX, 

25   56 

19  5 

30  56 

23  85 

24  85 

24  55 

22   45 

ALOo 

11  20 

17  5 

13  31 

13  95 

12  10 

14  05 

13  95 

FeO 

0  25 

1   10 

3  85 

1  85 

3  30 

CaO 

49  70 

54  0 

45  01 

51  40 

49  20 

49  25 

51   10 

MgO  . 

2  96 

1  95 

1  75 

1  60 

1.35 

S     .. 

*4  63 

1  30 

SO3  

fl  41 

0  45 

1  35 

0.60 

0.35 

Loss  on  ignition 



7.05 

5.65 

7.75 

7.50 

*CaS. 


t  CaSO4. 


Physical  Properties. 

Specific  gravity. — The  specific  gravity  of  slag  cements  usually  ranges 
from  2.7  to  2.9,  as  compared  with  the  3.15  which  may  be  considered 
a  fair  average  for  the  specific  gravity  of  a  good  Portland  cement.  The 
slag  cements  are,  therefore,  appreciably  lighter  than  Portlands,  and 
more  bulk  is  obtained  for  the  same  weight.  The  following  determi- 
nations of  the  specific  gravity  of  three  American  slag  cements  have 
been  made  at  Philadelphia: 

Toltec 2.861 

Climax. 2 . 888 

Penn 2.831 

Aside  from  its  use  as  a  method  of  distinguishing  slag  cements  from 
Portlands,  the  determination  of  the  specific  gravity  of  the  cement  is 
of  little  engineering  importance.  A  point  which  is  of  engineering  impor- 
tance, however,  appears  to  have  been  overlooked  by  experimenters.  Sa 
far  as  the  writer  knows,  the  relative  specific  gravities  of  set  briquettes, 
composed  of  neat-slag  cement  and  neat-Portland  cement  respectively, 
have  never  been  determined.  A  knowledge  of  the  two  values  would 
be  of  service,  at  times,  in  selecting  the  type  of  cement  to  be  used.  For 


SLAG  CEMENTS:  COMPOSITION  AND  PROPERTIES. 


some  purposes,  as  in  dams,  a  heavy  material  is  preferable;  for  others, 
as  in  floors,  the  lighter  cement  would  be  better. 

Color  of  slag  cements. — Slag  cements  can  usually  be  distinguished 
from  Portlands  by  being  much  lighter  in   color  and  slightly  different' 


140  210 

AGE  IN  DAYS 


860 


FIG.  164.* — Effect  on  tensile  strength  of  slag  cements  of  hardening  in  air  or  in* 

water.      (Tetmajer.) 


140  210 

AGE  IN  DAYS 


2SO 


350 


PIG.   165.* — Effect  on  compressive  strength  of  slag  cement  of  hardening  in  air  or  in 

water.     (Tetmajer.) 

in  tint,  while  from  most  natural  cements  they  differ  markedly  in  tint. 
They  are  commonly  bluish-white  to  lilac,  the  exact  color  of  any  speci- 
men depending  partly  on  the  respective  colors  of  the  lime  and  th& 
slag  which  have  been  used  in  its  manufacture,  but  more  largely  on. 

*  From  Johnson's  "  Materials  of  Construction  ",  p.  576. 


670  CEMENTS,  LIMES,  AXD   PLASTERS. 

the  relative  proportions  in  which  these  ingredients  have  been  mixed. 
Slag  cements  do  not  stain  masonry;  and  an  imported  cement  of  closely 
related  origin  (Meier's  Pozzuolan)  has  long  been  in  favor  in  this  country 
for  architectural  uses,  because  of  this  non-staining  property. 

Rapidity  of  set. — Normally  slag  cements  are  slower  setting  than 
Portlands.  Whether  this,  property  is  a  disadvantage  or  not  will  depend 
on  the  use  to  which  the  cement  is  -to  be  applied.  As  before  mentioned 
the  rapidity  of  set  increases  naturally  with  the  amount  of  alumina  in 
the  slag.  Set  can  be  artificially  hastened  by  the  addition  of  puzzo- 
lanic  material  to  the  cement;  burned  clay,  active  forms  of  silica,  slags 
high  in  alumina,  etc.,  are  additions  which  are  both  effective  and  cheap. 
The  treatment  of  the  cement  during  manufacture  with  alkalies  to  accel- 
erate the  set  has  already  been  discussed. 

Strength. — While  slag  cements  fall  below  high-grade  Portlands  in 
tensile  strength,  good  American  slag  cements  develop  sufficient  strength 
to  pass  the  usual  specifications  for  Portlands.  Tested  neat  they  do 
not  approximate  so  closely  to  the  Portlands  as  they  do  if  tested  in  2 :1 
or  3:1  mortars.  Part  of  this  property  may  be  due  to  the  fact  that  they 
are  in  general  ground  finer  than  Portlands,  especially  than  foreign 
Portlands.  Prof.  W.  K.  Hatt  recently  made  a  large  series  of  tests  on 
American  slag  cements,  and  reported  that  there  was  no  noticeable 
deficiency  in  strength  of  briquettes  kept  in  air  as  compared  with  those 
kept  in  water.  Other  investigators  have  arrived  at  opposite  conclu- 
sions; and  it  is  probable  that  these  conflicting  results  arise  from  differ- 
ences in  the  chemical  composition  of  the  various  brands  tested. 

Resistance  to  mechanical  wear. — Slag  cements  are  notably  deficient 
in  this  property,  and  are  therefore  not  available  for  use  for  the  surface 
of  pavement,  floors,  etc.,  where  this  quality  must  be  highly  developed; 
they  seem  to  be  well  fitted,  however,  for  pavement  foundations,  or 
.indeed  for  any  wrork  which  will  not  be  exposed  to  dry  air,  and  in  which 
a  high  strength  is  not  necessary. 

Ratio  of  tensile  to  compressive  strength. — This  ratio,  which  is  of 
importance  (as  noted  in  the  discussion  of  Portland  cements)  seems  to 
be  much  lower  for  slag  cements  than  for  Portlands.  In  the  case  tabu- 
lated below,  the  results  of  tests  show  the  ratio  for  slag  cement  to  aver- 
age 5.3:1,  in  place  of  the  10:1  ratio,  which  is  a  fair  average  for  Port- 
land cements. 

™,  ,.      compressive    strength  , 

The  average  value  for  ~ — -, for  the  whole  series 

tensile  strength 

is  5.3. 


SLAG   CEMENTS:  COMPOS ITIOX  AND  PROPERTIES. 


671 


TABLE  251. 
TENSILE  vs.  COMPRESSIVE  STRENGTH  OF  SLAG  CEMENTS. 


Mixture. 

Test. 

7  Days. 

28  Days. 

7  Days. 

28  Days. 

7  Days. 

1  Month. 

Neat  cement  

Tension 

441 

528 

480 

503 

«          « 

Compression 
tf-i-T 

2054.5 
4.66 

2470 
5.15 

2830 
5.63 

1  cement,  3  sand.  . 

Tension 

170 

219 

145 

200 

171 

243 

<.              a 

Compression 

486.5 

933 

938 

1138 

1529 

0.+  T 

2.86 

6.44 

4.69 

6.65 

6.29 

List  of  references  on  properties  and  testing  of  slag  cements. — 

In  addition  to  the  list  given  below,  many  of  the  papers  cited  on  pages 
664-665  will  be  found  to  contain  data  on  the  properties  and  testing  of 
slag  cements. 

Bonnami,  H.     Fabrication  et  controle  des  chaux  hydrauliques  et  des  ciments. 

8vo,  276  pp.     Paris,  1888. 

Candlot,  C.     Ciments  et  chaux  hydrauliques.     8vo.     Paris,  1889. 
Datienne,  H.     Manufacture   and  properties  of  slag  cement.     Revue  univer- 

selle  des  mines,  Sept.,  1897. 
Elbers,  A.  D.     Notes  on  the  manufacture  and  properties  of  blast-furnace  slag 

cement.     Eng.  and  Mining  Journal,  vol.  64,  pp.  515-516.     1897. 
Hatt,  W.  K.'    American  slag  cements.     21st  Ann.  Rep.  Proceedings  Indiana 

Engineering  Soc.,  pp.  45-65.     1901.     Also  in  Engineering  News,  March  7, 

1901. 
Le  Chatelier,  H.     Tests  of  hydraulic  materials.     Trans.  Am.  Inst.  Min.  Eng., 

vol.  22,  pp.  3-52.     1894. 
Mahon,  R.  W.     Slag-cement  experiments.     Journal  Franklin  Institute,  vol.  137, 

pp.  184-190.     1894. 
May,  E.     Slag   cement :    its    production   and   properties.     Stahl    und   Eisen, 

March  and  April,  1898.     Abstract  in  Iron  Age,  Sept.  1,  1898. 
Prost,  M.  A.     Note  sur  la  fabrication  et  les  proprietes  des  ciments  de  laitier. 

Annales  des  .Mines,  8th  series,  vol.  16,  pp.  158-208.     1889. 
Redgrave,  G.  R.  v  Manufacture  and  properties  of  slag  cement.     Proc.  Institu- 
tion Civil  Engineers,  vol.  105,  pp.  215-230.     1891. 
Rohland,  P.     Influence   of   catalysers   on   velocity  of  hydration  of   cements. 

plasters,  and  limes.     Zeitschrift  anorg.  Chemie,  vol.  31,  pp.  437-444. 

Abstract  in  Journal  Soc.  Chem.  Industry,  vol.  21,  p.  1233.     1901. 
U.  S.  Army  Board  of  Engineers.      Report  on  Steel  Portland  Cement.      Svo, 

112  pp.     Washington,  1900. 
Whiting,  J.     The  definition  of  Portland  cement.     Engineering  Record,  July  30, 

1898. 
Anon.     The    distinction   between   slag   and   Portland   cements.     Engineering 

Record,  July  9,  1898. 


672  CEMENTS,  LIMES,  AND   PLASTERS. 

Specifications  for  slag  cement. — So  far  as  known,  the  only  American 
specifications  for  slag  cement  are  those  prepared*  and  published  in 
1902  by  the  Engineer  Corps,  U.  S.  Army.  These  are  reprinted  below. 


SPECIFICATIONS  FOR  P.UZZOLAN  CEMENT. 

1     .  v* 

Engineer  Corps,  U.  S.  A.,  1902. 

(1)  The  cement  shall  be  a  Puzzolan  of  uniform^  quality,  finely  and 
freshly  ground,  dry,  and  free  from  lumps,  made  by  grinding  together 
without    subsequent    calcination    granulated    blast-furnace    slag    with 
slaked  lime. 

(2)  The  cement  shall  be  put  up  in  strong  sound  barrels  well  lined 
with  paper,  so  as  to  be  reasonably  protected  against  moisture,  or  in 
stout  cloth  or  canvas  sacks.     Each  package  shall  be  plainly  labeled 
with  the  name  of  the  brand  and  of  the  manufacturer.     Any  package 
broken  or  containing  damaged  cement  may  be  rejected,  or  accepted 
as  a  fractional  package,  at  the  option  of  the  United  States  agent  in 
local  charge. 

(3)  Bidders  will  state  the  brand  of  cement  which  they  propose  to 
furnish.     The  right  is  reserved  to  reject  a  tender  for  any  brand  which 
has  not  given  satisfaction  in  use  under  climatic  or  other  conditions  of 
exposure  of  at  least  equal  severity  to  those  of  the  work  proposed,  and 
for  any  brand  from  cement  works  that  do  not  make  and  test  the  slag 
used  in  the  cement. 

(4)  Tenders   will   be    received    only   from   manufacturers    or   their 
authorized  agents. 

(The  following  paragraph  will  be  substituted  for  paragraphs  3  and 
4  above  when  cement  is  to  be  furnished  and  placed  by  the  contractor: 

No  cement  will  be  allowed  to  be  used  except  established  brands 
of  high-grade  Puzzolan  cement  which  have  been  in  successful  use  under 
similar  climatic  conditions  to  those  of  the  proposed  work  and  which 
come  from  cement  works  that  make  the  slag  used  in  the  cement.) 

(5)  The  average  weight  per  barrel  shall  not  be  less  than  330  Ibs. 
not.     Four  sacks  shall  contain  1  barrel  of  cement.     If  the  weight  as 
determined  by  test  weighings  is  found  to  be  below  330  Ibs.  per  barrel, 
the  cement  may  be  rejected,  or,  at  the  option  of  the  engineer  officer 
in  charge,  the  contractor  may  be  required  to  supply,  free  of  cost  to 
the  United  States,  an  additional  amount  of  cement  equal  to  the  shortage. 

(6)  Tests  may  be  made  of  the  fineness,  specific  gravity,  soundness, 
time  of  setting,  and  tensile  strength  of  the  cement. 


DEPARTMENT  OF  CIVIL  ENGINEERING 
--., 

SLAG  CEMENTS:  COMPOSITION   AND  PROPERTIES.  673 

(7)  Fineness. — Ninety-seven    per    cent    of   the    cement    must    pass 
through  a  sieve  made  of  No.  40  wire,  Stubb's  gauge,  having  10,000 
openings  per  square  inch. 

(8)  Specific  gravity. — The  specific  gravity  of  the  cement,  as  deter- 
mined from  a  sample  which  has  been  carefully  dried,  shall  be  between 
2.7  and  2.8. 

(9)  Soundness. — To   test   the   soundness   of   cement,    pats   of   neat 
cement  mixed  for  five  minutes  with  18  per  cent  of  water  by  weight 
shall  be  made  on  glass,  each  pat  about  3  inches  in  diameter  and  \  inch 
thick  at  the  center,  tapering  thence  to  a  thin  edge.     The  pats  are  to  be 
kept  under  wet  cloths  until  finally  set,  when  they  are  to  be  placed  in 
fresh  water.     They  should  not  show  distortion  or  cracks  at  the  end 
of  twenty-eight  days. 

(10)  Time  of  setting. — The  cement  shall  not  acquire  its  initial  set 
in  less  than  forty-five  minutes  and  shall  acquire  its  final  set  in  ten  hours. 
The  pats  made  to  test  the  soundness  may  be  used  in  determining  the 
time  of  setting.     The  cement  is  considered  to  have  acquired  its  initial 
set  when  the  pat  will  bear,  without  being  appreciably  indented,  a  wire 
-^  inch  in  diameter  loaded  to  \  Ib.  weight.     The  final  set  has  been 
acquired  when  the  pat  will  bear,  without  being  appreciably  indented, 
a  wire  ^  inch  in  diameter  loaded  to  1  Ib.  weight. 

(11)  Tensile  strength. — Briquettes  made  of  neat  cement,  after  being 
kept  in  air  under  a  wet  cloth  for  twenty-four  hours  and  the  balance 
of  the  time  in  water,  shall  develop  tensile  strengths  per  square  inch  as 
follows : 

After  seven  days,  350  Ibs.;  after  twenty-eight  days,  500  Ibs. 
Briquettes  made  of  one  part  cement  and  three  parts  standard  sand 
by  weight  shall  develop  tensile  strength  per  square  inch  as  follows: 
After  seven  days,  140  Ibs.;    after  twenty-eight  days,  220  Ibs. 

(12)  The  highest  result  from  each  set  of  briquettes  made  at  any 
one  time  is  to  be  considered  the  governing  test.     Any  cement  not  show- 
ing an  increase  of  strength  in  the  twenty-eight-day  tests  over  the  seven- 
day  tests  will  be  rejected. 

(13)  When  making  briquettes  neat  cement  will  be  mixed  with  18 
per  cent  of  water  by  weight,  and  sand  and  cement  with  10  per  cent  of 
water  by  weight.     After  being  thoroughly  mixed  and  worked  for  five 
minutes  the  cement  or  mortar  will  be  placed  in  the  briquette  mould 
in  four  equal  layers  and  each  layer  rammed  and  compressed  by  thirty 
blows  of  a  soft  brass  or  copper  rammer,  f  of  an  inch  in  diameter  or 
T\  of  an  inch  square,  with  rounded  corners,  weighing  1  Ib.     It  is  to 
be  allowed  to  drop  on  the  mixture  from  a  height  of  about  half  an  inch. 


674  CEMENTS,  LIMES,  AND  PLASTERS. 

When  the  ramniing  has  been  completed  the  surplus  cement  shall  be 
struck  off  and  the  final  layer  smoothed  with  a  trowel  held  almost  hori- 
zontal and  drawn  back  with  sufficient  pressure  to  make  its  edge  follow 
the  surface  of  the  mould. 

(14)  The  above  are  to  be  considered  the  minimum  requirements. 
Unless  a  cement  has  been  recently  .used   on  a  work  under  this  office, 
bidders  will  deliver  a  sample  barrertor  test  before  the  opening  of  bids. 
If  this  sample  shows  higher  tests  than  those  given  above,  the  average 
of  tests  made  on  subsequent  shipments  must  come  up  to  those  found 
with  the  sample. 

(15)  A  cement  may  be  rejected  in  case  it  fails  to  meet  a,ny  of  the 
above  requirements.     An  agent  of  the  contractor  may  be  present  at 
the  making  of  the  tests,  or,  in  case  of  the  failure  of  any  of  them,  they 
may  be  repeated  in  his  presence.     If  the  contractor  so  desires  the  engi- 
neer officer  in  charge  may,  if  he  deems  it  to  the  interest  of  the  United 
States,  have  any  or  all  of  the  tests  made  or  repeated  at  some  recog- 
nized testing  laboratory  in  the  manner  herein  specified,  all  expenses  of 
such  tests  to  be  paid  by  the  contractor.     All  such  tests  shall  be  made 
on  samples  furnished  by  the  engineer  officer  from  cement  actually  delivered 
to  him. 


CHAPTER  XLV. 
SLAG  BRICKS  AND  SLAG  BLOCKS.* 

UNDER  the  names  of  "slag  brick  ",  "slag  tile  ",  "slag  block  ",  "scoria 
brick  ",  etc.,  two  very  different  products  have  been  included  by  various 
writers.  Both  products  are  made  from  blast-furnace  slag,  but  the  two 
classes  differ  so  greatly  in  their  methods  of  manufacture  and  properties 
that  it  seems  necessary  to  describe  them  separately.  This  has  accord- 
ingly been  done,  the  names  "slag  bricks  "  and  "slag  blocks  "  being 
supplied  to  the  respective  classes.  As  here  used,  the  term  "slag  brick  " 
will  be  confined  to  those  bricks,  tiles,  etc.,  which  are  made  by  mixing 
slaked  lime  with  ground  slag,  molding  the  mixture  by  hand  or  in  a 
brick-machine,  and  drying  or  steaming  the  product.  The  term  "slag 
blocks  ",  on  the  other  hand,  will  be  applied  to  the  products  made  by 
pouring  molten  slag  into  brick -shaped  molds. 

Slag  Bricks. 

The  structural  products  included  in  this  chapter  under  the  head 
of  "slag  bricks  "  include  those  which  are  made  by  mixing  granulated 
slag  with  slaked  lime  or  with  slag  cement,  molding  the  mixture  in  a 
brick-press  or  by  hand,  and  drying  it  in  the,  air,  with  or  without  the 
use  of  steam.  It  will  be  noted  that  all  the  raw  materials  used  in  this 
industry  are  the  same  as  those  utilized  in  the  manufacture  of  slag  cement; 
and  indeed  the  manufacture  of  slag  bricks  may  be  considered  as  being 
merely  a  specialized  phase  of  the  slag-cement  industry. 

Though  the  slag-cement  industry  of  the  United  States  is  in  a  fairly 
satisfactory  condition  no  serious  attempt  seems  to  have  been  made  to 
prepare  slag  bricks,  tile,  pipes,  etc.,  on  a  commercial  scale.  Small  amounts 
of  slag  bricks  have  been  made  for  use  about  the  mills  and  furnaces 

*  Over  half  of  the  material  contained  in  this  chapter  is  reprinted,  by  courtesy 
of  Engineering  News,  from  an  article  by  the  present  writer  published  in  its  issue 
of  April  30,  1903. 

675 


676  CEMENTS,  LIMES,  AND  PLASTERS. 

and  for  the  local  market,  but  apparently  no  attempt  has  been  made  to 
extend  the  manufacture. 

Methods  of  manufacture. — The  slags  used  are  basic  blast-furnace 
slags,  but  a  somewhat  greater  range  in  composition  is  allowable  for 
slag  bricks  than  when  the  slags  are  to  be  used  in  cement-manu- 
facture. The  analyses  quoted  in  the*  present  chapter  may  be  regarded  as 
fairly  representative  of  the  class  of  slags  used  in  slag-brick  manufac- 
ture. It  will  be  seen  that  the  silica  ranges  from  22.5  per  cent  to  35  per 
cent;  the  alumina  and  iron  oxide  together,  from  1^6.1  per  cent  to  21  per 
cent;  the  lime,  from  40  per  cent  to  51.5  per  cent.  As  in  slag  cements, 
sulphur  is  an  objectionable  constituent.  Much  of  it,  fortunately,  is 
removed  during  the  process  of  granulating  the  slag. 

The  general  steps  in  slag-brick  manufacture  may  be  stated  as  follows; 
Slags  of  proper  composition  are  granulated  by  being  run  into  a  stream 
of  cold  water  immediately  upon  issuing  from  the  furnace.  This  causes 
the  slag  to  break  up  into  little  porous  particles,  thereby  greatly  reducing 
the  expense  of  subsequent  grinding:  Granulation  also  confers  hydraulie 
properties  on  the  slag,  and  removes  part  or  all  of  its  contained  sulphur. 
The  granulated  slag  is  dried  and  pulverized.  Powdered  slaked  lime 
is  added  in  sufficient  uantity  to  bring  the  total  calcium  oxide  content 
of  the  mixture  up  to  about  55  per  cent.  This  mixing,  as  well  as  the 
previous  burning  and  slaking  of  the  lime,  must  be  carefully  and  thor- 
oughly done  in  order  to  prevent  subsequent  disintegration  of  the  bricks. 
Usually,  during  or  after  the  mixing,  a  small  amount  of  water  is  added. 
The  mixture  is  then  molded  into  shape,  either  by  hand  or  in  a  brick- 
machine.  After  shaping,  the  bricks  are  dried  in  the  open  air,  this  usu- 
ally taking  six  to  ten  days  in  dry  weather.  In  the  best  practice,  the 
bricks  are  retained  for  several  months,  after  drying,  in  order  that  they 
may  be  well  hardened  before  marketing. 

Though  over  90  per  cent  of  the  total  production  of  slag  brick  is  at 
plants  following  the  above  methods,  three  other  methods  may  be  briefly 
noted.  At  a  few  plants  the  granulated  slag  is  mixed,  without  drying, 
with  the  unslaked  lime;  the  slag  furnishing  sufficient  water  to  slake 
the  lime.  Slaking  in  this  way  is  very  imperfectly  done,  however,  and 
the  practice  should  never  be  followed  if  high-grade  bricks  are  expected. 
At  a  few  other  plants,  notably  at  the  Bilbao  plant  described  below, 
slag  is  mixed  with  slag  cement  instead  of  with  lime.  At  certain  English 
plants,  also  noted  below,  the  slag  bricks  are  hardened  in  steam  cylinders 
like  the  cylinders  used  in  lime-sand  brick  manufacture. 

Slag  bricks  vary  in  color  from  a  grayish  white  to  dark  gray.  They 
weigh  less  than  clay  bricks  of  equal  size,  are  said  to  require  less  mortar 


SLAG  BRICKS  AND  SLAG  BLOCKS.  677 

in  laying  up,  and  are  at  least  equal  to  clay  bricks  in  crushing  strength. 
The  product  usually  seems  to  find  a  ready  market,  though,  of  course, 
the  low  value  of  the  material,  relative  to  its  bulk  and  weight,  precludes 
long  railroad  transportation. 

Methods  at  special  plants. — Slag  bricks  were  manufactured  at  the 
Cleveland  Slag  Works,  Middlesborough,  England;  but  the  manufac- 
ture has  been  discontinued  for  some  years  At  this  plant  the  wet  granu- 
lated slag  was  mixed  with  "selenitic  lime"  (see  Ch.  XV)  instead  of 
with  common  lime.  The  selenitic  lime  was  composed  of  80  per  cent 
quicklime,  10  per  cent  gypsum,  and  10  per  cent  iron  oxide.  About 
670  Ibs.  of  this  selenitic  lime  was  sufficient  for  1000  bricks.  The  mix- 
ture of  slag  and  lime  was  pressed  to  shape  in  a  brick-press;  and  the 
bricks  were  stacked  in  sheds  for  a  week,  to  harden  enough  to  handle 
well.  After  this  they  were  stacked  in  the  open  air  for  five  or  six  weeks 
more,  when  they  were  ready  for  use.  The  bricks  were  dull-gray  in 
color,  and  very  hard  and  tough.  Buildings  onstructed  of  them  over 
twenty  years  ago  are  still  in  a  good  state  of  preservation.  The  manu- 
facture of  slag  bricks  at  these  works  was  given  up  for  reasons  not  con- 
nected with  the  technical  value  of  the  product,  which  seems  to  have 
acquired  an  excellent  local  reputation 

At  Vitry,  France,  the  manufacture  *  of  slag  bricks  and  pipes  is 
carried  on  in  connection  with  the  manufacture  of  slag  cement.  The 
bricks  are  made  by  mixing  60  parts  of  slaked  lime  with  from  250  to 
300  parts  of  granulated  slag.  Sufficient  water  is  added  to  this  mix- 
ture to  make  a  firm  paste,  from  which  the  bricks  are  molded  in  hand- 
or  steam-presses.  These^  slags  are  found  to  be  especially  useful  for 
foundations  or  basement  work,  pavements,  etc.  "Facing  brick  "  are 
made  from  a  similar  mixture,  with  the  addition  of  some  fine  sand. 
Sewer  pipes  are  made  from  a  mixture  consisting  of  500  kgs.  of 
slag  cement  and  1  cu.  m.  of  sand.  This  mixture  is  made  into  a 
stiff  mortar,  and  forced  into  steel  molds  by  iron  rammers.  The  molds 
are  removed  as  soon  as  the  ramming  has  finished.  The  pipes  are  then 
dried  for  three  days,  after  which  they  are  immersed  in  water  for  twenty- 
four  hours.  They  are  then  stacked  in  the  factory  ground  for  several 
months,  after  which  they  are  ready  for  market. 

Slag  bricks  are  manufactured  f  on  a  large  scale  at  Kralovedvoor, 
near  Prague,  Bohemia.  The  slags  normally  used  at  this  plant  vary  in 
composition  within  the  following  limits; 

*  Engineering  News,  Jan.  1,  1897. 

f  Engineering  and  Mining  Journal,  April  16,  1898. 


678  CEMENTS,  LIMES,  AND   PLASTERS. 

Per  Cent. 

Silica  (SiO2) 25.8  to  27.0 

Alumina  (A1,O3) 17.3  "  19.3 

Iron  oxide  ( FeO) 1.5"     1.7 

Manganese  oxide  (MnO) 0.0"     0.1 

Lime  (CaO) 51 . 4  "  51 . 5 

Magnesia  (MgO) y ^ 0.4"     25 

Sulphur  (S) ; 1.3"     1.8 

As  the  slag  issues  from  the  furnaces  it  is  run  into  an  inclined  iron 
trough  in  which  cold  water  is  flowing.  In  addition*. to  granulating  the 
slag,  a  considerable  portion  of  the  sulphur  is  removed  in  this  way.  The 
granulated  slag  is  run  into  tanks,  from  which  it  is  carried  to  the  mixing 
floor,  as  required,  by  conveyors.  Here  the  slag  is  dumped  into  mixers, 
together  with  thoroughly  slaked  lime  in  a  pasty  condition.  The  lime 
is  obtained  by  the  calcination  of  a  limestone  of  the  following  range  in 
composition : 

Per  Cent. 

Silica  (SiO2) 0.2  to    0.6 

Alumina  ( A12O3) ^02"     08 

Iron  oxide  (Fe2O3) / 

Lime  carbonate  (CaCO3) 97.0  "  98.4 

Magnesium  carbonate  (MgCO3) 0.9"     1.9 

The  mixture  is  then  molded  into  shape  under  pressure  in  a  brick- 
machine  with  a  capacity  of  1000 "bricks  per  hour.  These  bricks  are 
taken  to  the  drying  house,  where  they  remain  about  eight  days,  at  the 
end  of  which  time  they  are  sufficiently  hard  to  stand  transportation. 
In  the  size  usually  made,  the  dry  bricks  weigh  about  4.75  kgs.  each, 
and  will  stand  a  pressure  of  18  kgs.  per  square  centimeter.  In  color  they 
vary  from  nearly  white  to  grayish.  Cement  and  mortar  adhere  to 
them  as  well  as  to  clay  bricks. 

Occasionally  bricks  are  made  at  this  plant  from  slags  of  the  follow- 
ing average  composition,  derived  from  the  smelting  of  a  manganiferous 
ore  different  from  that  commonly  used  at  these  furnaces: 

Per  Cent 

Silica  (SiO2) 33 .00 

Alumina  (A12O3) 18.67 

Iron  oxide  (FeO) 1 .00 

Manganese  oxide  (MnO) 4 . 25 

Lime  (CaO). , 40.00 

Magnesia  (MgO) 2.33 

Sulphur  (S) 1 .33 

Bricks  made  from  this  slag  are  dark  colored,  owing  to  the  compara- 
tively large  percentage  of  manganese  present.  More  lime  must  be  used, 


SLAG  BRICKS   AND  SLAG   BLOCKS.  679 

in  proportion  to  the  slag,  and  the  bricks  made  from  this  slag  require 
a  longer  time  to  dry  and  harden  than  is  needed  by  those  made  from 
the  ordinary  slag. 

Slag  bricks  are  made  at  Ekaterinoslav,*  Russia,  from  blast-furnace 
slags  showing  the  following  range  in  composition: 

Per  Cent 

Silica  (SiO2) 22.5  to  35.0 

Alumina  (A12O3) 14.0  "  15.0 

Iron  oxide  (Fe2O3) 1.1"     3.3 

Manganese  oxide  (MnO) 0.0"     0.3 

Lime  (CaO) 45.0  "  51.0 

Magnesia  (MgO) tr.    "     1.4 

Sulphur  (S) 0.3"     0.4 

Loss  on  heating 2.3"     7.5 

The  slag  is  granulated,  sieved  on  a  revolving  screen,  dried,  and 
ground  in  a  ball  mill.  Lime  is  slaked  and  sieved.  Enough  of  this 
slaked-lime  powder  is  added  to  the  slag  to  bring  the  lime  (CaO)  con- 
tent of  the  mixture  up  to  about  55  per  cent.  With  slags  of  the  range 
in  composition  above  indicated,  this  would  require  the  mixture  to  con- 
sist of  from  5  to  12  parts  of  lime  to  100  parts  of  slag.  The  mixing  is 
carried  on  in  a  screw  mixer,  and  the  powdered  mix  is  then  pressed  into 
brick  in  a  dry  press.  On  issuing  from  this  press  the  bricks  are  set  aside 
to  harden,  and  at  the  end  of  six  days  are  usually  hard  enough  for  use. 
Their  tensile  strength  is  about  312  Ibs.  per  square  inch;  and  the  crush- 
ing strength  varies  from  1250  to  5600  Ibs.  per  square  inch;  both,  of 
course,  increasing  with  age.  The  bricks  are  gray  in  color,  well  shaped, 
weigh  less  than  stone,  and  require  little  mortar  in  laying  up.  They 
withstand  temperature  changes  well,  and  are  particularly  well  adapted 
for  use  in  damp  situations  or  under  water. 

Toldt  has  described,  the  manufacture  of  slag  bricks  at  Bilbao, 
Spain,  where  the  blast-furnace  slag  from  the  Vizcaya  furnaces  is  used. 
Slag  cement  is  made  by  mixing  three  parts,  of  granulated  and  dried 
slag  with  one  part  powdered  slaked  lime,  and  grinding  this  mixture 
in  a  ball  mill.  The  bricks  are  then  made  by  mixing  one  part  by  volume 
of  this  cement  with  four  parts  of  wet  granulated  slag,  and  pressing 
this  mixture  into  shape  in  a  brick-press.  A  Belgian  form  of  press 
with  twelve  molds  is  used.  This  turns  out  twenty  bricks  per  minute, 
with  thirteen  workmen. 

It  will  be  noted  that  in  a  slag  brick  made  in  this  fashion  the  strength 
of  the  brick  must  be  almost  entirely  derived  from  the  slag  cement  used 
in  the  mixture,  for  the  uncrushed  slag  will  be  almost  inert. 

*  Engineering  and  Mining  Journal,  1896. 


680  CEMENTS,  LIMES,  AND   PLASTERS. 

Hardening  in  steam-cyLnders. — A  new  method  of  slag-brick  manu- 
facture has  recently  been  introduced  *  in  Eng  and.  In  this  process 
the  use  of  lime  is  dispensed  with  (except  when  slags  carrying  less  than 
35  per  cent  CaO  are  used),  while  a  hardening  cylinder  is  employed  exactly 
as  in  the  manufacture  of  lime-sand  brick  (see  pp.  136-140).  The  slag  is 
allowed  to  cool  normally;  it  is  then  broken  up  and  fed  to  an  edge-runner 
mill,  where  it  is  crushed  and  ground,  and  falling  thence  into  a  deep 
pit  under  the  mill,  it  is  collected  by  an  elevator  and  thrown  on  a 
10-mesh  screen.  All  capable  of  passing  this  goes  to  the  mixer,  the 
coarser  particles  being  rejected  and  returned  to  the  mill  for  further 
grinding.  "The  ground  slag  is  moistened  in  the  mixer  with  from  5  to 
10  per  cent  of  water,  and  is  then  delivered  by  the  mixer  into  the  brick- 
making  machine,  where  it  is  molded  into  bricks  under  great  pressure, 
the  pressure  employed  being  from  100  to  150  tons  on  each  brick.  As 
the  bricks  are  made  they  are  stacked  onto  steel  platform-wagons  made 
to  carry  from  700  to  800  bricks.  The  loaded  wagons  are  allowed  to 
stand  for  twelve  hours,  to  allow  the  bricks  to  take  a  slight  initial  set, 
after  which  they  are  run  into  the  steel  chamber,  and  the  bricks  are  here 
subjected  to  the  action  of  steam  at  a  pressure  of  from  105  to  120  Ibs. 
per  square  inch.  Ten  hours  under  this  treatment  is  sufficient  to  harden 
the  bricks  and  render  them  on  withdrawal  ready  for  building  purposes. 

"  It  is  necessary  that  the  machinery  employed  should  be  of  a  very 
strong  and  durable  character.  For  effecting  the  grinding  an  edge-run- 
ner mill  is  most  suitable,  as  it  is  not  easily  put  out  of  order  by  the  iron 
which  is  often  found  in  the  slag  in  large  pieces.  The  roller  rims  and 
false  bottom  should  be  of  steel,  preferably  manganese  steel;  and  the 
perforated  grate  should  also  be  of  steel .  the  rollers  should  be  made 
of  a  suitable  weight,  depending  upon  the  hardness  of  the  slag — generally 
from  three  to  five  tons  each.  Their  width  should  not  exceed  12  inches. 

"  A  specially  designed  brick-making  machine  is  employed.  This  con- 
sists of  a  rotating  table  containing  the  molds,  a  feeding-pan,  and  power- 
ful toggle-press.  As  the  table  revolves,  the  molds  pass  alternately  under 
the  feeding-pan  where  they  are  fed  with  the  charge  of  material,  then 
under  the  press,  and  a  further  rotation  brings  the  mold  over  the  ejecting 
plunger  and  the  brick  is  discharged  ready  for  removal.  The  machine 
is  capable  of  exerting  a  pressure  on  each  brick  of  150  tons,  and  is  fitted 
with  a  simple  contrivance  to  insure  the  corners  of  the  bricks  being  well 
pressed  up.  Its  operation  is  first  to  give  the  material  in  the  mold  at 


*  Sutcliffe,  E.  R.     Utilization  of  blast-surface  slag.     Amer.  Mfr.  and  Iron  World, 
vol.  74,  pp.  555-563,  May  5,  1904. 


SLAG   BRICKS  AND  SLAG  BLOCKS.  681 

a  top  pressure  by  means  of  a  wedge-shaped  plunger,  forcing  the  mate- 
rial well  into  the  sides  and  corners  of  the  mold,  and  a  final  pressure 
from  below,  which  completely  presses  out  the  indentation  made  by 
the  wedge-shaped  plunger  and  gives  a  good  finish  to  the  sides  and  cor- 
ners of  the  brick.  The  necessity  of  this  arrangement  will  be  apparent 
when  it  is  understood  that  ground  slag  does  not  become  plastic  under 
pressure  as  does  ordinary  clay,  and  that  a  material  when  filled  into  a 
mold  by  gravity  naturally  piles  in  the  center,  and  if  directly  pressed 
would  produce  bricks  of  greater  density  in  the  center  than  at  the 
sides. 

"The  hardening-chamber  s  like  a  boiler  without  flues,  45  ft.  long 
by  6  ft.  in  diameter.  In  contains  6000  bricks,  and  must  be  capable  of 
withstanding  the  pressure  of  steam,  which  is  used  for  their  indurating. 
One  end  of  the  chamber  is  removable  and  held  in  place  by  hinged  bolts 
threaded  on  to  a  back  ring,  the  joint  being  made  by  a  projection  on 
the  cover  fitting  into  a  recess  in  the  shell,  the  bottom  of  the  recess 
being  filled  with  ordinary  red  rope  packing.  The  chamber  will  per- 
mit of  two  steamings  per  day — one  during  the  daytime  and  the  other 
at  night.  Hence  each  chamber  with  high-pressure  steam  serves  for 
12,000  bricks  per  day. 

"  The  brick  wagons  must  be  strongly  constructed,  as  any  deflection 
of  the  platform  might  tend  to  crack  and  spoil  the  bricks,  which  in  the 
green  state  require  some  care  in  handling.  It  is  necessary  that  roller 
or  ball  bearings  be  used  for  the  axles,  as  under  the  action  of  the  steam 
any  oil  or  grease  would  be  burnt  out  of  ordinary  bearings. 

"  It  will  be  noted  that  no  binding  material-  whatever  is  mixed  with 
the  slag.  The  process  is  really  the  production  of  a  concrete.  In  grind- 
ing the  slag  fine  enough  to  pass  a  10  per  inch  mesh  a  very  large  pro- 
portion of  it  is  reduced  to  a  fine  dust,  which  acts  as  a  hydraulic  cement, 
the  coarser  particles  forming  the  aggregate.  Where  the  slag  is  very 
hard,  and  consequently  only  a  small  proportion  of  dust  is  produced,  it 
is  necessary  to  reduce  a  portion  in  a  ball  mill  or  other  suitable  fine-grind- 
ing machine.  The  precise  action  which  takes  place  during  the  harden- 
ing is  difficult  to  determine;  but  evidently  the  result  is  due  to  a  com- 
bination being  effected  between  the  free  lime  found  in  all  limy  slags 
and  the  silica  and  alumina. 

"  It  may  be  assumed  that  the  silicious  compounds  in  the  slag  become 
soluble  in  the  presence  of  heat  and  moisture,  in  which  condition  it  is 
readily  attacked  by  the  free  lime  present  in  the  slag. 

"  With  some  slags  high-pressure  steam  gives  better  results  than  low- 
pressure,  besides  requiring  less  time  to  effect  the  hardening.  In  speak- 


6S2  CEMENTS,  LIMES,  AND   PLASTERS. 

ing  of  high-pressure  steaming,  it  is  to  be  understood  that  this  refers 
to  any  pressure  above  the  atmosphere  and  low  pressure  to  at  or  under 
this.  With  other  slags  low  pressure  is  quite  as  effectual  as,  and  in  some 
instances  is  better  than,  high  pressure.  To  determine  which  is  the  most 
suitable  process  is  a  question  for  experiment  with  the  particular  slag. 
Where  low-pressure  steaming'  is  adopted  the  chambers  may  either  be 
made  of  thin  sheet  steel  or  tunnels  may  be  constructed  of  brickwork. 
In  the  author's  experiments  a  steel  high-pressure  chamber  was  used 
steaming  up  to  150  Ibs.  pressure  per  square  inch  a*nd  for  low  pressure 
a  chamber  constructed  of  brickwork.  In  general,  for  low-pressure  steam- 
ing for  about  forty  hours,  and  for  high-pressure  steaming  twenty  hours, 
will  be  found  most  suitable  and  convenient.  The  author  has  not  formed 
a  definite  opinion  as  to  what  element  in  the  slag  causes  the  different 
effect  in  the  action  of  high-  and  of  low-pressure  steam,  but  is  inclined 
to  think  that  it  is  principally  due  to  the  proportion  of  sulphur  in  the 
slag.  During  the  steaming  some  sulphur  is  driven  out  of  the  bricks, 
and  the  final  hardening  does  not  seem  to  be  completed  until  this  vola- 
tile or  unfixed  sulphur  is  driven  out  or  combined.  It  is  probable  that 
the  sulphide  of  calcium  present  is  slowly  being  split  up,  the  hydrogen 
of  the  water  combining  with  the  sulphur  forming  sulphuretted  hydro- 
gen, and  the  oxygen  with  the  calcium*  forming  lime.  By  subjecting 
the  slag  to  steam,  thus  keeping  it  moist  and  hot  at  the  same  time,  this 
action  is  accelerated. 

"  Generally  slags  high  in  sulphur^can  be  hardened  best  under  pro- 
longed low-pressure  steam,  and  in  one  or  two  instances  no  hardening 
effect  was  produced  by  high-pressure  steam,  whereas  low-pressure  steam 
produced  the  desired  effect.  From  this  it  would  seem  that  the  chemical 
action  is  only  accelerated  up  to  a  certain  temperature,  and  that  at  a 
higher  temperature  a  different  effect  is  produced;  or  it  may  be  that 
at  a  higher  temperature  the  action  is  too  violent,  causing  an  expansion 
and  separation  of  the  particles  without  actually  producing  cracks  or 
disintegration  of  the  bricks,  but  sufficient  to  prevent  the  final  com- 
bination. Seemingly  the  presence  of  this  unfixed  sulphur  retards  the 
action  of  the  lime  on  the  silicates  and  aluminates,  and  only  when  it  is 
finally  driven  off  can  the  full  combination  be  effected. 

"  In  the  case  of  a  slag  which  falls  to  powder  on  exposure  to  the  atmos- 
phere a  grinding-mill  is  unnecessary;  and  with  some  slags  of  this 
character  it  is  only  necessary  to  moisten  and  then  press  it  into  bricks 
and  harden  as  before.  Again,  with  others  it  would  be  necessary  to 
grind  a  portion  to  dust  in  a  ball  mill  before  the  setting  could  be  obtained. 
In  the  former  case  the  slag  powder  would  consist  of  a  fine  dust  mixed 


SLAG   BRICKS  AND  SLAG   BLOCKS. 


683 


with  coarser  particles,  and  in  the  latter  case  it  would  be  like  a  fine  even- 
grained  sand  without  any  really  fine  dust. 

"  The  slag  used  for  brickmaking  should  preferably  be  new;  but  it 
has  been  found  that  a  slag  which  had  been  exposed  for  twenty  years 
still  possessed  setting  properties  when  acted  upon  by  steam.  One  of 
the  bricks  exhibited  was  made  in  the  summer  of  1901  from  slag  which 
had  been  exposed  to  the  atmosphere  for  over  twenty  years. 

"  In  the  case  of  a  slag  which  disintegrates  on  exposure  to  the  atmos- 
phere, it  would  not  be  wise  to  use  it  directly  after  it  has  cooled  unless 
the  ground-moistened  slag  is  permitted  to  stand  until  the  free  lime  is 
thoroughly  hydrated.  This  could  be  effected  in  silos  erected  directly 
over  the  brickmaking  machine;  and  twenty-four  hours  in  this  condi- 
tion would  be  sufficient.  In  general  the  better  plan  would  be  to  allow 
the  slag  to  stand  for  about  ten  days  before  being  used,  as  in  such  cases 
the  grinding  would  be  facilitated  by  the  disintegrating. 

"  The  slag  for  brickmaking  should  preferably  be  cast  in  thin  layers 
capable  of  being  easily  broken  up  in  sizes  suitable  for  being  passed  into 
the  grinding-mill,  rendering  a  stone-breaker  unnecessary. 

"  The  bricks  are  almost  perfect  in  form,  there  being  no  twisting  or 
distortion  produced  by  the  induration,  and  in  strength  and  other 
qualities  they  will  compare  with  the  best  qualities  of  clay  bricks. 

TABLE  252. 
CRUSHING  STRENGTH  OF  INDURATED  SLAG  BRICKS. 


No.  of 
Specimens. 

Dimensions  in  Inches. 

Cracked  at 
Tons  per  Sq.Ft 

Crushed  at 
Tons  per  Sq.Ft 

Remarks. 

1 

9X4fX2£ 

227 

340 

1 

9  X  4f  X  2} 

303 

375 

Not  completely  crushed 

1 

9X4f  X2£ 

227 

375 

Not  completely  crushed 

1 

9  X  4f  X  2  1 

246 

370 

"  Objections  have  been  raised  against  granulated  slag  bricks  on  account 
of  their  porosity,  which  ranges  in  some  cases  as  high  as  15  per  cent.  No 
objections  of  this  kind  can  be  raised  against  these  indurated  slag  bricks, 
the  absorption  being  remarkably  low,  as  shown  in  Table  253. 

"  The  bricks  before  testing  were  thoroughly  dried  at  212°  and  then 
immersed  for  twenty-four  hours. 

TABLE  253. 
POROSITY  OF  SLAG  BRICKS. 


No. 

Dimensions  in 
Inches. 

Weight    Before 
Immersion. 

Weight  After 
Immersion. 

Gain  in 
Weight. 

Pef  Cent. 

1 
2 

9  X  4f  X  2^ 
9X4fX2| 

8  Ibs.     10  oz. 
8  Ibs.     12  oz. 

9  Ibs.     1  oz. 
9  Ibs.     4  oz. 

7   OZ. 
8  oz. 

5.07 
5.71 

684  CEMENTS,  LIMES,  AND  PLASTERS. 

"  These  bricks  were  tested  by  burning  them  in  an  ordinary  continu- 
ous brick  kiln,  and  a  brick  treated  in  this  way  withstood  the  fire  suc- 
cessfully and  is  still  a  good  hard  brick,  the  only  change  being  in  the 
color,  which  is  now  a  light  buff.  During  the  burning  the  loss  in 
weight  averaged  6  ounces,  which  equals  4.47  per  cent;  and  the  absorp- 
tion after  burning  was  16-  ounces,  or  11.9  per  cent,  after  ^twenty-f  our 
hours'  immersion. 

"  The  following  is  the  estimated  cost  of  production,  based  on  a  pro- 
duction of  10,000  bricks  per  day  of  ten  hours: 


Labor.  £  s.  d. 

1  man  at  grinding-mill  at  6d.  per  hour 0  5  0 

2  men  at  brickmaking  machine,  taking  off,  at  6d. 

per  hour 0  10  0 

1  youth  attending  to  moistening  of  material 0  3  6 

4  wheelers  and  stackers  at  6d.  per  hour 1  0  0 

1  foreman.  .  060 


246 
Cost  in  labor  per  1000  bricks,  say  4s.  6d. 

"  To  this  must  be  added  the  cost  of  getting  the  slag  to  the  machinery, 
wear  and  tear,  depreciation,  and  such  charges  as  may  be  added  for 
power  and  steam. 

11  As  regards  the  slag,  this  should  be  run  from  the  furnaces  on  to  a 
level  floor  and  then  broken  up  and  taken  to  the  machinery.  This  will 
mean  a  little  extra  cost  over  that  of  running  the  slag  in  wagons  and 
depositing  it  in  balls  on  the  slag  heap;  but  6d.  per  ton  should  cover  the 
whole  cost  of  casting  the  slag  in  this  way  and  running  it  to  the  machinery. 
Wear  and  tear  on  machinery  will  necessarily  be  high,  considering  the 
wearing  action  of  the  slag.  This  will  be  well  provided  for  at  Is.  6d. 
per  1000  bricks. 

"  As  to  power  and  steam,  this  would  be  generated  from  the  furnace 
gases,  and  if  not  used  for  this  purpose  might  be  considered  as  wasted; 
but  assuming  this  at  the  value  of  coal,  if  such  were  used  we  should  require 
2|  tons  of  coal  per  day,  which,  at  10s.  per  ton,  works  out  at  2s.  6d.  per 
1000  bricks.  If  we  allow  6d.  per  1000  for  generation,  we  get  3s.  per 
1000  bricks.  • 

"  The  cost  of  a  complete  plant  such  as  described  would  be  about  £3000, 
including  buildings  and  all  requirements.  Taking  depreciation  at  7J 
per  cent  on  the  whole,  and  reckoning  on  300  working  days,  we  get  15s. 
per  day,  or  Is.  6d.  per  1000  bricks. 


SLAG   BRICKS  AND  SLAG  BLOCKS.  685 

SUMMARY  OF  COST  OF  PRODUCTION  PER  1000  BRICKS. 

s.  d. 

Cost  of  labor 4  6 

Slag  at  6d.  per  ton  (4  tons) 2  0 

Wear  and  tear 1  6 

Power  and  steam 3  0 

Depreciation 1  6 

Oils,  sundries,  etc 0  6 


Total  cost  of  production 13    0 

"  The  above  calculation  is  based  on  only  producing  10,000  bricks 
per  day.  The  plant  would  be  capable  of  making  up  to  12,000  per  day; 
so  that  by  only  calculating  on  this  reduced  output  sufficient  allow- 
ance is  made  for  unforeseen  losses.  If  a  larger  plant  were  installed  the 
cost  could  be  very  considerably  reduced;  on  a  plant  producing,  say, 
20,000  bricks  per  day,  the  cost  per  1000  should  not  be  more  than  10s. 
to  11s. 

"This  refers  more  particularly  to  limy  slags;  but  in  the  case  of  slags 
not  so  rich  in  lime,  hydrated  lime  can  be  added  to  the  ground  slag  and 
the  hardening  effected  in  the  same  way,  but  in  such  cases  the  cost  of 
production  is  increased  by  the  cost  of  this  added  lime. 

"  As  before  pointed  out,  most  limy  slags  have  setting  properties  with- 
out being  steamed;  and  with  slags  containing  from  40  to  48  per  cent 
of  lime,  bricks  may  be  made  by  merely  grinding  and  pressing  the  mate- 
rial and  permitting  the  bricks  to  stand  out  in  the  open  air,  the  same 
conditions  being  observed  as  in  making  granulated  slag  bricks,  but 
this  method  is  not  so  satisfactory  as  the  hardening  by  steam.  In  many 
slags  there  is  a  proportion  of  soluble  salts  which  tend  to  spoil  the  bricks 
when  allowed  to  harden  naturally  by  appearing  as  efflorescence.  This  in 
some  cases  is  so  violent  that  the  outer  crust  will  be  forced  away  from 
the  brick;  but  the  same  effect  does  not  happen  when  they  are  steamed, 
the  steaming  either  turning  the  salts  into  a  stable  compound  or  driving 
them  off. 

"  These  bricks  will  withstand  the  weather  equally  with  a  high-class 
clay  brick.  Bricks  have  been  exposed  to  the  weather  the  whole  winter 
and  no  effect  whatever  is  noticeable  upon  them.  They  have  been  soaked, 
then  frozen,  and  afterwards  put  into  hot  water  without  deterioration." 

Slag  Blocks. 

Under  this  heading  will  be  considered  all  these  products  ("slag 
blocks",  "slag  tiles",  etc.)  made  by  running  molten  slag,  direct  from 
the  furnaces,  into  molds  of  proper  shape.  The  term  slag  block  will 
be  employed  as  a  general  but  distinctive  name  for  this  class  of  products 


686  CEMENTS,  LIMES,  AND   PLASTERS. 

in  order  to  distinguish  them  from  the  slag  bricks  made  by  mixing  granu- 
lated slag  with  slaked  lime,  which  have  been  discussed  in  previous  sec- 
tions of  this  chapter. 

Slag  blocks,  if  properly  made,  are  stronger  than  slag  bricks.  They 
are,  however,  impervious  to  air  and  moisture;  and  on  that  account 
are  not  good  building  materials,  for  dwellings  constructed  of  them  are 
apt  to  be  damp  and  unhealthful.  :Their  chief  uses  are  for  foundations 
or  for  paving  blocks,  for  the  latter  of  which  they  are  particularly  well 
adapted. 

Many  smelters  and  furnaces  have  made  small  amounts  of  slag  blocks 
for  local  use.  For  the  past  thirty  years  or  so  a  considerable  quantity 
have  been  made  in  the  Lehigh  iron  district  of  Pennsylvania,  their  earliest 
recorded  use  being  in  the  slag-block  pavements  laid  in  Philadelphia 
about  1876. 

The  properties  required  in  a  slag  block  to  be  used  for  paving  work 
are  density,  resistance  to  abrasion,  toughness,  and  roughness  of  surface. 
These  properties  are  found  to  vary  with  the  chemical  composition  of 
the  slag,  the  rapidity  with  which  the  slag  is  allowed  to  cool,  and  the 
character  of  the  moulds  used.  By  properly  varying  the  last  two  factors, 
slags  of  almost  any  composition  can  be  utilized  in  this  industry. 

The  three  requisite  properties  first  mentioned — i.e.,  density,  resist- 
ance to  abrasion,  and  toughness — vary  directly  with  the  rate  of  cooling, 
the  slowly  cooled  blocks  being  the  best.  Blocks  cast  in  sand  molds 
and  heavily  covered  with  loose  sand,  cool  very  slowly,  and  give  very 
much  better  results  than  those  cast  in  iron  molds.  Slowness  in  cooling, 
however,  requires  much  greater  storage  space  than  if  rapid  cooling  is 
practiced;  and  casting  in  sand  molds  demands  a  higher  grade  of  work- 
manship than  casting  "n  iron  molds. 

The  roughness  of  surface — or  non-slipperiness — of  blocks  intended 
for  paving  use  is  highly  important,  especially  as  slipperiness  has  been 
the  chief  defect  charged  against  slag  blocks,  which  defect  is  prevalent 
in  blocks  cast  in  iron  moulds.  In  English  practice  it  has  been  overcome 
by  casting  the  block  in  a  double  size  mold,  having  a  projection  inside 
which  results  in  a  notch  on  the  slag  block.  The  block  is,  after  coating, 
split  apart  at  this  notch,  and  the  rough  fracture-surface  of  each  half 
is  laid  uppermost  in  paving.  This  method  of  avoiding  slipperiness  adds 
considerable  to  the  labor  cost  of  the  blocks,  and  is  therefore  not  well 
adapted  to  American  practice.  Slag  blocks  cast  on  a  sand  bed  are 
free  from  the  defect  noted  (slipperiness);  or  at  least  it  can  be  avoided 
if  sufficiently  coarse  sand  be  used. 

Slag  blocks  manufactured  by  the  Tees  Scoria  Brick  Company,  of 


SLAG  BRICKS  AND   SLAG   BLOCKS.  687 

Middle.sborough,  England,  have  been  somewhat  extensively  employed  * 
as  street  pavement  in  Rotterdam.  Holland  clay  bricks,  limestone 
blocks,  and  porphyry  bricks  are  employed  in  the  same  city,  and  will 
be  useful  for  comparison  with  the  slag  blocks.  The  foundation,  in 
all  cases,  is  simply  a  bed  of  sand,  carefully  packed.  The  thickness  or 
depth  of  pavement  laid  on  this  varies,  according  to  the  paving  mate- 
rial, as  follows :"  Clay  bricks,  4J  inches;  slag  blocks,  5  inches;  limestone 
or  porphyry  blocks,  6  inches.  The  cost  of  material  and  laying  per 
square  yard  is:  Clay  bricks,  62^  cents;  limestone  blocks,  62^  cents 
to  $1.25;  slag  blocks,  $1.25;  porphyry  blocks,  $1.56.  No  data  as  to 
proportions  of  each  pavement  in  use,  or  durability  of  the  different  types, 
are  available.  The  adjunct  director  of  public  works  of  Rotterdam 
stated  that  for  light  traffic  the  clay-brick  pavements  were  regarded 
as  the  best;  for  medium  traffic,  slag  blocks  or  limestone;  for  heavy 
traffic,  porphyry  blocks. 

The  manufacture  of  slag  blocks  from  copper  slags  at  Mansfeldt, 
Saxony,  has  been  described  f  in  detail  by  Egleston.  The  industry,  as 
carried  on  in  this  locality,  presents  certain  features  of  interest  which 
warrant  a  somewhat  lengthy  abstract  of  the  paper  cited. 

The  slags  used  are  high  in  silica,  ranging  from  40  per  cent  to  60  per 
cent.  When  cooled  rapidly,  they  form  a  dark  colored  brittle  glass, 
but  if  cooled  with  great  slowness  the  product  becomes  gray  and  crystal- 
line. These  slowly  cooled  slags  arc  both  hard  and  tough,  and  there- 
fore serviceable  in  the  manufacture  of  structural  hiaterial.  The  process 
employed  at  Krug  Hutte  is  as  follows: 

The  slag,  as  it  comes  from  the  furnaces,  is  carried  in  slag  wagons 
to  the  molding  ground,  where  the  bricks  are  cast.  The  bed  of  the 
molds  is  sand,  which  has  been  sieved  to  remove  coarse  particles. 

The  bed  is  then  carefully  gone  over  with  a  shovel,  which  is  pressed 
into  it  an  inch  or  so  to  make  the  sand  soft.  It  is  then  smoothed  over 
with  the  shovel,  and  into  the  corners  a  piece  of  iron  QOL.8*m..to  0.20  m. 
long,  and  0.15  m.  wide  is  laid,  inclined  so  as  to  facilitate  the  passage 
of  the  slag  in  the  slag-runners  which  go  round  the  whole  space. 

The  molding-bed  io  then  so  divided  by  iron  partitions  pushed  down 
into  the  sand  as  to  give  the  size  of  blocks  required.  These  partitions 
have  several  round  holes,  about  0.05  m.  in  diameter,  near  their  tops, 
to  permit  the  entrance  of  slag.  Previous  to  use,  the  partitions  are 
washed  with  clay  and  sprinkled  with  sand  to  prevent  the  slag  from 

*  Streets  and  Highways  in  Foreign  Countries.  Special  Consular  Report,  vol. 
3,  p.  190,  Washington,  1897. 

f  School  of  Mines  Quarterly,  vol.  12,  pp.  112-117. 


688  CEMENTS,  LIMES,  AND  PLASTERS. 

sticking  to  them.  Around  each  of  the  molds  thus  formed  is  a  space 
0.20  m.  wide,  through  which  the  slag  flows.  When  all  the  partition's 
are  in  place,  the  bottom  of  each  mold  is  made  flat  by  pressing  down 
into  it  a  piece  of  sheet  iron  (of  the  same  size  as  the  compartment), 
attached  to  a  handle. 

When  the  molds  are  ready  slag  is*  brought  from  the  furnace  in  slag 
wagons,  and  allowed  to  flow  through  the  interspaces  and  into  the  molds. 
When  the  slag  has  about  half  filled  a  mold,  a  little  sand  is  thrown  on 
it  to  prevent  too  rapid  cooling.  When  the  molds  are  entirely  full, 
they  are  covered  with  about  a  foot  of  sand  and  allowed  to  stand  for 
forty-eight  hours.  At  the  end  of  this  time  the  slag  is  cool,  the  sand 
is  shoveled  off,  and  the  iron  partitions  removed. 

During  rainy  weather  the  molding  ground  is  kept  covered  with 
boards  until  the  slag  is  ready  for  pouring,  and  as  soon  as  this  operation 
is  finished  the  molds  are  again  covered  with  boards. 

The  blocks  are  usually  cubes,  0.15  m.  on  the  edge,  though  larger 
sizes  and  different  shapes  are  occasionally  cast.  The  material  which 
has  solidified  in  the  spaces  between  the  molds  is  broken  up  for  use  as 
road  metal. 

At  Koch  Hutte  similar  processes  are  employed.  Large  blocks, 
however,  are  cast  in  cast-iron  molds,  with  a  cover  that  is  shut  down 
in  order  to  compress  the  slag.  Similar  work  is  carried  on  at  Kupfer- 
kammer  Hutte. 

Analyses  of  typical  slags  from  the  Mansfeldt  district  are  given  in 
Table  251. 

A  very  interesting  example  of  the  manufacture  of  slag  blocks  or 
tiles  from  a  copper  blast-furnace  slag  has  been  described  *  by  Braden 
as  having  been  seen  in  operation  at  a  furnace  located  near  Santiago 
de  Chile.  His  description  is  as  follows: 

The  slag  and  matte  are  tapped  from  the  blast-furnace  into  a  slag- 
pot.  After  settling  for  a  few  moments  the  slag  is  poured  from  ladles 
into  molds  which  are  6  inches  square  and  1  inch  deep.  The  molds 
after  being  filled  with  slag  are  placed  on  a  hearth  which  has  a  movable 
cover,  and  covers  are  placed  on  the  molds  as  well  as  on  the  hearth. 
A  very  light  heat  is  kept  up,  so  that  the  slag  cools  very  slowly.  When 
it  appears  black  the  molds  are  lifted  from  the  hearth  and  the  slag  tiles 
are  dumped  into  cold  water.  The  tiles  thus  made  are  very  light  and 
portable.  When  laid  they  have  proven  to  be  tough  and  durable. 
For  this  manufacture  a  slag  carrying  a  considerable  excess  of  iron 

*  Trans.  Am.  Inst.  Min.  Engrs.,  vol.  26,  pp.  52-53.     1896. 


SLAG   BRICKS  AND  SLAG   BLOCKS. 


TABLE  254. 
ANALYSES  OF  SLAG,  MANSFELDT. 


Krug 
Hutte. 

Koch 
Hutte. 

Eckhardt 
Hutte. 

Kupferkammer  Hutte. 

Year      

1888 
Per  Cent. 
18.35 
6.732 
14.825 
4.725 
0.697 
0.063 
1.165 
0.232 
0.289 
47.63 

1888 
Per  Cent. 
23.187 
2.22 
17.001 
4.643 
0.328 
tr. 
0.692 
0.118 
0.277 
48.465 

1888 
Per  Cent. 
21.51 
0.847 
16.525 
2.768 
0.744 
tr. 
0.934 
tr. 
0.3 
46.39 

1881 

Per  Cent. 
19.29 
3.23 
16.35 
10.75 

1.26 

0.75 

48.22 

1881 
Per  Cent. 
20.29 
4.37 
15.67 
8.73 

l.ll 

0.67 
50.0 

Magnesia                          

Alumina           ...... 

Iron  oxide            

Zinc  oxide  

Lead  oxide 

Copper  oxide 

Silica                      

Fluor        

Total   

97.708 

96.931 

90.018 

99.85 

100.84 

Kupferkammer  Hutte. 

Sangerhausen  Hutte. 

1881 
Per  Cent. 
19.50 
8.02 
18.17 
5.89 

1888 
Per  Cent. 
19.15 
3.677 
17.636 
7.213 
0.827 
0.038 
2.056 
0.065 
0.333 
46.81 

1881 
Per  Cent. 
33.10 
1.67 
4.43 
4.37 

0.25 
53.83 
2.09 

1881 
Per  Cent. 
23.40 
0.87 
7.83 
7.47 

.30 
57.43 
1.97 

Lime  

Alumina  

Iron  oxide 

Manganese  oxide 

Nickel  and  cobalt  oxides  

Zinc  oxide     

3.57 

Lead  oxide  

Copper  oxide  

0.23 
48.38 
0.99 

Silica  

Fluor  

Total  

99.75 

97.802 

99.74 

99.27 

has  been  preferred.     The  tiles  are  sold  for  from  $30  to  $60  (pesos  Chilenos) 
per  thousand. 

Slag  blocks  have  been  manufactured  at  a  Montana  copper  smelter 
by  a  process  which  contrasts  strongly  with  the  practice  at  Mansfeldt 
and  Santiago.  The  copper  slag  was  poured  into  iron  molds  built  up 
by  putting  together  iron  plates  of  proper  form.  The  process  was  carried 
on  in  the  open  air  and  no  covering  of  any  kind  was  placed  on  the  blocks. 
The  slag  in  consequence  cooled  very  rapidly.  Though  the  product 
was,  therefore,  not  as  dense  or  tough  as  that  secured  at  Mansfeldt,  the 
Montana  practice  effected  a  great  saving  of  time  and  space. 


INDEX. 


Aalborg  kiln,  recommended  for  natural  cement,  225 
used  for  lime-burning,  101-103 
Portland  cement,  474 

Abrasion,  resistance  to,  by  slag-cements,  670 
Absorption-,  of  clay  bricks,  145 

lime-sand  bricks,  142,  143,  144,  145 
sandstones,  142,  146 
Accelerators  for  plasters,  50,  64,  66 

slag-cement,  659 
Acidity  index,  definition  of,  299 

,  see  also  Silica-alumina  ratio 
Adhesive  strength  of  plasters,  62 
Alabaster,  15 

Algfr,  aid  in  marl  deposition,  338 
Alit,  in  Portland-cement  clinker,  568,  571,  573 
Alkalies,  effect  in  Portland  cement,  310,  388,  391 
in  flue-dust  of  cement-kilns,  510 

limestones,  310 
used  as  accelerator  for  slag  cement,  659 

flux  in  Portland  cement,  391 
Alkali  waste,  analyses  of,  349 

,  used  as  Portland-cement  material,  348-350 
Alum,  used  in  manufacturing  Keene's  cement,  76 
Alumina  bricks,  for  kiln-linings,  490 
Alumina,  clays  high  in,  491 

,  effect  of,  in  Portland-cement  mixtures,  298,  299,  387,  573 

in  sea-water,  602 
silica-alumina  ratio  in  clays,  354 

limestones,  313 
Portland  cement,  299 
Ammonia  process,  see  Alkali  waste. 
Analyses  of  alkali  waste,  349 

alumina  brick  for  kiln-linings,  491 

anthracite  ash,  396 

arenes,  637 

ash  of  coke  and  coal,  396 

691 


692  INDEX. 

Analyses  of  ash,  volcanic,  633-636 

brick  for  kiln -linings,  491,  492 
calcined  magnesite,  155 
cement,  grappier,  185 

,  natural,  253-262,  286 
,  Portland,  397,  575,  577-579 
,  puzzolan,  662,  667,  66£ 
,  slag,  662,  667,  668 
"cement"  plaster,  57 
chalks,  321 

clays  for  kiln-brick,  491.  492 

clays  for  Portland  cement,  325,  350,  355-357,  359,  365,  390,  397 
coal  ash,  396 

coal  ash  for  rotary  kilns,  506,  508,  512,  513 
coke  ash,  396 

fire-brick  for  kiln-linings,  491,  492 
flint  pebbles  for  tube  mills,  465 
flue-dust,  510 
fuel-ash,  393 
gas,  natural,  523 
,  producer,  525 
,  waste  from  rotary  kilns,  507 
gas-coke  ash,  396 
grappiers,  182,  185 
grappier  cements,  185 
gypsite,  54 
gypsum  earth,  54 
gypsum  used  in  making  Keene's  cement,  77 

plasters,  53,  54 
Portland  cement,  545 
hard-finish  plasters,  77 
high-alumina  clays  for  kiln-brick,  491 
high-calcium  limes,  116 
hydraulic  lime,  175,  179,  182,  188 
hydraulic  lime  used  in  slag  cement,  653,  654,  662 
hydraulic  lime-rock,  175,  176,  177,  187 
Keene's  cement,  77 
kiln-brick,  491,  492 
kiln-coals,  506,  508,  512,  513 
kiln -gases,  507 
Lafarge  cement,  185 
lean  limes,  118 
Lehigh  cement  rock,  326,  329 
lime,  95,  116,  118,  119 

hydraulic,  175,  179,  182,  188 

used  in  slag  cement,  653,  654,  662 
.lime,  used  in  slag  cement,  653,  654,  662,  678 
lime-sand  brick,  142 
limestones,  magnesian,  122,  157,  321 


INDEX.  693 

Analyses  of  limestones,  used  for  making  hydraulic  lime,  175-177,  187 

lime,  122 
magnesia,  157 
natural    cement,    204-206,    208-211,   213, 

215,  217 
Portland  cement,  314,  321,  326,  329,  333, 

342 

,  see  also  Chalk,  Marl, 
magnesia,  155,  157,  158 
magnesia  brick,  161 
magnesian  limes,  119 
magnesian  limestones,  157,  327 
magnesite,  152,  153 

calcined,  155 
marls,  342,  390,  397 

natural  cement,  American,  253,  254,  255,  256,  257,  258,  259,  260,  286 
,  Austrian,  262 
,  Belgian,  261 
,  English,  261 
,  French,  261 
,  German,  262 

natural-cement  rock,  American,  204,  205,  206,  208,  209,  210,  211,  213 
,  Belgian,  215 
,  English,  217 
natural  gas,  523 
"natural  Portland"  cement,  Belgium,  261 

rock,  Belgian,  215 
old  Portland  cements,  575 
oyster-shell  lime,  95 
oyster-shells,  95 

Parker's  cement,  see  Natural  cements, 
pebbles,  flint,  465 

plaster,  used  in  Portland  cement,  545 
plasters,  44,  57 
Portland  cement,  American,  397,  577,  578,  579 

,  old,  575 

Portland-cement  mixtures,  394,  397,  506 
pozzuolana,  633,  634,  635 
producer-gas,  525 
puzzolan  cements,  662,  667,  668 
puzzolanic  materials,  633  to  638,  643 
Roman  cements,  see  Natural  cements, 
santorin,  636 
shales,  see  Clays, 
shell-lime,  95 
shells,  95 

slag  cement,  662,  667,  668 
slags,  average  blast-furnace,  351 
,  for  Portland  cement,  352 


694  INDEX. 

Analyses  of  slags,  for  slag  blocks,  689 

s!a~  bricks,  678,  679 
slag  cement,  643,  662,  663 

slate,  roofing,  364 

,  used  for  Portland  cement,  365 

stack-gases,  507 

stucco,  57  '-'  .  ^ 

tetin,  635 

tosca,  635 

trass,  636 

tube-mill  pebbles,  465 

volcanic  ash,  633-636 

waste  gases  from  kiln-stack,  507 

water  from  slag  granulation,  648 
Analytical  methods,  576-582 
Anhydrite,  15 

Anthracite  ash,  analysis  of,  396 
Ash  of  fuel,  analysis  of,  396 
Atlas  cooling  system  for  clinker,  529 
Atlas  plant,  costs  at,  559 
Atomic  weights  of  elements,  table  of,  11 
Austria,  natural  cements  of,  analyses,  262 

Ball  mills,  425,  452-457 
,  Bonnot,  452 
,  Gates,  452 
,  Jensch,  658 
,  Krupp,  455 
,  Smidth,  516 
Basic  slags,  641 

Belit,  in  Portland-cement  clinker,  569 
Berthelet  separator,  245 
Blake  crushers,  24,  238,  430 

see  also  Crushers. 
Blatchley,  W.  S.,  on  intermittent  lime-kilns,  99,  100 

origin  of  marl  deposits,  337 

Bleininger,  A.  V.,  on  fineness  of  natural  cements,  247 

Portland  cement,  585 
Portland-cement  mix,  425 
Blocks,  slag,  685-689 
Blood  as  retarder  for  plaster,  64 
Boilleau  and  Lyon,  on  costs  of  Portland  cement,  558 

slag  cement,  663 
Bonnot  ball  mill,  452 
Bonnot  tube  mill,  457 
Borax  used  in  hard-finish  plasters,  32 
Breakers,  rock,  see  Crushers. 
Brick,  alumina,  for  kiln-linings,  490-492 
magnesia,  160-162 


INDEX.  695 


Brick,  sand-lime,  130-147 

slag,  675-685 
Brick-press,  for  sand-lime  brick,  138 

slag  brick,  678,  679,  680 

Brigham,  S,  T.,  on  strength  of  hydrated  lime,  128 
Brines,  as,  sources  of  magnesia,  158,  159 
British  thermal  unit  defined,  12 
Broughton  mixers,  50 
Buhrstones,  35,  239-243,  437 
Burners,  for  coal,  486-489 

natural  gas,  489,  490 
Burning,  see  Kilns,  Fuels. 

Cactus,  used  as  plaster-retarder,  65 
Calcination,  see  Calciners,  Fuels,  Kilns. 
Calcined  plaster,  32 
Calciners,  kettle,  for  plasters,  37-46 
,  oven,  for  plasters,  37 
,  rotary,  for  plasters,  46-50 
Calcium  carbonate,  see  Limestones. 
Calcium  chloride  as  retarder  for  cement,  546,  54? 
Calcium  oxide,  see  Lime. 
Calcium  hydrate,  see  Lime,  hydrated. 
Calcium  hydroxide,  see  Lime,  hydrated. 
Calorie  denned,  12 

Campbell,  E.  D,,  on  fineness  of  cement  grinding,  424 
Campbell  kiln  for  natural  cement,  225-228 
Campbell  lime-hydrater,  126 
Canada,  gypsum  deposits,  25 

magnesite  deposits,  152 
Candlot,  E.,  on  dome  kilns,  471 

Aalborg  kilns,  475 

composition  of  fuel-ash,  396 
Carbon  dioxide,  in  limestones,  97 

by-product  from  lime-kilns,  108 

from  magnesite,  155 
Carbonate  of  calcium,  see  Limestone. 
Carbonate  cementing  materials,  5-7 
Carbonate  of  lime,  see  Limestone. 
Carbonate  of  magnesium,  see  Magnesite. 
Carbonic  acid,  see  Carbon  dioxide. 
Carpenter,  R.  C,,  on  tests  of  rotary  kilns,  508-510 
effects  of  plaster,  541 

lime  chloride,  546 

Caustic-soda  waste  as  Portland-cement  material,  348-350 
Caustic  soda,  used  in  slag  cement,  659 
Celit,  in  Portland -cement  clinker,  568,  571,  573 
Cementation  index;  calculation  of,  170 

explanation  of,  170,  171 


696  INDEX. 

Cementation  index;  hydraulic  limes,  170-173,  176,  180,  182,  187 
natural  cements,  196-201,  214 
Portland  cements,  391-393,  397 
slag  cements,  656-667 

Cementing  materials,  classification  of,  2-10 
,  production  in  U.  S.,  2 

" Cement"  plasters,  analyses  of, -'57  ^ 

definition  of,  32 
manufacture  of,  31-55 
properties  of,  56-67 

Chamber-kiln  for  lime  and  cement,  106-108,  472-474  ». 

Charcoal,  as  rotary  kiln-fuel,  526 
Chemical  analyses,  see  Analyses. 
Chemical  analysis,  methods  of,  576-582 
Chemical  compounds,  table  of,  12 
Chemical  elements,  table  of,  11 
Chert,  see  Flint. 
Clark  pulverizer,  243 

Classification  of  cementing  materials,  2-10 
Classification  of  crushing  machinery,  429-430 
Clays;  analyses  of,  355,  356,  357,  359,  491,  492 
origin  of,  353 

used  for  kiln-brick,  490-492 
used  in  Portland  cement  manufacture,  353-363 
Clinker  cooling,  527-530 
Clinker  grinding,  530-534 
Closson  process,  158 
Coal  for  kilns,  analyses  of,  513 

,  cost  of  preparation,  520 
,  crushing  and  pulverizing,  514-520 
,  distribution  of,  513 
,  drying  of,  515 
,  explosion  and  fire  risks,  520 
,  treatment  of,  514-522 
Coke  ash,  analysis  of,  396 
Complex  cementing  materials,  6 
Composition,  chemical,  see  Analyses. 
Compressive  strength;  of  clay  bricks,  145 

hydraulic  limes,  183,  189,  190 
lime-sand  bricks,  142-146 
natural  cements,  274-275 
plasters,  61-62 
Portland  cement,  588-592 
puzzolan  cements,  670-671 
sand  cement,  594,  596,  597 
sandstones,  146 
selenitic  limes,  192-193 
slag  bricks,  678,  679,  683 
silica  cement,  594,  596,  597 


INDEX.  697 


Compress! ve  strength;  of  slag  cements,  670-671 
Constitution  of  hydraulic  limes,  172-176 

natural  cements,  195-199,  223 
plasters,  31-32 
Portland  cement,  566-575 
slag  cement,  667 

Cost  of  burning  lime,  106,  108,  109-112 
natural  cement,  248-250 
plasters,  52 

Portland  cement,  558-561 
Cost  of  dredging  marl,  379-381 
Cost  of  drying  cement  materials,  378 
coal,  520 

slag,  649,  663,  664 

Cost  of  erecting  Portland-cement  plant,  555-557 
Cost  of  excavating  cement  rock,  219-221,  378-379 
clay,  373 

gypsum,  29,  30,  52 
limestone,  379     , 
marl,  379-381 

natural-cement  rock,  219-221 
Portland-cement  materials,  378-381 
shale  with  steam-shovel,  373 
Cost  of  fuel,  see  Cost  of  burning. 
Cost  of  labor  in  lime  plants,  106,  108,  110-112 
natural-cement  plants,  248-250 
plaster  plants,  52 
Portland-cement  plants,  558-559 
Cost  of  land  and  quarries,  Portland  cement,  555 
Costs,  of  manufacturing  cement  plaster,  52 
hydrated  lime,  128 
lime,  106,  108,  110-112 
lime-sand  brick,  140-142 
natural  cement,  248-250 
oxychloride  cements,  167 
plaster  of  Paris,  52 
Portland  cement,  554-561 
slag  bricks,  684-685 
slag  cement,  663-664 
Sorel  stone,  167 

Cost  of  mining,  see  Cost  of  excavating. 
Cost  of  plant  for  hydrated  lime,  128 
lime-sand  brick,  140 
Portland  cement,  555-557 
slag  brick,  684  . 

Cost  of  preparing  coal  for  kiln  use,  520 
Cost  of  quarrying,  see  Cost  of  excavating. 
Crackers,  35,  239,  430 
Creighton,  Prof.,  on  strength  of  natural  cements,  276 


698  INDEX. 

Crushers,  Blake,  34,  238,  430 

,  cone-grinders,  34,  238,  430-433 

,  crackers,  35,  239,  430 

,  definition  of  group,  429-430 

,  Gates,  34,  238,  431-433 

,  gyratory,  34,  238,  431-433 

,  jaw,  34,  238,  430  ? 

,  McEntee,  239,  430 

,  Mosser,  430 

,  nippers,  34 

,  rotary,  238,  430-433 

,  Sturtevant,  125,  238 

,  used  for  coal,  514 

gypsum,  34 
lime,  125 

natural  cement,  221,  238 
plaster,  34 

Portland  cement,  429-433,  530 
Crushing  machinery,  classification  of,  429-430 
for  coal,  514-520 
gypsum,  34-37 
lime,  124-125 
natural  cement,  236-247 
plaster,  34-37 

Portland-cement  clinker,  422-468,  530-535 
Portland-cement  materials,  404-410,414,417-418,422-468 
slag  cement,  657-658 
slaked  lime,  124-125 

see  also  Crushing  practice,  Crushers,  Ball  mills,  Tube  mills, 
Kominuters,     Rolls,     Mills,    Mill-stones,     Edge-runners, 
Crackers. 
Crushing  practice,  general  discussion,  422-428 

types  of  machinery  used,  238,  429-430 
use  of  separators,  245,  426-428 
see  also  Crushing  machinery,. 
Cummer  calciner  for  plaster,  46-48 
Cummings  mill,  241-243 
Cyclone  pulverizer,  238 

Cylinders,  hardening,  for  lime-sand  brick,  139-140 
slag  brick,  680-682 

Davidsen  tube  mill,  457-462 

see  also  Tube  mills. 

Davis,  C.  A.,  on  origin  of  marl  deposits,  337,  338,  340 
Deval,  L.,  on  effect  of  alumina,  602 
Dietzsch  kiln,  474 

Dodge  process  for  lime-hydrating,  125 
Dolomite,  composition  of,  6,  90-91 

see  also  Limestones,  Magnesian, 


INDEX.  699 

Dome  kiln,  for  lime,  99 

Portland  cement,  470-471 
Dredging,  cost  of,  379-381 

marl,  357-376,  379-381 
Dryers,  Edison,  402-403 

,  for  slag,  649-652 

limestone,  shale,  etc.,  400-404 

,  Hoist,  651-652 

,  rotary,  400-401,  649-652 

,  Ruggles-Coles,  401,  649-651 

,  tower,  402-403 

,  Vitry,  652 

,  Cummer,  see  Calciners,  rotary. 
Drying  Portland-cement  materials,  378,  399-404 
Dr^y-pans,  437-438 
Dyckerhoff,  Prof.,  on  effect  of  plaster,  539,  541,  543 

Edge-runner  mills,  243,  437-438 
Edison  drier,  401 
kiln,  484 
rolls,  435-437 

Eldred  process  of  lime-hydrating,  125 
Elements,  chemical,  table  of,  11 
Emery  mill,  35,  239-241 
England,  natural  cements  of,  217,  261 
Estrichgips,  68-76 
Examination  of  chalk  deposits,  321 

clay  deposits,  360 

limestone  deposits,  315-318,  321 

marl  deposits,  343-346 

shale  deposits,  360 
Excavation  of  raw  materials,  see  Costs,  Dredging,  Mining,  Quarrying. 

Felit,  in  Portland-cement  clinker,  569 
Ferric  oxide,  formula,  12 

,  see  qlso  Iron  oxide. 
Ferrous  oxide,  formula,  12 

,  see  also  Iron  oxide. 
Fiber-machine,  for  wall-plaster,  51 
Fineness,  of  coal  for  kiln  fuel,  515 

marl,  340 

natural  cement,  236-237,  246-247,  282 

Portland  cement,  531,  584-585,  606 

Portland-cement  mixture,  423-425 

plasters,  58-59 

raw  materials  for  Portland  cement,  423-425 

sand  cement,  592-593 

sand  used  in  lime-sand  brick,  134-135 


700  INDEX. 

Fineness,  of  slag  cement,  657-658,  673 
Fire-brick,  for  kiln-linings,  490-492 
Flint,  in  limestones,  91,  309 

pebbles  for  tube  mills,  461-462,  463-465 
Flooring-plaster,  32,  68-76 
France,  flint  pebbles  from,  463-465 

natural  cements  of,  analyses,  261     ^ 
Fuel  consumption;  in  hydraulic-lime  kilns,  177 

lime-kilns,  98-99,  101,  103,  106 
magnesia-kiln,  154-155 
natural-cement  manufacture,  233-235  *- 
plaster  manufacture,  52 

Portland-cement  manufacture,  492-496,  497-511 
rotary  dryers,  403,  651 

Fuels,  preparation  of  coal  for  rotary  kiln,  514-520 
suggested  use  of  charcoal  in  rotary  kiln,  526 
used  in  Portland-cement  manufacture,  512-526 
use  of  coal  in  rotary  kiln,  486-489,  512-522 
use  of  producer  gas  in  rotary  kiln,  489-490,  524-526 
use  of  natural  gas  in  rotary  kiln,  489-490,  522-524 
use  of  oil  in  rotary  kiln,  522 
see  also  Fuel  consumption. 

Gas,  natural,  in  rotary  kiln,  489-490,  522-524 

,  producer,  in  rotary  kiln,  489-490,  524-526 
Gates  ball  mill,  452-454 

crusher,  34,  238,  425 
tube  mill,  457 
Germany,  natural  cements  of,  analyses,  262 

plaster  manufacture  in,  49-50,  68-76 
Gillmore,  Q.  A.,  on  Hoffmann  kilns,  106-107 
Sorel  stone,  163-167 
crackers,  239 

Glue,  used  as  plaster-retarder,  64 
Grant,  on  tests  of  selenitic  limes,  191-193 
Granulating  slag,  644-648 
Grappier  cements,  analyses  of,  185 
definition  of,  185 
manufacture  of,  185 
properties  of,  185-186 
Grappiers,  analyses  of,  182,  185 

definition  of,  180,  185 
Greenland,  flint  pebbles  from,  463-465 
Greensand  marls,  335 
Griffin  mill,  243,  404,  425,  440-443,  516 
Grimsley,  G.  P.,  on  setting  of  plasters,  64 

costs  of  plaster  manufacture,  52 
Gypsite,  see  Gypsum  earth. 
Gypsum,  analyses  of,  53,  54 


INDEX.  701 


Gypsum,  composition  of,  14 

,  distribution  of,  16-28 
earth,  analyses,  54 
,  character,  15 
,  methods  of  excavating,  30 
,  excavation  of,  28-30 
,  origin  of,  15 
,  physical  properties,  15 
,  specific  gravity,  15 
,  used  in  natural  cement,  264 

plaster  manufacture,  14-30 
Portland  cement,  534-545 
,  varieties,  15 

Hair,  used  in  wall-plaster,  51 

Hair-picker,  51 

Hale,  D.  J.,  on  prospecting  marl  deposits,  344-346 

Hardening  gypsum,  methods  for,  67 

Hardening-cylinders  for  lime-sand  brick,  138-140 

slag  brick,  680-685 

Hard-finish  "cements,"  see  Hard-finish  plaster. 
Hard-finish  plasters,  analyses,  77 
,  definition,  32 
,  manufacture,  76-78 
,  properties,  78 

Harris  system  of  pumping  marl,  376-377 
Hauenschild  kiln,  475-477 
Heat  consumption,  see  Fuel  consumption. 
Heat  losses  in  rotary  kiln,  502-511 
Heat  requirements  in  burning  lime,  98-99 

Portland  cement,  497-501 
Heat  units,  definition  of,  12 

Helbig,  A.  B.,  on  heat  used  in  rotary  kiln,  505,  509 
Hoffmann  kiln  for  burning  lime,  106-108 

Portland  cement,  472-474 
Huennekes  system,  lime-sand  brick,  143 
Huntingdon  mills,  438-440 

Hurry  and  Seaman  " blast-furnace  "  methods,  415-416 
Hydrate  cementing  materials,  definition,  4 
Hydrated  lime,  cost  of  installation  for,  128 
,  methods  of  making,  124-129 
,  packing  weights,  128 
,  with  Portland  cement,  129 
Hydraulic  index,  defects  of,  169 

,  explanation  of,  1 C9 
of  various  cementing  materials,  169 
,  use  in  classification,  169 
Hydraulic  limes,  analyses,  179,  188 

,  classification  of,  173 


702  INDEX. 

Hydraulic  limes,  definition,  172 

,  manufacture,  174-182 

,  properties,  182-184,  188-190 

,  specific  gravity,  182 

,  used  in  slag  cements,  653-654' 

"Improved"  natural  cement,  259,  263,  268  j> 
Index,  acidity,  299 

,  cementation,  see  Cementation  index. 

,  hydraulic,  sec  Hydraulic  index. 
Iron  disulphide,  see  Pyrite.  • 
Iron  oxide,  in  limestones,  91,  310 

Portland  cement,  383,  388,  569-570,  573-574 

Jaw  crushers,  see  Crushers. 

Jensch  ball  mill,  used  in  grinding  basic  slag,  658 

Johnson  kiln  for  Portland  celnent,  471-472 

Keene's  cement,  analyses,  77 

,  manufacture,  76-77 
,  properties,  78 
Kent  mill,  443-447 
Kettles,  calcining,  for  plasters,  38-46 
Keystone  lime-kiln,  104-106 
Kilns,  Aalborg,  101,  225,  474-475 
,  Campbell,  225-228 
,  chamber,  106-108,  472-474 
,  Dietzsch,  474 

.,  dome,  99-101,  225,  470-471 
,  Edison,  484 

for  hydraulic  limes,  177-178 
for  lime-burning,  99-108 
for  natural  cements,  225-233 
for  Portland  cements,  469-496 
,  Hauenschild,  475-477 
,  Hoffmann,  106-108,  472-474 
,  intermittent,  99-101,  470-471 
,  Johnson,  471-472 
,  Keystone,  104-106 
,  O'Connell,  106-107 
,  Ransome  (rotary),  480-496 
,  ring,  106-108,  472-474 
,  rotary,  480-498 
,  Schofer,  101,225,474-475 
,  Schwarz,  477-478 

Kirkwood  gas-burner  for  cement-kilns,  489-490 
Kominuter,  description,  448-452 

,  used  for  natural  cement,  243,  246 
,  used  for  Portland  cement,  448-452 


INDEX  703 


Krupp  ball  mills,  455-457 
Krupp  tube  mills,  462-463 


Labor,  cost  of,  see  Costs  of  labor. 

Lafarge  cement,  185-186 

Leblanc  process,  see  Alkali  waste. 

Le  Chatelier,  H.,  on  constitution  of  hydraulic  limes,  174-175 

Portland  cement,  569-570,  573,  574 
effect  of  sea-water  on  cement,  601 
expansion  of  magnesia  brick,  161-162 
setting  properties  of  Portland  cement,  572 
Lewis,  F.  H.,  on  effects  of  plaster,  537,  538,  544 
Lignite  used  for  producer-gas,  524-526 
Lime,  effects  in  Portland  cement,  384-386,  496,  566-575 
Lime,  hydrated,  composition  of,  119 

,  manufacture  of,  124-127 
,  methods  of  lime-slaking,  120-122,  124-127 
,  physical  properties  of,  128 
Lime  of  Teil,  see  Hydraulic  limes. 
Lime,  slaked,  see  Limes,  hydrated. 
L*ime  carbonate,  see  Limestones. 
Lime  chloride,  used  as  cement-retarder,  546-547 
Limes,  analyses,  116,  118,  119 
,  classification  of,  97-98 
,  composition,  115-119 
,  costs  of  manufacture,  106,  108,  109-112 
,  fuel  consumption  in  burning,  98-99,  101,  103,  106 
,  groups  of,  97-98 
,  hydraulic,  see  Hydraulic  limes. 
.  kilns  used  for,  99-108 
,  magnesian  vs.  high-calcium,  115 
,  methods  of  manufacture,  98-109 
,  physical  properties,  120-123 
,  raw  materials,  88-95 
,  statistics  of  production,  112-114 

Limestones,  analyses  of,  157,  175-177,  187,  203-213,  215,  217 
,  composition  of,  6,  89 
,  cost  of  excavation,  109,  219-221,  378-379 
,  distribution  of,  91-94 
,  excavating,  109,  219-221,  367-375 
,  impurities  of,  91,  309-310 
,  magnesian,  6,  90-91,  157 
,  mining,  219-221,  375 
,  modules  of,  see  Sepatria. 
,  origin  of,  88-89 
,  properties  of,  310-311 
,  quarrying,  109,  219-221,  367-375 
,  used  for  hydraulic  lime,  175-177,  187 
,  used  for  lime,  88-95 


704  IXDEX. 

Limestones,  used  for  natural  cement,  200-222 

,  used  for  Portland  cement,  307-347 

,  varieties  of,  89 

,  water  contained  in,  378 

see  also  Chalk,  Marl. 
Lindhard  kominuter.  243,  246,  448-452 
Linings  for  rotary  kilns,  490-492-    ,  ^ 

tube  mills,  459 

Mack's  cement,  78 

Magnesia,  analyses  of,  155,  158 

,  carbonate  of,  see  Magnesite. 
,  chemical  formula  of,  97,  148 
,  preparation  of,  148-159 
,  in  limestones,  90,  157 
,  in  limes,  115,  118-119 
,  in  natural  cements,  197,  200 
,  in  Portland  cements,  298,  386,  631 
Magnesia  bricks,  analyses,  161 

,  manufacture,  160-161 
,  properties,  161-162 

Magnesian  limestones,  see  Limestone,  Magnesiao, 
Magnesite,  analyses  of,  152-153 
,  burning  of,  154-155 
,  composition  of,  148-149 
,  distribution  of,  149-152 
,  imports  of,  153 
,  origin  of,  149 
,  production  of,  153 

Magnesium  chloride,  as  source  of  magnesia,  158-159 
use  in  Sorel  stone,  etc.,  162-167 
Mahon,  R.  W.,  on  slags  suitable  for  slag  cement,  642 
Mannheim  system  of  calcining  plaster,  49-50 
Marble,  89 
Marl,  analyses  of,  342 

,  composition  of,  341-343 
,  definition  of,  334 
,  distribution  of,  339-340 

,  dredging  methods  and  costs,  375-377,  379-381 
,  drying,  378 

,  examination  of  deposits,  343-347 
,  greensand,  335 
,  origin  of,  335-339 
,  physical  properties,  340-341 
,  pumping,  376-377 
,  water  contained  in,  343,  378 
,  weight,  340-341 

Marston,  Prof.,  on  tests  of  plasters,  60-64 
McEntee  cracker,  239 


INDEX.  705 

McKenna,  C,,  on  properties  of  Lafarge  cement,  185-186 
Mill,  Cummings,  241-243 

,  emery,  35,  125,  239-241 

,  Griffin,  243,  404,  425,  440-443,  516 

,  Huntingdon,  404,  425,  438-440 

,  Kent,  443-447 

,  Sturtevant,  35,  125,  239-241 

,  Williams,  244-245,  466-468,  516 

see  also  Crushing  machinery. 
Millstones,  125,  239-243,  437 
Mills,  G.  S.,  on  tests  of  lime,  122 
Mining  gypsum,  29 

limestone,  219-221,  375,  379 
natural-cement  rock,  219-221 
see  also  Costs  of  excavation. 
Mixer,  Broughton,  50 

Natural  cements,  analyses,  253-262 

,  compressive  strength,  274 

,  compressive-tensile  ratio,  275-276 

,  cost  of  manufacture,  248-251 

,  definition  of,  195 

,  effect  of  gypsum  or  plaster,  264 

,  effect  of  heat  on  strength,  275 

,  effect  of  salt,  267 

,  fineness,  236-237,  246-247 

,  history,  285-289 

,  methods  of  manufacture,  223-247 

,  modulus  of  elasticity,  277 

,  packing  weights,  248 

,  physical  properties,  262-277 

,  rapidity  of  set,  263 

,  raw  materials  for,  200-222 

,  statistics,  289-292 

,  tensile  strength,  267,  283 
Natural  gas  in  rotary  kilns,  489-490,  522-524 
"Natural  Portland"  cements,  214-217 
Newberry,  S.  B.,  on  change  in  composition  during  burning,  396-397 

constitution  of  Portland  cement,  567,  569,  570,  574 
formula  for  cement  mixtures,  391-393 
heat  used  in  kiln,  505,  509 
Kent  mill,  445 

Nihoul  and  Dufossez,  on  effects,  pf  plaster,  537,  539,  540 
Nippers,  used  in  grinding  gypsum,  34-35 

O'Connell  lime-kiln,  106-107 
Oil  used  in  rotary  kilns,  522 
Organic  matter,  as  retarder  for  plasters,  65 
,  in  marls,  341,  343 


706  INDEX. 

Ovens,  used  in  plaster  manufacture,  37 
Oxychloride  cements,  9,  162-167 

Packing  weights  of  hydrated  lime,  128 
natural  cements,  248 
plasters,  52    . 

Portland  cements,  548-553 
slag  cements,  672 
Parian  "cement",  33 
Parker's  cement,  217 
Pebbles  for  tube  mills,  463-465 

Peppel,  S.  V.,  on  lime-sand  brick,  134-136,  140,  142 
Petroleum  in  rotary  kilns,  522 

Phosphorus,  effects  of,  in  Portland-cement  mixtures,  389-390,  673 
Plaster,  accelerators  for,  50,  64-68 
,  adhesive  strength,  62-63 
t  analyses,  57 
,  classification,  32 
,  compressive  strength,  61-62 
,  cost  of  manufacture,  52 
,  fineness,  58-59 
,  groups  of,  32,  56 
.,  imports  of,  79,  86 
,  manufacturing  methods,  33-55 
,  packing  weights,  52 
,  physical  properties,  57-67 
,  production  of,  79-87 
,  raw  materials  for,  14-30 
,  retarders  for,  50,  64-68 
,  specific  gravity,  57 
,  statistics  of  production,  79-87 
,  tensile  strength,  58-61 
,  used  in  natural  cement,  264 

Portland  cement,  534-545 
,  weight  per  cubic  foot,  57 
Plaster  of  Paris,  definition,  32 

,  see  also  Plaster. 
Porosity,  see  Absorption. 
Portland  cement,  analyses  of,  575,  577-579 
,  analytical  methods,  604 
,  cementation  index  of,  398-399 
,  compressive  strength,  588-589 
,  compressive  tensile  ratio,  589-591 
,  constitution  of,  382-391,  566-582 
,  costs  of  manufacture,  554-561 
,  definition  of,  297 
,  effect  of  freezing,  598-601 
gypsum,  534-545 
heat,  597-598 


INDEX.  707 

Portland  cement,  effect  of  plaster,  534-545 
salt,  598-601 
sea-water,  602-603 
,  fineness,  584-585,  606 
,  methods  of  analysis,  604 
,  methods  of  manufacture,  398-565 
,  modulus  of  elasticity,  591-592 
,  origin  of  names,  294-295 
' ,  packing  weights,  548-553 
,  physical  properties,  582-613 
,  production  of,  561-565 
,  raw  materials  for,  300-381 
,  specific  gravity,  385-386,  605-606 
,  specifications  for,  614-631 
,  tensile  strength,  586-588,  612 
,  use  of  gypsum  or  plaster,  535-545 
Potash,  see  Alkalies. 
Prospecting,  see  Examination. 
Prost,  S.,  on  effects  of  granulating  slag,  648 

slags  suitable  for  slag  cement,  641-642 
Pulverized  coal  as  kiln-fuel,  486-489,  512-522 
Pulverizer,  Clark,  243 

,  Cyclone,  238 
,  Raymond,  466 

Pulverizing  machinery,  see  Crushing  machinery. 
Purington,  C.  W.,  on  use  of  steam-shovels,  373 
Puzzolan  cements,  definition,  9,  632 

,  raw  materials  for,  632-640 
,  see  also  Slag  cement. 
Pyrite  in  limestone,  91,  310,  388 
see  also  Sulphur,  Sulphides. 

Quarrying  clays,  370-375 
gypsum,  28,  30 

limestone,  109,  219-221,  367-375,  378-379 
natural-cement  rock,  219-221 
Portland-cement  material,  367-375,  378-379 
shales,  370-375 

Ransome  kiln,  see  Kiln,  rotary. 

Ratio  between  compressive  and  tensile  strength:  natural  cement,  275-276 

Portland  cement,  589-591 
slag  cement,  670-671 
silica  and  alumina,  see  Alumina,  Index. 

Raymond  pulverizer,  466 

Retarders  for  plasters,  50,  64-66 

Portland  cement,  534-547 

Richards,  J.  W.,  on  tests  of  rotary  kiln,  506,  507,  509 

Richards,  R.  H.,  on  costs  of  crushing,  433 


70S  INDEX. 

Richardson,  C.,  on  constitution  of  Portland  cement,  567-575 
phosphorus  in  cement  mixture,  389 
specific  gravity  of  natural  cement,  263 
Ring  kiln,  106-108,  472-474 
Rock-crushers,  see  Crushers. 
Rock-emery  mill,  35,  125,  239-241 
Rock  excavation,  see  Excavation. 
Rohland,  on  set  of  plasters,  64 
Roman  cements,  214,  217 
Roofing  slate,  see  Slate. 
Rotary  calciner,  see  Calciners. 

drier,  see  Driers. 

kiln,  see  Kiln. 

Sabin,  L.  C.,  on  properties  of  lime,  123 

natural  cement,  263-265,  273,  276 
Portland  cement,  539,  540.  600 
Salt,  brines  as  sources  of  magnesia,  158-159 
,  effect  on  natural  cement,  267 

Portland  cement  598-601 
Sampling,  marl  deposits,  343-346 

see  also  Examination. 
Sand  cement,  592-597 
Sawdust,  used  as  plaster-retarder,  64 
Schiebler  process,  157 
Schofer  kiln  for  lime,  101 

Portland  cement,  473 
Schwarz  kiln,  477-479 

Schwarz  process  for  lime-sand  brick,  136-137 
Scott's  cement,  190-193 
Seasoning  clinker,  235-236 
Sea-water,  as  source  of  magnesia,  158-159 

,  effect  on  Portland  cement,  602-603 
Selenite,  15 
Selenitic  lime,  manufacture,  190-191 

,  properties,  191-193 
Separators,  Berthelet  system,  244-246 
,  in  coal-pulverizer,  520 

natural-cement  plants,  244-246 
Portland-cement  plants,  426-428 
Septaria,  217 

Shales,  analyses  of,  357-379 
,  excavating,  370-374 
,  origin,  353 

Shell-lime,  analyses  of,  95 
Shells,  analyses  of,  95 

,  in  marl  deposits,  339 
,  used  for  lime-burning,  94-95 
Shovel,  steam,  use  of,  370-374 


INDEX.  709 

f5ilex  linings  for  tube  mills,  459 
Silica  cement,  592-597 
Silica,  in  limestones,  309-310 

Portland  cement,  383,  386 
Simple  cementing  materials,  3-7 
Slag-blocks,  analyses  of  slags  used  for,  689 
,  definition,  685 

,  methods  of  manufacture,  C85-689 
,  properties  of,  686 

Slag-bricks,  analyses  of  slags  used  for,  678,  679 
,  definition,  674 

t  methods  of  manufacture,  674-685 
,  properties,  676-679,  683 
Slag  cement,  color  of,  669 

,  composition  of  slags  used,  641-644 

,  costs  of  manufacture,  663-664 

,  methods  of  manufacture,  641,  645-665 

production  of,  664 
,  properties  and  tests,  666-671 
,  specific  gravity,  668-669 
,  specifications  for,  672-674 
,  tensile  strength,  670 
,  see  also  Puzzolan  cements. 
Slags,  used  in  Portland-cement  manufacture,  analyses,  352 

,  methods,  411-415 
slag-cement  manufacture,  analyses,  643 

,  composition,  641-644 
,  drying,  649-652 
,  granulation,  644-648 
,  methods  of  use,  645-665 
Slaked  lime,  see  Lime  hydrate. 
Slaking  lime,  120-122,  126 

natural-cement  clinker,  235-236 
Slate,  analyses  of,  364-365 

,  distribution  of,  363-364 
,  origin  of,  363 

,  used  as  Portland-cement  material,  363-366 

Slosson  and  Moudy,  on  accelerators  and  retarders  for  plasters,  65-67 
temperature  of  plaster  burning,  43-44 
tests  of  plasters,  61-62 
Smidth  ball  mill,  516 
Soda,  used  as  slag-cement  accelerators,  659 

,  see  Alkalies. 
Sorel  stone,  9,  162-167 
Specifications  for  natural  cement,  276-284 
Portland  cement,  614-631 
puzzolan  cement,  672-674 
slag  cement,  672-674 
Specific  gravity,  method  of  determining,  605-606 


710  INDEX. 

Specific  gravity,  of  anhydrite,  15 

"cement  plaster".  57 
grappier  cements,  185 
gypsum,  15 
Keene's  "cement",  77 
Lafarge  cement,  185 
lime,  115 

limestone,  310  f* 

magnesia,  154 
natural  cement,  263-282 
plasters,  57 
Portland  cement,  585 
puzzolan  cement,  668-669 
slag  cement,  668-669 

Stack-dust  from  rotary  kilns,  composition  and  use,  510 
Stack-gases  from  cement-kilns,  composition  of,  507 

,  use  of,  509 

lime-kilns,  use  of,  108-109 
Statistics,  see  Imports,  Production. 

Strength,  see  Adhesive  strength,  Compressive  strength,  Tensile  strength. 
Structural  materials,  production  of,  in  U.  S.,  1 
Stucco,  analyses,  57 
,  definition,  32 
Sturtevant  crusher  for  slaked  lime,  125 

rock-emery  mill,  35,  125,  239-241 
system  of  feeding  powdered  coal,  486-489 
Stedman  disintegrator,  36,  244 
Sulphate  of  lime,  see  Gypsum,  Plasters,  Sulphur, 
Sulphide  of  iron,  see  Pyrite. 
Sulphides,  in  limestones ,'91,  310,  388 

,  presence  in  Portland  cement,  388 
slag  cements,  666-667 
Sulphur,  effect  in  slag  cements,  666  . 
,  in  alkali  waste,  348,  349 
,  in  kiln-coal,  512-513 
,  in  limestones,  91,  310,  388 
,  in  Portland  cements,  388 
,  presence  in  slags,  648-666 
,  removal  by  granulating  slag,  648 
Sulphuric  acid,  see  Sulphur  trioxide. 
Sulphur  trioxide,  in  gypsum,  14 

limestones,  91,  310,  388 

Tankage,  used  as  plaster-retarder,  65 
Teil,  lime  of,  see  Hydraulic-limes. 
Temperature  of  burning  lime,  96-97 

magnesite,  154 

natural  cement,  223-225 

plasters,  31,  41,  44 


INDEX.  711 

Temperature  of  Portland  cement,  499-500 
Tensile  strength,  of  grappier  cements,  186 
hard-finish  plasters,  78 
hydraulic  limes,  183,  188 
Keene's  cement,  78 
Lafarge  cement,  186 
limes,  122-123 
natural  cements,  267,  283 
plasters,  58-61 

Portland  cements,  586-588,  612 
puzzolan  cements,  670,  673 
selenitic  limes,  191 
slag  cements,  670,  673 
Testing  methods,  standard,  603-613 
Tests  of  cementing  materials,  see  Adhesive  strength,  Compressive  strength,  Tensile 

strength, 

Tests  of  efficiency  of  rotary  kiln,  505-509 
Tetmajer,  Prof.,  effects  of  plaster,  543 

tests  of  natural  cement,  266-267 

Portland  cement,  505 
Thermal  efficiency  of  rotary  kiln,  497-511 

units  defined  and  compared,  12 

Thompson,  S.;  on  weight  of  cement  barrels,  551-553 
Travertine,  89 

Tube  mills,  404,  425,  430,  457,  516,  657-658 
,  Bonnot,  457 
,  Davidsen,  244,  457-462 
,  description  of  class,  430,  457 
,  discontinuous,  657-658,  660 
,  Gates,  457 
,  Jensch,  658 
,  Krupp,  457,  462-463 
,  pebbles  for,  463-465 

,  used  in  natural-cement  plants,  237,  243-244,  246 
,  West,  660 
Tufa,  89 
Tuff,  633,  638 

United  States,  imports  of  gypsum,  85-86 

magnesia  and  magnesite,  152-153 

plasters,  85-86 

Portland  cement,  564-565 
lime,  112-114 
magnesite,  152-153 
natural  cement,  289-292 
plasters,  79-84 
Portland  cement,  561-565 
production  of  gypsum,  79-84 
slag  cement,  664 


712  INDEX. 

United  States,  structural  materials,  1 

total  cementing  materials,  2 

Van't  Hoff,  Prof.,  on  constitution  of  flooring  plasters,  69-75 
Vegetable  matter,  as  retarder  for  plaster,  65 

,  in  marls,  effects  of,  341-343 

,  used  in  wall-plaster,  51-52* 

Wall-plasters,  33,  51-52 
Water,  amount  present  in  chalks,  318 
clays,  378 

granulated  slag,  649 
gypsum,  14,  31 
limestones,  378 
marls,  340,  341,  343 
plaster,  31,  44 
shales,  378 

required  in  slaking  lime,  120 
,  sea-,  effect  on  Portland  cement,  602-603 
,  used  in  granulating  slag,  644-648 
Wear,  resistance  of  slag  cement  to  mechanical,  670 
Weight  per  cubic  foot  of  "cement  plaster,"  57 
clay,  305 
lime,  115 

lime-sand  bricks,  142 
limestone,  305,  310 
magnesia  bricks,  161 
marl,  340-341 
plaster,  57 

Portland  cement,  551-553 
shale,  305 

slag  bricks,  678,  683 

,  see  also  Specific  gravity,  Packing  weights. 
Whiting  process,  regulation  of  set  in  slag  cements,  658-659 
Williams  mill,  244-245,  466-468,  516 
Wilder,  F.  A.,  on  flooring  plaster,  75 

rotary  calciners  for  plaster,  49-50 
Wilkinson,  P.,  on  kettle  process  for  plasters,  38-43 
Wood-fiber,  used  in  wall-plaster,  51 
Woolson,  I.,  on  strength  of  clay  bricks,  145 

lime-sand  bricks,  144 


SHORT-TITLE  CATALOGUE 


OF    THE 

PUBLICATIONS 


OF 


JOHN  WILEY   &  SONS 

NEW  YORK 

LONDON:  CHAPMAN    &  HALL,  LIMITED 


ARRANGED   UNDER  SUBJECTS 


Descriptive  circulars  sent  on  application.     Books  marked  with  an  asterisk  (*)  are 
sold  at  net  prices  only.     All  books  are  bound  in  cloth  unless  otherwise  stated. 


AGRICULTURE— HORTICULTURE— FORESTRY. 

Armsby 's  Principles  of  Animal  Nutrition 8vo,  $4  00 

Budd  and  Hansen's  American  Horticultural  Manual: 

Part  I.  Propagation,  Culture,  and  Improvement 12mo,  1  50 

Part  II.  Systematic  Pomology 12mo,  1  50 

Elliott's  Engineering  for  Land  Drainage 12mo,  1  50 

Practical  Farm  Drainage.     (Second  Edition,  Rewritten.) 12mo,  1  50 

Graves's  Forest  Mensuration 8vo,  4  00 

Principles  of  Handling  Woodlands.     (In  Press.) 

Green's  Principles  of  American  Forestry 12mo,  1  50 

Grotenfelt's  Principles  of  Modern  Dairy  Practice.     (Woll.) .  12mo,  2  00 

*  Herrick's  Denatured  or  Industrial  Alcohol 8vo,  4  00 

Kemp  and  Waugh's  Landscape  Gardening.     (New  Edition,  Rewritten.     In 

Press.) 

*  McKay  and  Larsen's  Principles  and  Practice  of  Butter-making 8vo,  1  50 

Maynard's  Landscape  Gardening  as  Applied  to  Home  Decoration 12mo,  1  50 

Sanderson's  Insects  Injurious  to  Staple  Crops 12mo,  1  50 

Sanderson  and   Headlee's   Insects  Injurious  to  Garden  Crops.     (In  Prepa- 
ration.) 

*  Schwarz's  Longleaf  Pine  in  Virgin  Forest, 12mo,  1  25 

Solotaroff's  Shade  Trees  in  Towns  and  Cities.     (In  Press.) 

Stockbridge's  Rocks  and  Soils 8vo,  2  50 

Win  ton's  Microscopy  of  Vegetable  Foods 8vo,  7  50 

Woll's  Handbook  for  Farmers  and  Dairymen 16mo,  1  50 


ARCHITECTURE. 

Baldwin's  Steam  Heating  for  Buildings 12mo,  2  50 

Berg's  Buildings  and  Structures  of  American  Railroads 4to,  5  00 

Birkmire's  Architectural  Iron  and  Steel 8vo,  3  50 

Compound  Riveted  Girders  as  Applied  in  Buildings 8vo,  2  00 

Planning  and  Construction  of  American  Theatres 8vo,  3  00 

1 


Birkmire's  Planning  and  Construction  of  High  Office  Buildings 8vo.  $3  50 

Skeleton  Construction  in  Buildings 8vc,  3  00 

Briggs's  Modern  American  School  Buildings 8vo,  4  00 

Byrne's  Inspection  of  Materials  and  Wormanship  Employed  in  Construction. 

16mo,  3  00 

Carpenter's  Heating  and  Ventilating  of  Buildings 8vo,  4  00 

*  Corthell's  Allowable  Pressure  on  Deep  Foundations 12mo,  1  25 

Fieilag's  Architectural  Engineering 8vo,  3  50 

Fireproofing  of  Steel  Buildings 8vo,  2  50 

Gerhard's  Guide  to  Sanitary- Inspections.  •  (Fourth    Edition,    Entirely    Re- 
vised and  Enlarged.) .' J? 12mo,  1  50 

*  Modern  Baths  and  Bath  Houses '. 8vo,  3  00 

Sanitation  of  Public  Buildings 12mo,  1  50 

Theatre  Fires  and  Panics 12mo,  1  50 

*  The  Water  Supply,  Sewerage  and  Plumbing  of  Modern  City  Buildings. 

8vo,  4  00 

Johnson's  Statics  by  Algebraic  and  Graphic  Methods 8vo,  2  00 

Kellaway's  How  to  Lay  Out  Suburban  Home  Grounds 8vo,  2  00 

Kidder's  Architects'  and  Builders'  Pocket-book 16mo,  mor.,  5  00 

Merrill's  Stones  for  Building  and  Decoration 8vo,  5  00 

Monckton's  Stair-building 4to,  4  00 

Patton's  Practical  Treatise  on  Foundations 8vo,  5  00 

Peabody's  Naval  Architecture 8vc,  7  50 

Rice's  Concrete-block  Manufacture 8vo,  2  00 

Richey's  Handbook  for  Superintendents  of  Construction 16mo,  mor.  4  00 

Building  Foreman's  Pocket  Book  and  Ready  Reference.  .  16mo,  mor.  5  00 
*  Building  Mechanics'  Ready  Reference  Series: 

*  Carpenters'  and  Woodworkers'  Edition 16mo,  mor.  1  50 

*  Cement  Workers'  and  Plasterers'  Edition 16mo,  mor.  1  50 

*  Plumbers',  Steam-Fitters',  and  Tinners'  Edition.  .  .16mo,  mor.  1  50 

*  Stone-  and  Brick-masons'  Edition 16mo,  mor.  1  50 

Sabin's  House  Painting 12mo,  1  00 

Siebert  and  Biggin's  Modern  Stone-cutting  and  Masonry 8vo,  1  50 

Snow's  Principal  Species  of  Wood 8vo,  3  50 

Wait's  Engineering  and  Architectural  Jurisprudence 8vo,  6  00 

Sheep,  6  50 

Law  of  Contracts 8vo,  3  00 

Law  of    Operations  Preliminary  to  Construction    in  Engineering  and 

Architecture 8vo,  5  00 

Sheep,  5  50 

Wilson's  Air  Conditioning 12mo,  1  50 

Worcester  and  Atkinson's  Small  Hospitals,  Establishment  and  Maintenance, 
Suggestions   for    Hospital    Architecture,  with    Plans  for  a    Small 

Hospital 12mo,  1  25 


ARMY  AND   NAVY. 

Bernadou's  Smokeless  Powder,  Nitro-cellulose,  and  the  Theory  of  the  Cellu- 
lose Molecule l2mo,  2  50 

Chase's  Art  of  Pattern  Making 12mo,  2  50 

Screw  Propellers  and  Marine  Propulsion 8vo,  3  00 

*  Cloke's  Enlisted  Specialists'  Examiner 8vo,  2  00 

*  Gunner's  Examiner 8vo,  1  50 

Craig's  Azimuth 4tu,  3  50 

Crehore  and  Squier's  Polarizing  Photo-chronograph 8vo.  3  00 

*  Davis's  Elements  of  Law 8vo,  2  50 

*  Treatise  on  the  Military  Law  of  United  States 8vo,  7  00 

*  Dudley's  Military  Law  and  the  Procedure  of  Courts-martial.  ..Large  12mo,  2  50 
Durand's  Resistance  and  Propulsion  of  Ships 8vo,  5  00 

*  Dyer's  Handbook  of  Light  Artillery 12mo.  3  00 

Eissler's  Modern  High  Explosives 8vo,  4  00 

*  Fiebeger's  Text-book  on  Field  Fortification Large  12mo,  2  00 

Hamilton  and  Bond's  The  Gunner's  Catechism 18mo,  1  00 


*  Hoff's  Elementary  Naval  Tactics 8vo,  $1  50 

Ingalls's  Handbook  of  Problems  hi  Direct  Fire . .  . 8vo,  4  00 

*  Lissak's  Ordnance  and  Gunnery 8vo,  6  00 

*  Ludlow's  Logarithmic  and  Trigonometric  Tables 8vo,  1   00 

*  Lyons's  Treatise  on  Electromagnetic  Phenomena.  Vols.  I.  and  II..8vo,each,  6  00 

*  Mahan's  Permanent  Fortifications.      (Mercur.) 8vo,  half  mor.  7  50 

Manual  for  Courts-martial 16mo,mor.  1   50 

*  Mercur's  Attack  of  Fortified  Places 12mo,  2  00 

*  Elements  of  the  Art  of  War 8vo,  4  00 

Nixon's  Adjutants'  Manual 24mo,  1  00 

Peabody's  Naval  Architecture 8vo,  7  50 

*  Phelps's  Practical  Marine  Surveying 8vo,  2  50 

Putnam's  Nautical  Charts 8vo,  2  00 

Rust's  Ex-meridian  Altitude,  Azimuth  and  Star-Finding  Tables Svo,  5  00 

*  Selkirk's  Catechism  of  Manual  of  Guard  Duty 24mo,  50 

Sharpe's  Art  of  Subsisting  Armies  in  War 18mo,  mor.  1  50 

*Taylor's  Speed  and  Power  of  Ships.     2  vols,    Text  8vo,  plates  oblong  4to,  7  50 

*  Tupes  and  Poole's  Manual  of  Bayonet  Exercises  and  Musketry  Fencing. 

24mo,  leather,  50 

*  Weaver's  Military  Explosives 8vo,  3  00 

*  Woodhull's  Military  Hygiene  for  Officers  of  the  Line Large  12mo,  1  50 


ASSAYING. 

Betts's  Lead  Refining  by  Electrolysis 8vo,  4  00 

*Butler's  Handbook  of  Blowpipe  Analysis 16mo,  75 

Fletcher's  Practical  Instructions  in  Quantitative  Assaying  with  the  Blowpipe. 

16mo,  mor.  1  50 

Furman  and  Pardoe's  Manual  of  Practical  Assaying 8vo,  3  00 

Lodge's  Notes  on  Assaying  and  Metallurgical  Laboratory  Experiments.. 8vo,  3  00 

Low's  Technical  Methods  of  Ore  Analysis 8vo,  3  00 

Miller's  Cyanide  Process 12mo,  1  00 

Manual  of  Assaying 12mo,  1  00 

Minet's  Production  of  Aluminum  and  its  Industrial  Use.      (Waldo.).  ..12mo,  2  50 

Ricketts  arid  Miller's  Notes  on  Assaying Svo.  3  00 

Robine  and  Lenglen's  Cyanide  Industry.      (Le  Clerc.) 8vo,  4  00 

*  Seamen's  Manual  for  Assayers  and  Chemists Large  12mo,  2  50 

Ulke's  Modern  Electrolytic  Copper  Refining Svo,  3  00 

Wilson's  Chlorination  Process 12mo,  1  50 

Cyanide  Processes , , , 12mo,  1  50 


ASTRONOMY. 

Comstock's  Field  Astronomy  for  Engineers Svo,  2  50 

Craig's  Azimuth 4to,  3  50 

Crandall's  Text-book  on  Geodesy  and  Least  Squares Svo,  8  00 

Doolittle's  Treatise  on  Practical  Astronomy Svo,  4  00 

Hayford's  Text-book  of  Geodetic  Astronomy Svo,  3  00: 

Hosmer's  Azimuth 16mo,  mor.  1  00 

*  Text-book  on  Practical  Astronomy Svo,  2  00 

Merriman's  Elements  of  Precise  Surveying  and  Geodesy Svo,  2  50 

*  Michie  and  Harlow's  Practical  Astronomy Svo,  3  00 

Rust's  Ex-meridian  Altitude,  Azimuth  and  Star-Finding  Tables Svo,  5  00 

*  White's  Elements  of  Theoretical  and  Descriptive  Astronomy 12mo,  2  00 


CHEMISTRY. 

*  Abderhalden's   Physiological  Chemistry   in   Thirty   Lectures.      (Hall   and 

Defren.) Svo,  5  00 

*  Abegg's  Theory  of  Electrolytic  Dissociation,     (von  Ende.) 12mo,  1  25 

Alexeyeff's  General  Principles  of  Organic  Syntheses.     (Matthews.) Svo,  3  00 

Allen's  Tables  for  Iron  Analysis Svo,  3  00 

Armsby's  Principles  of  Animal  Nutrition Svo,  4  00 

3 


Arnold's  Compendium  of  Chemistry.     (Mandel.) Large  12mo,  $3  50 

Association  of  State  and  National  Food  and  Dairy  Departments,  Hartford 

Meeting,  1906 8vo,  3  00 

Jamestown  Meeting,  1907 8vo,  3  00 

Austen's  Notes  for  Chemical  Students , 12mo,  1  50 

Baskerville's  Chemical  Elements.     (In  Preparation.) 

Bernadou's  Smokeless  Powder. — Nitro-cellulose,  and  Theory  of  the  Cellulose 

Molecule 12mo,  2  50 

*  Biltz's  Introduction  to  Inorganic  Chemistry.   (Hall  and  Phelan.).  .  .  12mo,  1  25 

Laboratory  Methods  of  Inorganic  Chemistry.     (Hall  and  Blanchard.) 

^                                             8vo,  3  00 

*  Blanchard's  Synthetic  Inorganic  Chemistry.  4 12mo,  1  00 

*  Browning's  Introduction  to  the  Rarer  Elements 8vo,  1  50 

*  Butler's  Handbook  of  Blowpipe  Analysis 16mo,  75 

*  Claassen's  Beet-sugar  Manufacture.     (Hall  and  Rolfe.) 8vo,  3  00 

Classen's  Quantitative  Chemical  Analysis  by  Electrolysis.     (Boltwood.).8vo,  3  00 

Cohn's  Indicators  and  Test-papers k  .  .  12mo,  2  00 

Tests  and  Reagents 8vo,  3  00 

*  Danneel's  Electrochemistry.     (Merriam.) 12mo,  1  25 

Dannerth's  Methods  of  Textile  Chemistry 12mo,  2  00 

Duhem's  Thermodynamics  and  Chemistry.     (Burgess.) 8vo,  4  00 

Effront's  Enzymes  and  their  Applications.     (Prescott.) 8vo,  3  00 

Eissler's  Modern  High  Explosives 8vo.  4  00 

*  Fischer's  Oedema 8vo,  2  00 

*  Physiology  of  Alimentation Large  12mo,  2  00 

Fletcher's  Practical  Instructions  in  Quantitative  Assaying  with  the  Blowpipe. 

16mo,  mor.  1  50 

Fowler's  Sewage  Works  Analyses 12mo,  2  00 

Fresenius's  Manual  of  Qualitative  Chemical  Analysis.     (Wells.) 8vo,  5  00 

Manual  of  Qualitative  Chemical  Analysis.  Part  I.  Descriptive.  ( Wells. )8vo,  3  00 

Quantitative  Chemical  Analysis.     (Cohn.)     2  vols 8vc,  12  50 

When  Sold  Separately,  Vol.  I,  $6.     Vol.  II,  $8. 

Fuertes's  Water  and  Public  Health 12mo,  1  50 

Furman  and  Pardoe's  Manual  of  Practical  Assaying 8vo,  3  00 

*  Getman's  Exercises  in  Physical  Chemistry 12mo,  2  00 

Gill's  Gas  and  Fuel  Analysis  for  Engineers 12mo,  1  25 

*  Gooch  and  Browning's  Outlines  of  Qualitative  Chemical  Analysis. 

Large  12mo,  1  25 

Grotenfelt's  Principles  of  Modern  Dairy  Practice.     (Woll.) 12mo,  2  00 

Groth's  Introduction  to  Chemical  Crystallography  (Marshall) 12mo,  1  25 

Hammarsten's  Text-book  of  Physiological  Chemistry.     (Mandel.) 8vo,  4  00 

Hanausek's  Microscopy  of  Technical  Products.     (Win ton.) 8vo,  5  00 

*  Haskins  and  Macleod's  Organic  Chemistry 12mo,  2  00 

*  Herrick's  Denatured  or  Industrial  Alcohol 8vo,  4  00 

Hinds's  Inorganic  Chemistry 8vo,  3  00 

*  Laboratory  Manual  for  Students 12mo,  1  00 

*  Holleman's    Laboratory    Manual    of    Organic    Chemistry    for    Beginners. 

(Walker.) 12mo,  1  00 

Text-book  of  Inorganic  Chemistry.     (Cooper.) 8vo,  2  50 

Text-book  of  Organic  Chemistry.     (Walker  and  Mott.) 8vo,  2  50 

*  Holley's  Lead  and  Zinc  Pigments Large  12mo,  3  00 

Holley  and  Ladd's  Analysis  of  Mixed  Paints,  Color  Pigments,  and  Varnishes. 

Large  12mo,  2  50 

Hopkins's  Oil-chemists'  Handbook 8vo,  3  00 

Jackson's  Directions  for  Laboratory  Work  in  Physiological  Chemistry.  .8vo,  1  25 
Johnson's  Rapid  Methods  for  the  Chemical  Analysis  of  Special  Steels,  Steel- 
making  Alloys  and  Graphite Large  12mo,  3  00 

Landauer's  Spectrum  Analysis.     (Tingle.) 8vo,  3  00 

Lassar-Cohn's  Application  of  Some  General  Reactions  to  Investigations  in 

Organic  Chemistry.      (Tingle.) 12mo,  1  00 

Leach's  Inspection  and  Analysis  of   Food  with   Special   Reference  to  State 

Control 8vo,  7  50 

Lob's  Electrochemistry  of  Organic  Compounds.     (Lorenz.) 8vo,  3  00 

Lodge's  Notes  on  Assaying  and  Metallurgical  Laboratory  Experiments.. 8vo,  3  00 

Low's  Technical  Method  of  Ore  Analysis ; 8vo,  3  00 

Lowe's  Paint  for  Steel  Structures 12mo,  1  00 

Lunge's  Techno-chemical  Analysis.     (Cohn.) 12mo.  1  00 

4 


*  McKay  and  Larsen's  Principles  and  Practice  of  Butter-making 8vo,  $1  50 

Maire's  Modern  Pigments  and  their  Vehicles 12mo,  2  00 

Mandel's  Handbook  for  Bio-chemical  Laboratory 12mo,  1  50 

*  Martin's   Laboratory  Guide  to  Qualitative  Analysis  with  the  Blowpipe 

12mo,  0  60 

Mason's  Examination  of  Water.     (Chemical  and  Bacteriological.) 12mo,  1   25 

Water-supply.     (Considered  Principally  from  a  Sanitary  Standpoint.) 

8vo,  4  00 

*  Mathewson's  First  Principles  of  Chemical  Theory 8vo,  1  00 

Matthews's  Laboratory  Manual  of  Dyeing  and  Textile  Chemistry 8vo,  3  50 

Textile  Fibres.     2d  Edition,  Rewritten 8vo,  4  00 

*  Meyer's    Determination    of    Radicles    in    Carbon    Compounds.      (Tingle.) 

Third  Edition 12mo,  1  25 

Miller's  Cyanide  Process 12mo,  1  00 

Manual  of  Assaying 12mo,  1  00 

Minet's  Production  of  Aluminum  and  its  Industrial  Use.      (Waldo.).  ..12mo,  2  50 

*  Mittelstaedt's  Technical  Calculations  for  Sugar  Works.  (Bourbakis.)   12mo,  1  50 

Mixter's  Elementary  Text-book  of  Chemistry 12mo,  1  50 

Morgan's  Elements  of  Physical  Chemistry 12mo,  3  00 

Outline  of  the  Theory  of  Solutions  and  its  Results 12mo,  1  00 

*  Physical  Chemistry  for  Electrical  Engineers 12mo,  1  50 

*  Moore's  Outlines  of  Organic  Chemistry 12mo,  1  50 

Morse's  Calculations  used  in  Cane-sugar  Factories 16mo,  mor.  1  50 

*  Muir's  History  of  Chemical  Theories  and  Laws 8vo,  4  00 

Mulliken's  General  Method  for  the  Identification  of  Pure  Organic  Compounds. 

Vol.  I.     Compounds  of  Carbon  with  Hydrogen  and  Oxygen.  Large  8vo,  5  00 

Vol.  II.     Nitrogenous  Compounds.      (In  Preparation.) 

Vol.  III.     The  Commercial  Dyestuffs : Large  8vo,  5   00 

*  Nelson's  Analysis  of  Drugs  and  Medicines 12mo,  3  00 

Ostwald's  Conversations  on  Chemistry.     Part  One.      (Ramsey.) 12mo,  1  50 

Part  Two.      (Turnbull.) 12mo,  200 

Introduction  to  Chemistry.     (Hall  and  Williams.)     (In  Press.) 

Owen  and  Standage's  Dyeing  and  Cleaning  of  Textile  Fabrics 12mo,  2  00 

*  Palmer's  Practical  Test  Book  of  Chemistry 12mo,  1  00 

*  Pauli's  Physical  Chemistry  in  the  Service  of  Medicine.      (Fischer.) .  .  12mo,  1  25 
Penfield's  Tables  of  Minerals,  Including  the  Use  of  Minerals  and  Statistics 

of  Domestic  Production 8vo,  1  00 

Pictet's  Alkaloids  and  their  Chemical  Constitution.      (Biddle.) 8vo,  5  00 

Poole's  Calorific  Power  of  Fuels 8vo,  3  00 

Prescott  and  Winslow's  Elements  of  Water  Bacteriology,  with  Special  Refer- 
ence to  Sanitary  Water  Analysis 12mo,  1  50 

*  Reisig's  Guide  to  Piece-Dyeing 8vo,  25  00 

Richards  and  Woodman's  Air,  Water,  and  Food  from  a  Sanitary  Stand- 
point  8vo.  2  00 

Ricketts  and  Miller's  Notes  on  Assaying 8vo,  3  00 

Rideal's  Disinfection  and  the  Preservation  of  Food 8vo,  4  00 

Sewage  and  the  Bacterial  Purification  of  Sewage 8vo,  4  00 

Riggs's  Elementary  Manual  for  the  Chemical  Laboratory 8vo,  1  25 

Robine  and  Lenglen's  Cyanide  Industry.  (Le  Clerc.) 8vo,  4  00 

Ruddiman's  Incompatibilities  in  Prescriptions 8vo,  2  00 

Whys  in  Pharmacy 12mo,  1  00 

*  Ruer's  Elements  of  Metallography.     (Mathewson.) 8vo,  3  00 

Sabin's  Industrial  and  Artistic  Technology  of  Paint  and  Varnish 8vo,  3  00 

Salkowski's  Physiological  and  Pathological  Chemistry.     (Orndorff.) 8vo,  2  50 

Schimpf 's  Essentials  of  Volumetric  Analysis 12mo,  1.  25 

Manual  of  Volumetric  Analysis.     (Fifth  Edition,  Rewritten) 8vo,  5  00 

*  Qualitative  Chemical  Analysis 8vo,  1  25 

*  Seamon's  Manual  for  Assayers  and  Chemists Large  12mo.  2  50 

Smith's  Lecture  Notes  on  Chemistry  for  Dental  Students 8vo,  2  50 

Spencer's  Handbook  for  Cane  Sugar  Manufacturers 16mo,  mor.  3  00 

Handbook  for  Chemists  of  Beet-sugar  Houses 16mo,  mor.  3  00 

Stockbridge's  Rocks  and  Soils 8vo,  2  50 

Stone's  Practical  Testing  of  Gas  and  Gas  Meters 8vo,  3  50 

*  Tillman's  Descriptive  General  Chemistry 8vo,  3  00 

*  Elementary  Lessons  in  Heat 8vo,  1  50 

Treadwell's  Qualitative  Analysis.     (Hall.) 8vo,  3  00 

Quantitative  Analysis.     (Hall.) 8vo.  4  00 

5 


Turneaure  and  Russell's  Public  Water-supplies .8vo,  $5  00 

Van  Deventer's  Physical  Chemistry  for  Beginners.     (Boltwood.) 12mo,  1  50 

Venable's  Methods  and  Devices  for  Bacterial  Treatment  of  Sewage 8vo,  3  00 

Ward  and  Whipple's  Freshwater  Biology.     (In  Press.) 

Ware's  Beet-sugar  Manufacture  and  Refining.     Vol.  I. 8vo,  4  00 

Vol.  II ...8vo,  5  00 

Washington's  Manual  of  the  Chemical  Analysis  of  Rocks. . .  .^. 8vo,  2  00 

*  Weaver's  Military  Explosives , 8vo,  3,  00 

Wells's  Laboratory  Guide  in  Qualitative  Chemical  Analysis 8vo,  1   50 

Short  Course  in  Inorganic  Qualitative  Chemical  Analysis  for  Engineering 

Students .-.'., .^ 12mo,  1  50 

Text-book  of  Chemical  Arithmetic .; ^ .  12mo,  1  25 

Whipple's  Microscopy  of  Drinking-water 8vo,  3  50 

Wilson's  Chlorination  Process 12mo,  1  50 

Cyanide  Processes 12mo,  1  50 

Wmton's  Microscopy  of  Vegetable  Poods 8vo,  7  50 

Zsigmondy's  Colloids  and  the  Ultramicroscope.     (Alexander.).. Large  12mo,  3  00 


CIVIL    ENGINEERING. 

BRIDGES   AND    ROOFS.     HYDRAULICS.     MATERIALS    OF    ENGINEER- 
ING.     RAILWAY   ENGINEERING. 

Baker's  Engineers'  Surveying  Instruments 12mo,  3  00 

Bixby's  Graphical  Computing  Table Paper  19£  X  24$  inches.  25 

Breed  and  Hosmer's  Principles  and  Practice  of  Surveying.     Vol.  I.  Elemen- 
tary Surveying .' .  .  8vo,  3  00 

Vol.  II.     Higher  Surveying 8vo,  2  50 

*  Burr's  Ancient  and  Modern  Engineering  and  the  Isthmian  Canal 8vo,  3  50 

Comstock's  Field  Astronomy  for  Engineers 8vo,  2  50 

*-Corthell's  Allowable  Pressure  on  Deep  Foundations 12mo,  1  25 

Crandall's  Text-book  on  Geodesy  and  Least  Squares 8vo,  3  00 

Davis's  Elevation  and  Stadia  Tables 8vo,  1  00 

Elliott's  Engineering  for  Land  Drainage 12mo,  1  50 

*  Fiebeger's  Treatise  on  Civil  Engineering 8vo,  5  00 

Flemer's  Photographic  Methods  and  Instruments 8vo,  5  00 

Folwell's  Sewerage.     (Designing  and  Maintenance.) 8vo,  3  00 

Frei tag's  Architectural  Engineering 8vo,  3  50 

French  and  Ives's  Stereotomy 8vo,  2  50 

Goodhue's  Municipal  Improvements 12mo,  1  50 

*  Hauch  arid  Rice's  Tables  of  Quantities  for  Preliminary  Estimates. .  .  12mo,  1  25 

Hayford's  Text-book  of  Geodetic  Astronomy 8vo,  3  00 

Hering's  Ready  Reference  Tables  (Conversion  Factors.) 16mo,  mor.  2  50 

Hosmer's  Azimuth 16mo,  mor.  1  00 

*  Text-book  on  Practical  Astronomy 8vo,  2  00 

Howe's  Retaining  Walls  for  Earth 12mo,  1  25 

*  Ives's  Adjustments  of  the  Engineer's  Transit  and  Level 16mo,  bds.  25 

Ives  and   Hilts's    Problems   in    Surveying,  Railroad  Surveying  and  Geod- 
esy  16mo,  mor.  1  50 

*  Johnson  (J.B.)  and  Smith's  Theory  and  Practice  of  Surveying . Large  12mo,  3  50 
Johnson's  (L.  J.)  Statics  by  Algebraic  and  Graphic  Methods 8vo,  2  00 

*  Kinnicutt,  Winslow  and  Pratt's  Sewage  Disposal 8vo,  3  00 

*  Mahan's  Descriptive  Geometry 8vo,  1  50 

Merriman's  Elements  of  Precise  Surveying  and  Geodesy 8vo,  2  50 

Merriman  and  Brooks's  Handbook  for  Surveyors 16mo,  mor.  2  00 

Nugent's  Plane  Surveying 8vo,  3  50 

Ogden's  Sewer  Construction 8vo.  3  00 

Sewer  Design 12mo,  2  00 

Parsons's  Disposal  of  Municipal  Refuse 8vo,  2  00 

Patton's  Treatise  on  Civil  Engineering .8vo,  half  leather,  7  50 

Reed's  Topographical  Drawing  and  Sketching 4to,  5  00 

Rideal's  Sewage  and  the  Bacterial  Purification  of  Sewage 8vo,  4  00 

Riemer's  Shaft-sinking  under  Difficult  Conditions.  (Corning  and  Peele.).8vo,  3  00 

Siebert  and.  Biggin's  Modern  Stone-cutting  and  Masonry 8vo,  1  50 

6 


Smith's  Manual  of  Topographical  Drawing.      (McMillan.) 8vo,  $2  50 

Soper's  Air  and  Ventilation  of  Subways 12mo,  2  50 

*  Tracy's  Exercises  in  Surveying '. 12mo,  mor.  1  00 

Tracy's  Plane  Surveying 16mo,  mor.  3  00 

*  Trautwine's  Civil  Engineer's  Pocket-book 16mo,  mor.  5  00 

Venable's  Garbage  Crematories  in  America 8vo,  2  00 

Methods  and  Devices  for  Bacterial  Treatment  of  Sewage 8vo,  3  00 

Wait's  Engineering  and  Architectural  Jurisprudence 8vo,  6  00 

Sheep,  6  50 

Law  of  Contracts 8vo,  3  00 

Law  of   Operations   Preliminary  to  Construction   in   Engineering  and 

Architecture.  . , 8vo,  5  00 

Sheep,  5  50 

Warren's  Stereotomy — Problems  in  Stone-cutting 8vo,  2  50 

*  Waterbury's   Vest-Pocket   Hand-book   of  Mathematics   for   Engineers. 

2fX5l  inches,  mor.  1  00 

*  Enlarged  Edition,  Including  Tables mor.  1  50 

Webb's  Problems  in  the  Use  and  Adjustment  of  Engineering  Instruments. 

16mo,  mor.  1  25 

Wilson's  Topographic  Surveying 8vo,  3  50 


BRIDGES   AND  ROOFS. 

Boiler's  Practical  Treatise  on  the  Construction  of  Iron  Highway  Bridges.. 8vo,  2  00 

*  Thames  River  Bridge Oblong  paper,  5  00 

Burr  and  Falk's  Design  and  Construction  of  Metallic  Bridges 8vo,  5  00 

Influence  Lines  for  Bridge  and  Roof  Computations 8vo,  3  00 

Du  Bois's  Mechanics  of  Engineering.     Vol.  II Small  4to,  10  00 

Foster's  Treatise  on  Wooden  Trestle  Bridges 4  to,  5  00 

Fowler's  Ordinary  Foundations 8vo,  3  50 

Greene's  Arches  in  Wood,  Iron,  and  Stone 8vo,  2  50 

Bridge  Trusses 8vo,  2  50 

Roof  Trusses 8vo,  1  25 

Grimm's  Secondary  Stresses  in  Bridge  Trusses 8vo,  2  50 

Heller's  Stresses  in  Structures  and  the  Accompanying  Deformations..  .  .8vo,  3  00 

Howe's  Design  of  Simple  Roof-trusses  in  Wood  and  Steel 8vo.  2  00 

Symmetrical  Masonry  Arches 8vo,  2  50 

Treatise  on  Arches 8vo,  4  00 

*  Jacoby's  Structural  Details,  or  Elements  of  Design  in  Heavy  Framing,  8vo,  2  25 
Johnson,  Bryan  and  Turneaure's  Theory  and  Practice  in  the  Designing1  of 

Modern  Framed  Structures Small  4to,  10  00 

*  Johnson,  Bryan  and  Turneaure's  Theory  and  Practice  in  the  Designing  of 

Modern  Framed  Structures.     New  Edition.     Part  1 8vo,  3  00 

Part  II.     Rewritten.     (In  Press.) 

Merriman  and  Jacoby's  Text-book  on  Roofs  and  Bridges: 

Part  I.      Stresses  in  Simple  Trusses 8vo,  2  50 

Part  II.    Graphic  Statics 8vo',  2  50 

Part  III.     Bridge  Design 8vo,  2  50 

Part  IV.  Higher  Structures 8vo,  2  50 

Sondericker's  Graphic  Statics,  with  Applications  to  Trusses,  Beams,  and 

Arches 8vo,  2  00 

Waddell's  De  Pontibus,  Pocket-book  for  Bridge  Engineers 16mo,  mor.  2  00 

*  Specifications  for  Steel  Bridges 12mo,  50 

Waddell  and  Harrington's  Bridge  Engineering.      (In  Preparation.) 


HYDRAULICS. 

Barnes's  Ice  Formation 8vo,  3  00 

Bazin's  Experiments  upon  the  Contraction  of  the  Liquid  Vein  Issuing  from 

an  Orifice.     (Trautwine.) 8vo,  2  00 

Bovey 's  Treatise  on  Hydraulics 8vo,  5  00 

Church's  Diagrams  of  Mean  Velocity  of  Water  in  Open  Channels. 

Oblong  4to,  paper,  1   50 

Hydraulic  Motors 8vo,  2  00 

7 


Coffin's  Graphical  Solution  of  Hydraulic  Problems IGmo,  mor.  $2  50 

Flather's  Dynamometers,  and  the  Measurement  of  Power 12mo,  3  00 

Folwell's  Water-supply  Engineering 8vo,  4  00 

Frizell's  Water-power 8vo,  5  00 

Fuertes's  Water  and  Public  Health 12mo,  1  50 

Water-filtration  Works 12mo,  2  50 

Ganguillet  and  Kutter's  General  Formula  for  the  Uniform  Flow  of  Water  in 

Rivers  and  Other  Channels.     (Hering  and  Trautwine.) 8vo,  4  00 

Hazen's  Clean  Water  and  How  to  Get  It Large  12mo,  1   50 

Filtration  of  Public  Water-supplies 8vo,  3  00 

Hazelhurst's  Towers  and  Tanks  for  Water-worifs 8vo,  2  50 

Herschel's  115  Experiments  on  the  Carrying  Capacity  of  Large,  Riveted,  Metal 

Conduits 8vo,  2  00 

Hoyt  and  Grover's  River  Discharge 8vo,  2  00 

Hubbard   and   Kiersted's  Water-works   Management   and   Maintenance. 

1.         8vo,  4  00 

*  Lyndon's   Development   and   Electrical   Distribution    of   Water    Power. 

8vo,  3  00 

Mason's  Water-supply.     (Considered    Principally   from   a   Sanitary   Stand- 
point.)   8vo,  4  00 

Merriman's  Treatise  on  Hydraulics 8vo,  5  00 

*  Molitor's  Hydraulics  of  Rivers,  Weirs  and  Sluices 8vo,  2  00 

*  Morrison  and  Brodie's  High  Masonry  Dam  Design 8vo,  1  50 

*  Richards's  Laboratory  Notes  on  Industrial  Water  Analysis 8vo,  50 

Schuyler's  Reservoirs  for  Irrigation,   Water-power,  and  Domestic  Water- 
supply.     Second  Edition,  Revised  and  Enlarged Large  8vo,  6  00 

*  Thomas  and  Watt's  Improvement  of  Rivers 4to,  6  00 

Turneaure  and  Russell's  Public  Water-supplies 8vo,  5  00 

Wegmann's  Design  and  Construction  of  Dams.     5th  Ed.,  enlarged 4to,  6  CO 

Water-Supply  of  the  City  of  New  York  from  1658  to  1895 4io,  10  00 

Whipple's  Value  of  Pure  Water Large  12mo,  1  00 

Williams  and  Hazen's  Hydraulic  Tables 8vo,  1  50 

Wilson's  Irrigation  Engineering 8vo,  4  00 

Wood's  Turbines 8vo,  2  50 


MATERIALS   OF   ENGINEERING. 

Baker's  Roads  and  Pavements 8vo,  5  00 

Treatise  on  Masonry  Construction 8vo,  5  00 

Black's  United  States  Public  Works Oblong  4to,  5  00 

Blanchard's  Bituminous  Roads.      (In  Preparation.) 

Bleininger's  Manufacture  of  Hydraulic  Cement.     (In  Preparation.) 

*  Bovey 's  Strength  of  Materials  and  Theory  of  Structures 8vo,  7  50 

Burr's  Elasticity  and  Resistance  of  the  Materials  of  Engineering 8vo,  7  50 

Byrne's  Highway  Construction 8vo,  5  00 

Inspection  of  the  Materials  and  Workmanship  Employed  in  Construction. 

16mo,  3  00 

Church's  Mechanics  of  Engineering 8vo,  6  00 

Du  Bois's  Mechanics  of  Engineering. 

Vol.    I.  Kinematics,  Statics,  Kinetics Small  4to,  7  50 

Vol.  II.  The  Stresses  in  Framed  Structures,  Strength  of  Materials  and 

Theory  of  Flexures Small  4to,  10  00 

*  Eckel's  Cements,  Limes,  and  Plasters 8vo,  6  00 

Stone  and  Clay  Products  used  in  Engineering.      (In  Preparation.) 

Fowler's  Ordinary  Foundations. . .' 8vo,  3  50 

*  Greene's  Structural  Mechanics 8vo,  2  50 

*  Holley's  Lead  and  Zinc  Pigments Large  12mo,  3  00 

Holley  and  Ladd's  Analysis  of  Mixed  Paints,  Color  Pigments  and  Varnishes. 

Large  12mo,  2  50 

*  Hubbard's  Dust  Preventives  and  Road  Binders 8vo,  3  00 

Johnson's  (C.  M.)  Rapid  Methods  for  the  Chemical  Analysis  of  Special  Steels, 

Steel-making  Alloys  and  Graphite Large  12mo,  3  00 

Johnson's  (J.  B.)  Materials  of  Construction Large  8vo,  6  00 

Keep's  Cast  Iron 8vo,  2  50 

Lanza's  Applied  Mechanics 8vo,  7  50 

Lowe's  Paints  for  Steel  Structures 12mo,  1  00 

8 


Maire's  Modern  Pigments  and  their  Vehicles 12mo,  $2  00 

Maurer's  Technical  Mechanics 8vo,  4  00 

Merrill's  Stones  for  Building  and  Decoration .' .  ,8vo,  5  00 

Merriman's  Mechanics  of  Materials .* 8vo,  5  00 

*  Strength  of  Materials 12mo,  1  00 

Metcalf 's  Steel.     A  Manual  for  Steel-users 12mo,  2  00 

Morrison's  Highway  Engineering „ .    .  „ . .  8vo,  2  50 

Patton's  Practical  Treatise  on  Foundations 8vo,  5  00 

Rice's  Concrete  Block  Manufacture 8vo,  2  00 

Richardson's  Modern  Asphalt  Pavement 8vo,  3  00 

Richey's  Building  Foreman's  Pocket  Book  and  Ready  Reference.  16mo,mor.  5  00 

*  Cement  Workers'  and  Plasterers'  Edition  (Building  Mechanics'  Ready 

Reference  Series) 16mo,  mor.  1  50 

Handbook  for  Superintendents  of  Construction 16mo,  mor.  4  00 

*  Stone    and     Brick    Masons'     Edition    (Building    Mechanics'    Ready 

Reference  Series) 16mo,  mor.  1   50 

*  Ries's  Clays :   Their  Occurrence,  Properties,  and  Uses 8vo,  5  00 

*  Ries  and  Leighton's  History  of  the  Clay-working  Industry  of  the  United 

States 8vo.  2  50 

Sabin's  Industrial  and  Artistic  Technology  of  Paint  and  Varnish 8vo,  3  00 

*  Smith's  Strength  of  Material 12mo  1  25 

Snow's  Principal  Species  of  Wood 8vo,  3  50 

Spalding's  Hydraulic  Cement 12mo,  2  00 

Text-book  on  Roads  and  Pavements 12mo,  2  00 

*  Taylor  and  Thompson's  Extracts  on  Reinforced  Concrete  Design 8vo,  2  00 

Treatise  on  Concrete,  Plain  and  Reinforced 8vo,  5  00 

Thurston's  Materials  of  Engineering.     In  Three  Parts 8vo,  8  00 

Part  I.     Non-metallic  Materials  of  Engineering  and  Metallurgy. .  .  .  8vo,  2  00 

Part  II.     Iron  and  Steel 8vo,  3  50 

Part  III.    A  Treatise  on  Brasses,  Bronzes,  and  Other  Alloys  and  their 

Constituents 8vo,  2  50 

Tillson's  Street  Pavements  and  Paving  Materials 8vo,  4  00 

*  Trautwine's  Concrete,  Plain  and  Reinforced 16mo,  2  00 

Turneaure  and  Maurer's  Principles  of  Reinforced  Concrete  Construction. 

Second  Edition,  Revised  and  Enlarged 8vo,  3  50 

Waterbury's  Cement  Laboratory  Manual 12mo,  1  00 

Wood's  (De  V.)  Treatise  on  the  Resistance  of  Materials,  and  an  Appendix  on 

the  Preservation  of  Timber 8vo,  2  00 

Wood's  (M.  P.)  Rustless  Coatings:  Corrosion  and  Electrolysis  of  Iron  and 

Steel 8vo,  4  00 


RAILWAY   ENGINEERING. 

Andrews's  Handbook  for  Street  Railway  Engineers 3X5  inches,  mor.  1  25 

Berg's  Buildings  and  Structures  of  American  Railroads 4to,  5  00 

Brooks's  Handbook  of  Street  Railroad  Location 16mo,  mor.  1  50 

Butts's  Civil  Engineer's  Field-book 16mo,  mor.  2  50 

Crandall's  Railway  and  Other  Earthwork  Tables 8vo,  1  50 

Crandall  and  Barnes's  Railroad  Surveying 16mo,  mor.  2  00 

*  Crockett's  Methods  for  Earthwork  Computations 8vo,  1   50 

Dredge's  History  of  the  Pennsylvania  Railroad.   (1879) Paper,  5  00 

Fisher's  Table  of  Cubic  Yards. Cardboard,  25 

Godwin's  Railroad  Engineers'  Field-book  and  Explorers'  Guide. .  16mo,  mor.  2  50 
Hudson's  Tables  for  Calculating  the  Cubic  Contents  of  Excavations  and  Em- 
bankments  8vo,  1  00 

Ives  and  Hilts's  Problems  in  Surveying,  Railroad  Surveying  aiiJ  Geodesy 

16mo,  mor.  1  50 

Molitor  and  Beard's  Manual  for  Resident  Engineers 16mo,  1  00 

Nagle's  Field  Manual  for  Railroad  Engineers ....  16mo,  mor.  3  00 

*  Orrock's  Railroad  Structures  and  Estimates 8vo,  3  00 

Philbrick's  Field  Manual  for  Engineers 16mo,  mor.  3  00 

Raymond's  Railroad  Field  Geometry 16mo,  mor.  2  00 

Elements  of  Railroad  Engineering 8vo,  3  50 

Railroad  Engineer's  Field  Book.      (In  Preparation.) 

Roberts'  Track  Formulae  and  Tables 16mo,  mor.  3  00 

9 


Searles's  Field  Engineering IGmo,  mor.  $3  00 

Railroad  Spiral. 16mo,  mor.  1  50 

Taylor's  Prismoidal  Formulae  and  Earthwork 8vo,  1  50 

*  Trautwine's  Field  Practice  of  Laying  Out  Circular  Curves  for  Railroads. 

12mo,  mor.  2  50 

*  Method  of  Calculating  the  Cubic  Contents  of  Excavations  and  Em- 
bankments by  the  Aid  of  Diagrams 8vo,  2  00 

Webb's  Economics  of  Railroad  Construction Large  12mo,  2  50 

Railroad  Construction 16mo,  mor.  5  00 

Wellington's  Economic  Theory  of  the  Location  of  Railways Large  12mo,  5  00 

Wilson's  Elements  of  Railroad-Track  and  Construction 12mo,  2  00 


DRAWING. 

K 

Barr's  Kinematics  of  Machinery 8vo,  2  50 

*  Bartlett's  Mechanical  Drawing 8vo,  3  00 

*  "                                                      Abridged  Ed 8vo,  150 

*  Bartlett  and  Johnson's  Engineering  Descriptive  Geometry 8vo,  1  50 

Coolidge's  Manual  of  Drawing 8vo,  paper,  1  00 

Coolidge  and  Freeman's  Elements  of  General  Drafting  for  Mechanical  Engi- 
neers  Oblong  4to.  2  50 

Durley's  Kinematics  of  Machines 8vo,  4  00 

Emch's  Introduction  to  Projective  Geometry  and  its  Application 8vo,  2  50 

Hill's  Text-book  on  Shades  and  Shadows,  and  Perspective 8vo,  2  00 

Jamison's  Advanced  Mechanical  Drawing 8vo,  2  00 

Elements  of  Mechanical  Drawing 8vo,  2  50 

Jones's  Machine  Design: 

Part  I.     Kinematics  of  Machinery 8vo,  1  50 

Part  II.  Form,  Strength,  and  Proportions  of  Parts 8vo,  3  00 

Kaup's  Text-book  on  Machine  Shop  Practice.     (In  Press.) 

*  Kimball  and  Barr's  Machine  Design 8vo,  3  00 

MacCord's  Elements  of  Descriptive  Geometry 8vo,  3  00 

Kinematics;  or,  Practical  Mechanism 8vo,  5  00 

Mechanical  Drawing 4to,  4  00 

Velocity  Diagrams 8vo,  1  50 

McLeod's  Descriptive  Geometry Large  12mo,  1  50 

*  Mahan's  Descriptive  Geometry  and  Stone-cutting 8vo,  1  50 

Industrial  Drawing.      (Thompson.) 8vo,  3  50 

Moyer's  Descriptive  Geometry 8vo,  2  00 

Reed's  Topographical  Drawing  and  Sketching 4to,  5  00 

*  Reid's  Mechanical  Drawing.      (Elementary  and  Advanced.) 8vo,  2  00 

Text-book  of  Mechanical  Drawing  and  Elementary  Machine  Design.. 8vo,  3  00 

Robinson's  Principles  of  Mechanism 8vo,  3  00 

Schwamb  and  Merrill's  Elements  of  Mechanism 8vo,  3  00 

Smith  (A.  W.)  and  Marx's  Machine  Design Svo,  3  00 

Smith's  (R.  S.)  Manual  of  Topographical  Drawing.     (McMillan.) Svo,  2  50 

*  Titsworth's  Elements  of  Mechanical  Drawing Oblong  Svo,  1  25 

Warren's  Drafting  Instruments  and  Operations 12mo,  1  25 

Elements  of  Descriptive  Geometry,  Shadows,  and  Perspective 8vo,  3  50 

Elements  of  Machine  Construction  and  Drawing Svo,  7  50 

Elements  of  Plane  and  Solid  Free-hand  Geometrical  Drawing.  . .  .  12mo,  1  00 

General  Problems  of  Shades  and  Shadows Svo,  3  00 

Manual  of  Elementary  Problems  in  the  Linear  Perspective  of  Forms  and 

Shadow 12mo,  1  00 

Manual  of  Elementary  Projection  Drawing 12mo,  1  50 

Plane  Problems  in  Elementary  Geometry 12mo,  1  25 

Weisbach's     Kinematics    and    Power    of    Transmission.      (Hermann    and 

Klein.) Svo,  5  00 

Wilson's  (H.  M.)  Topographic  Surveying Svo,  3  50 

*  Wilson's  (V.  T.)  Descriptive  Geometry Svo,  1  50 

Free-hand  Lettering Svo,  1  00 

Free-hand  Perspective Svo,  2  50 

Woolf's  Elementary  Course  in  Descriptive  Geometry Large  Svo,  3  00 

10 


ELECTRICITY   AND    PHYSICS. 

*  Abegg's  Theory  of  Electrolytic  Dissociation,     (von  Ende.!) 12mo,  $1  25 

Andrews's  Hand-book  for  Street  Railway  Engineering 3X5  inches,  mor.  1  25 

Anthony  and   Ball's  Lecture-notes  on  the  Theory  of  Electrical   Measure- 
ments  12mo,  1  00 

Anthony  and   Brackett's  Text-book  of  Physics.     (Magie.) ...  .Large  12mo,  3  00 

Benjamin's  History  of  Electricity 8vo,  3  00 

Betts's  Lead  Refining  and  Electrolysis 8vo,  4  00 

Classen's  Quantitative  Chemical  Analysis  by  Electrolysis.      (Boltwood.).Svo,  '  3  00 

*  Collins's  Manual  of  Wireless  Telegraphy  and  Telephony 12mo,  1  50 

Crehore  and  Squier's  Polarizing  Photo-chronograph 8vo,  3  00 

*  Danneel's  Electrochemistry.     (Merriam.) 12mo,  1  25 

Dawson's  "Engineering"  and  Electric  Traction  Pocket-book.  .  .  .  16mo,  mor.  5  00 
Dolezalek's  Theory  of  the  Lead  Accumulator  (Storage  Battery),      (von  Ende.) 

12mo,  2  50 

Duhem's  Thermodynamics  and  Chemistry.     (Burgess.) 8vo,  4  00 

Flather's  Dynamometers,  and  the  Measurement  of  Power 12mo,  3  00 

*  Getman's  Introduction  to  Physical  Science 12mo,  1  50 

Gilbert's  De  Magnete.      (Mottelay  ) 8vo,  2  50 

*  Hanchett's  Alternating  Currents 12mo,  1  00 

Hering's  Ready  Reference  Tables  (Conversion  Factors) 16mo,  mor.  2  50 

*  Hobart  and  Ellis's  High-speed  Dynamo  Electric  Machinery 8vo,  6  00 

Holman's  Precision  of  Measurements 8vo,  2  00 

Telescopic  Mirror-scale  Method,  Adjustments,  and  Tests..  .  .Large  8vo,  75 
Hutchinson's  High  Efficiency  Electrical  Illuminants  and  Illumination.  (In  Press.) 
Karapetoff' s  Experimental  Electrical  Engineering: 

*  Vol.    1 8vo,  3  50 

*  Vol.  II 8vo,  2  50 

Kinzbrunner's  Testing  of  Continuous-current  Machines .8vo,  2  OO1 

Landauer's  Spectrum  Analysis.     (Tingle.) 8vo,  3  00 

Le  Chatelier's  High-temperature  Measurements.      (Boudouard — Burgess.) 

12mo,  3  00 

Lob's  Electrochemistry  of  Organic  Compounds.      (Lorenz.) 8vo,  3  00 

*  Lyndon's  Development  and  Electrical  Distribution  of  Water  Power.  .8vo,  3  00 

*  Lyons's  Treatise  on  Electromagnetic  Phenomena.  Vols,  I  .and  II.  8vo,  each,  6  00 

*  Michie's  Elements  of  Wave  Motion  Relating  to  Sound  and  Light 8vo,  4  OO 

Morgan's  Outline  of  the  Theory  of  Solution  and  its  Results 12mo,  1  00 

*  Physical  Chemistry  for  Electrical  Engineers 12mo,  1,  50 

*  Norris's  Introduction  to  the  Study  of  Electrical  Engineering 8vo,  2  50 

Norris  and  Dennison's  Course  of  Problems  on  the  Electrical  Characteristics  of 

Circuits  and  Machines.      (In  Press.) 

*  Parshall  and  Hobart's  Electric  Machine  Design 4to,  half  mor,  12  50 

Reagan's  Locomotives:  Simple,  Compound,  and  Electric.     New  Edition. 

Large  12mo,  3  50 

*  Rosenberg's  Electrical  Engineering.     (Haldane  Gee — Kinzbrunner.) .  .8vo,  2  00 

Ryan,  Norris,  and  Hoxie's  Electrical  Machinery.     Vol.  1 8vo,  2  50 

Schapper's  Laboratory  Guide  for  Students  in  Physical  Chemistry 12mo,  1  00 

*  Tillman's  Elementary  Lessons  in  Heat 8vo,  1  50 

*  Timbie's  Elements  of  Electricity Large  12mo,  2  00 

Tory  and  Pitcher's  Manual  of  Laboratory  Physics Large  12mo,  2  00 

Ulke's  Modern  Electrolytic  Copper  Refining 8vo,  3  00 


LAW. 

*  Brennan's   Hand-book  of  Useful  Legal   Information   for  Business   Men. 

16mo,  mor.  5  00 

*  Davis's  Elements  of  Law 8vo,  2  50 

*  Treatise  on  the  Military  Law  of  United  States 8vo,  7  00 

*  Dudley's  Military  Law  and  the  Procedure  of  Courts-martial. .  Large  12mo,  2  50 

Manual  for  Courts-martial 16mo,  mor.  1  50 

Wait's  Engineering  and  Architectural  Jurisprudence 8vo,  6  00 

Sheep,  6  50 

11 


Wait's  Law  of  Contracts 8vo,  $3  00 

Law  of  Operations  Preliminary  to    Construction  in  Engineering  and 

Architecture 8vo,     5  00 

Sheep,     5  50 
Baker's  Elliptic  Functions 8vo,      1  50 


MATHEMATICS. 


Briggs  s  Elements  of  Plane  Analytic  Geometry.     (B6cher.) 12mo,  1  00 

*  Buchanan's  Plane  and  Spherical  Trigonometry 8vo,  1  00 

Byerly's  Harmonic  Functions 8vo,  1  00 

Chandler's  Elements  of  the  Infinitesimal  Calculus 12mo,  2  00 

*  Coffin's  Vector  Analysis 12mo,  2  50 

Compton's  Manual  of  Logarithmic  Computations 12mo,  1   50 

*  Dickson's  College  Algebra Large  12mo,  1  50 

*  Introduction  to  the  Theory  of  Algebraic  Equations Large  12mo,  1  25 

Emch's  Introduction  to  Projective  Geometry  and  its  Application 8vo,  2  50 

Fiske's  Functions  of  a  Complex  Variable 8vo,  1  00 

Ha,lsted's  Elementary  Synthetic  Geometry 8vo,  1  50 

Elements  of  Geometry 8vo,  1  75 

*  Rational  Geometry 12mo,  1  50 

Synthetic  Projective  Geometry 8vo,  1  00 

*  Hancock's  Lectures  on  the  Theory  of  Elliptic  Functions 8vo,  5  00 

Hyde's  Grassmann's  Space  Analysis 8vo,  1  00 

*  Johnson's  (J.  B.)  Three-place  Logarithmic  Tables:  Vest-pocket  size,  paper,  15 

*  100  copies,  5  00 

*  Mounted  on  heavy  cardboard,  8  X 10  inches,  25 

*  10  copies,  2  00 
Johnson's  (W.  W.)  Abridged  Editions  of  Differential  and  Integral  Calculus. 

Large  12mo,  1  vol.  2  50 

Curve  Tracing  in  Cartesian  Co-ordinates 12mo,  „  1  00 

Differential  Equations 8vo,  1  00 

Elementary  Treatise  on  Differential  Calculus Large  12mo,  1  60 

Elementary  Treatise  on  the  Integral  Calculus Large  12mo,  1  50 

*  Theoretical  Mechanics 12mo,  3  00 

Theory  of  Errors  and  the  Method  of  Least  Squares 12mo,  1  50 

Treatise  on  Differential  Calculus Large  12mo,  3  00 

Treatise  on  the  Integral  Calculus Large  12mo,  3  00 

Treatise  on  Ordinary  and  Partial  Differential  Equations.  .  .Large  12mo,  3  50 

Karapetoff's  Engineering  Applications  of  Higher  Mathematics.      (In  Preparation.) 

Laplace's  Philosophical  Essay  on  Probabilities.  (Truscott  and  Emory.) .  12mo,  2  00 

*  Ludlow's  Logarithmic  and  Trigonometric  Tables 8vo,  1  00 

*  Ludlow  and  Bass's  Elements  of  Trigonometry  and  Logarithmic  and  Other 

Tables 8vo.  3  00 

*  Trigonometry  and  Tables  published  separately Each,  2  00 

Macfarlane's  Vector  Analysis  and  Quaternions 8vo,  1  00 

McMahon's  Hyperbolic  Functions 8vo,  1  00 

Manning's  Irrational  Numbers  and  their  Representation  by  Sequences  and 

Series 12mo,  1  25 

Mathematical   Monographs.     Edited  by   Mansfield   Merriman   and    Robert 

S.  Woodward Octavo,  each  1  00 

No.  1.  History  of  Modern  Mathematics,  by  David  Eugene  Smith. 
No.  2.  Synthetic  Projective  Geometry,  by  George  Bruce  Halsted. 
No.  3.  Determinants,  by  Laenas  Gifford  Weld.  No.  4.  Hyper- 
bolic Functions,  by  James  McMahon.  No.  5.  Harmonic  Func- 
tions, by  William  E.  Byerly.  No.  6.  Grassmann's  Space  Analysis, 
by  Edward  W.  Hyde.  No.  7.  Probability  and  Theory  of  Errors, 
by  Robert  S.  Woodward.  No.  8.  Vector  Analysis  and  Quaternions, 
by  Alexander  Macfarlane.  No.  9.  Differential  Equations,  by 
William  Woolsey  Johnson.  No.  10.  The  Solution  of  Equations, 
by  Mansfield  Merriman.  No.  11.  Functions  of  a  Complex  Variable, 
by  Thomas  S.  Fiske. 

Maurer's  Technical  Mechanics 8vo,  4  00 

Merriman's  Method  of  Least  Squares 8vo,  2  00 

Solution  of  Equations 8vo.  1  00 

12 


Moritz's  Elements  of  Plane  Trigonometry.     (In  Press.) 

Rice  and  Johnson's  Differential  and  Integral  Calculus.     2  vols.  in  one. 

Large  12mo,  $1  50 

Elementary  Treatise  on  the  Differential  Calculus Large  12mo,  3  00 

Smith's  History  of  Modern  Mathematics 8vo,  1  00 

*  Veblen  and  Lennes's  Introduction  to  the  Real  Infinitesimal  Analysis  of  One 

Variable 8vo,  2  00 

*  Waterbury's  Vest  Pocket  Hand-book  of  Mathematics  for  Engineers. 

2$X5f  inches,  rnor.  1  00 

*  Enlarged  Edition,  Including  Tables mor.  1  50 

Weld's  Determinants 8vo,  1  00 

Wood's  Elements  of  Co-ordinate  Geometry 8vo,  2  00 

Woodward's  Probability  and  Theory  of  Errors 8vo,  1  00 


MECHANICAL  ENGINEERING. 

MATERIALS  OP  ENGINEERING.  STEAM-ENGINES   AND   BOILERS. 

Bacon's  Forge  Practice 12mo,  1  50 

Baldwin's  Steam  Heating  for  Buildings 12mo,  2  50 

Barr's  Kinematics  of  Machinery 8vo,  2  50 

*  Bartlett's  Mechanical  Drawing 8vo,  3  00 

*  "  Abridged  Ed 8vo,  1  50 

*  Bartlett  and  Johnson's  Engineering  Descriptive  Geometry 8vo,  1  50 

*  Burr's  Ancient  and  Modern  Engineering  and  the  Isthmian  Canal 8vo,  3  50 

Carpenter's  Experimental  Engineering 8vo,  6  00 

Heating  and  Ventilating  Buildings 8vo,  4  00 

*  Clerk's  The  Gas,  Petrol  and  Oil  Engine 8vo,  4  00 

Compton's  First  Lessons  in  Metal  Working 12mo,  1  50 

Compton  and  De  Groodt's  Speed  Lathe 12mo,  1  50 

Coolidge's  Manual  of  Drawing 8vo,  paper,  1  00 

Coolidge  and  Freeman's  Elements  of  General  Drafting  for  Mechanical  En- 
gineers  Oblong  4to,  2  50 

Cromwell's  Treatise  on  Belts  and  Pulleys 12mo,  1  50 

Treatise  on  Toothed  Gearing 12mo,  1  50 

Dingey's  Machinery  Pattern  Making 12mo,  2  00 

Durley 's  Kinematics  of  Machines 8vo,  4  00 

Flanders's  Gear-cutting  Machinery Large  12mo,  3  00 

Flather's  Dynamometers  and  the  Measurement  of  Power 12mo,  3  00 

•     Rope  Driving 12mo,  2  00 

•Gill's  Gas  and  Fuel  Analysis  for  Engineers 12mo,  1  25 

Goss's  Locomotive  Sparks '. 8vo,  2  00 

•Greene's  Pumping  Machinery.     (In  Preparation.) 

Hering's  Ready  Reference  Tables  (Conversion  Factors) 16mo,  mor.  2  50 

*  Hobart  and  Ellis's  High  Speed  Dynamo  Electric  Machinery. 8vo,  6  00 

Hutton's  Gas  Engine 8vo,  5  00 

Jamison's  Advanced  Mechanical  Drawing 8vo,  2  00 

Elements  of  Mechanical  Drawing 8vo,  2  50 

Jones's  Gas  Engine 8vo,  4  00 

Machine  Design: 

Part  I.     Kinematics  of  Machinery '. 8vo,  1  50 

Part  II.  Form,  Strength,  and  Proportions  of  Parts 8vo,  3  00 

Kaup's  Text-book  on  Machine  Shop  Practice.  (In  Press.) 

*  Kent's  Mechanical  Engineer's  Pocket-Book 16mo,  mor.  5  00 

Kerr's  Power  and  Power  Transmission 8vo,  2  00 

•*  Kimball  and  Barr's  Machine  Design 8vo,  3  00 

Leonard's  Machine  Shop  Tools  and  Methods 8vo,  4  00 

*  Levin's  Gas  Engine 8vo,  4  00 

*  Lorenz's  Modern  Refrigerating  Machinery.   (Pope,  Haven,  and  Dean).  .8vo,  4  00 
MacCord's  Kinematics;  or,  Practical  Mechanism 8vo,  5  00 

Mechanical  Drawing 4to,  4  00 

Velocity  Diagrams 8vo,  1  50 

MacFarland's  Standard  Reduction  Factors  for  Gases 8vo,  1  50 

.Mahan's  Industrial  Drawing.     (Thompson.) 8vo,  3  50 

13 


Mehrtens's  Gas  Engine  Theory  and  Design Large  12mo,  $2  50 

Oberg's  Handbook  of  Small  Tools Large  12mo,  2  50 

*  Parshall  and  Hobart's  Electric  Machine  Design.  Small  4to,  half  leather,  12  50 

*  Peele's  Compressed  Air  Plant  for  Mines.     Second  Edition,  Revised  and  En- 

larged   8vo,  3  50 

Poole's  Calorific  Power  of  Fuels 8vo,  3  00 

*  Porter's  Engineering  Reminiscences,  1855  to  1882 8vo,  3  00 

*  Reid's  Mechanical  Drawing.     (Elementary  and  Advanced.) 8vo,  2  00 

Text-book  of  Mechanical  Drawing  and  Elementary  Machine  Design. 8vo,  3  00 

Richards's  Compressed  Air 12mo,  1  50 

Robinson's  Principles  of  Mechanism vj 8vo,  3  00 

Schwamb  and  Merrill's  Elements  of  Mechanism 8vo,  3  00 

Smith  (A.  W.)  and  Marx's  Machine  Design 8vo,  3  00 

Smith's  (O.)  Press-working  of  Metals 8vo,  3  00 

Sorel's  Carbureting  and  Combustion  in  Alcohol  Engines.     (Woodward  and 

Preston.) Large  12mo,  3  00 

Stone's  Practical  Testing  of  Gas  and  Gas  Meters *.- 8vo,  3  50 

Thurston's  Animal  as  a  Machine  and  Prime  Motor,  and  the  Laws  of  Energetics. 

12mo,  1  00 

Treatise  on  Friction  and  Lost  Work  in  Machinery  and  Mill  Work.  .  .8vo,  3  00 

*  Tillson's  Complete  Automobile  Instructor 16mo,  1  50 

*  Titsworth's  Elements  of  Mechanical  Drawing Oblong  8vo,  1  25 

Warren's  Elements  of  Machine  Construction  and  Drawing 8vo,  7  50 

*  Waterbury's  Vest  Pocket  Hand-book  of  Mathematics  for  Engineers. 

2JX5|  inches,  mor.  100 

*  Enlarged  Edition,  Including  Tables mor.  1  50 

Weisbach's    Kinematics   and    the    Power   of   Transmission.      (Herrmann — 

Klein.) 8vo,  5  00 

Machinery  of  Transmission  and  Governors.     (Hermann — Klein.).  .8vo,  500 

Wood's  Turbines 8vo,  2  50 


MATERIALS   OF  ENGINEERING. 

*  Bovey's  Strength  of  Materials  and  Theory  of  Structures 8vo,  7  50 

Burr's  Elasticity  and  Resistance  of  the  Materials  of  Engineering 8vo,  7  50 

Church's  Mechanics  of  Engineering 8vo,  6  00 

*  Greene's  Structural  Mechanics 8vo,  2  50 

*  Holley's  Lead  and  Zinc  Pigments Large  12mo  3  00 

Holley  and  Ladd's  Analysis  of  Mixed  Paints,  Color  Pigments,  and  Varnishes. 

Large  12mo,  2  50 
Johnson's  (C.  M.)  Rapid    Methods   for    the   Chemical    Analysis    of    Special 

Steels,  Steel-Making  Alloys  and  Graphite Large  12mo,  3  00 

Johnson's  (J.  B.)  Materials  of  Construction 8vo,  6  00 

Keep's  Cast  Iron 8vo,  2  50 

Lanza's  Applied  Mechanics 8vo,  7  50 

Lowe's  Paints  for  Steel  Structures 12mo,  1  00 

Maire's  Modern  Pigments  and  their  Vehicles 12mo,  2  00 

Maurer's  Technical  Mechanics - 8vo,  4  00 

Merriman's  Mechanics  of  Materials 8vo,  5  00' 

*  Strength  of  Materials 12mo,  1  00 

Metcalf 's  Steel.     A  Manual  for  Steel-users 12mo,  2  00 

Sabin's  Industrial  and  Artistic  Technology  of  Paint  and  Varnish 8vo,  3  00 

Smith's  ((A.  W.)  Materials  of  Machines 12mo,  1  00 

*  Smith's  (H.  E.)  Strength  of  Material 12mo,  1  25 

Thurston's  Materials  of  Engineering 3  vols.,  8vo,  8  00 

Part  I.     Non-metallic  Materials  of  Engineering 8vo,  2  00 

Part  II.     Iron  and  Steel 8vo,  3  50 

Part  III.     A  Treatise  on  Brasses,  Bronzes,  and  Other  Alloys  and  their 

Constituents 8vo,  2  50 

Wood's  (De  V.)  Elements  of  Analytical  Mechanics 8vo.  3  00 

Treatise  on    the    Resistance    of    Materials    and    an    Appendix   on    the 

Preservation  of  Timber 8vo,  2  00- 

Wood's  (M.  P.)  Rustless  Coatings:    Corrosion  and  Electrolysis  of  Iron  and 

Steel 8vo,  4  00 

14 


STEAM-ENGINES    AND    BOILERS. 

Berry's  Temperature-entropy  Diagram 12mo,  $2  00 

Carnot's  Reflections  on  the  Motive  Power  of  Heat.     (Thurston.) 12mo,  1  50 

Chase's  Art  of  Pattern  Making 12mo,  2  50 

Creighton's  Steam-engine  and  other  Heat  Motors 8vo,  5  00 

Dawson's  "Engineering"  and  Electric  Traction  Pocket-book.  ..  .  Idmo,  mor.  5  00 

*  Gebhardt's  Steam  Power  Plant  Engineering 8vo,  6  00 

Goss's  Locomotive  Performance 8vo,  5  00 

Hemenway's  Indicator  Practice  and  Steam-engine  Economy 12mo,  2  00 

Hutton's  Heat  and  Heat-engines 8vo,  5  00 

Mechanical  Engineering  of  Power  Plants 8vo,  5  00 

Kent's  Steam  Boiler  Economy 8vo,  4  00 

Kneass's  Practice  and  Theory  of  the  Injector 8vo,  1  50 

MacCord's  Slide-valves .8vo,  2  00 

Meyer's  Modern  Locomotive  Construction 4to,  10  00 

Moyer's  Steam  Turbine 8vo,  4  00 

Peabody's  Manual  of  the  Steam-engine  Indicator 12mo,  1  50 

Tables  of  the  Properties  of  Steam  and  Other  Vapors  and  Temperature- 
Entropy  Table .8vo,  1  00 

Thermodynamics  of  the  Steam-engine  and  Other  Heat-engines.  .  .  .8vo,  5  00 

Valve-gears  for  Steam-engines 8vo,  2  50 

Peabody  and  Miller's  Steam-boilers 8vo,  4  00 

Pupin's  Thermodynamics  of  Reversible  Cycles  in  Gases  and  Saturated  Vapors. 

(Osterberg.) 12mo,  1  25 

Reagan's  Locomotives:  Simple,  Compound,  and  Electric.     New  Edition. 

Large  12mo,  3  50 

Sinclair's  Locomotive  Engine  Running  and  Management 12mo,  2  00 

Smart's  Handbook  of  Engineering  Laboratory  Practice .-  •  •  •  12mo,  2  50 

Snow's  Steam-boiler  Practice 8vo,  3  00 

Spangler's  Notes  on  Thermodynamics 12mo,  1  00 

Valve-gears 8vo,  2  50 

Spangler,  Greene,  and  Marshall's  Elements  of  Steam-engineering 8vo,  3  00 

Thomas's  Steam-turbines 8vo,  4  00 

Thurston's  Handbook  of  Engine  and  Boiler  Trials,  and  the  Use  of  the  Indi- 
cator and  the  Prony  Brake 8vo,  5  00. 

Handy  Tables : .  .8vo,  1  50 

Manual  of  Steam-boilers,  their  Designs,  Construction,  and  Operation  8vo,  5  00 

Manual  of  the  Steam-engine 2  vols.,  8vo,  10  00 

Part  I.     History,  Structure,  and  Theory 8vo,  6  00 

Part  II.     Design,  Construction,  and  Operation 8vo,  6  00 

Wehrenfennig's  Analysis  and  Softening  of  Boiler  Feed-water.     (Patterson.) 

8vo,  4  00 

Weisbach's  Heat,  Steam,  and  Steam-engines.     (Du  Bois.) 8vo,  5  00 

Whitham's  Steam-engine  Design 8vo,  5  00 

Wood's  Thermodynamics,  Heat  Motors,  and  Refrigerating  Machines.  .  .8vo,  4  00 


MECHANICS   PURE   AND    APPLIED. 

Church's  Mechanics  of  Engineering 8vo,  6  00 

*  Mechanics  of  Internal  Works 8vo,  1  50 

Notes  and  Examples  in  Mechanics 8vo,  2  00 

Dana's  Text-book  of  Elementary  Mechanics  for  Colleges  and  Schools  .12mo,  1  50 
Du  Bois's  Elementary  Principles  of  Mechanics: 

Vol.    I.     Kinematics 8vo,  3  50 

Vol.  II.     Statics 8vo.  4  00 

Mechanics  of  Engineering.     Vol.    I Small  4to,  7  50 

Vol.  II Small  4to,  10  00 

*  Greene's  Structural  Mechanics 8vo,  2  50 

*  Hartmann's  Elementary  Mechanics  for  Engineering  Students 12mo,  1  25 

James's  Kinematics  of  a  Point  and  the  Rational  Mechanics  of  a  Particle. 

Large  12mo.  2  00 

*  Johnson's  (W.  W.)  Theoretical  Mechanics 12mo,  3  00 

Lanza's  Applied  Mechanics 8vo,  7  50 

15 


*  Martin's  Text  Book  on  Mechanics,  Vol.  I,  Statics 12mo,  $1  25 

*  Vol.  II,  Kinematics  and  Kinetics.  12mo,  1   50 

Maurer's  Technical  Mechanics 8vo.  4  00 

*  Merriman's  Elements  of  Mechanics 12mo,  1  00 

Mechanics  of  Materials 8vo,  5  00 

*  Michie's  Elements  of  Analytical  Mechanics 8vo,  4  00 

Robinson's  Principles  of  Mechanism 8vo,  3  00 

Sanborn's  Mechanics  Problems Large  12mo,  1  50 

Schwamb  and  Merrill's  Elements  of  Mechanism 8vo,  3  00 

Wood's  Elements  of  Analytical  Mechanics. 8vo,  3  00 

Principles  of  Elementary  Mechanics 12mo,  1  25 

'    .  ** 

MEDICAL. 

*  Abderhalden's  Physiological   Chemistry   in   Thirty   Lectures.     (Hall   and 

Defren.) *. 8vo,  5  00 

von  Behring's  Suppression  of  Tuberculosis.     (Bolduan.) 12mo,  1  00 

Bolduan's  Immune  Sera ." 12mo,  1  50 

Bordet's  Studies  in  Immunity.     (Gay.) 8vo,  6  00 

*  Chapin's  The  Sources  and  Modes  of  Infection Large  12mo,  3  00 

Davenport's  Statistical  Methods  with  Special  Reference  to  Biological  Varia- 
tions  16mo,  mor.  1  50 

Ehrlich's  Collected  Studies  on  Immunity.     (Bolduan.) 8vo,  6  00 

*  Fischer's  Oedema 8vo,  2  00 

*  Physiology  of  Alimentation .  Large  12mo,  2  00 

de  Fursac's  Manual  of  Psychiatry.     (Rosanoff  and  Collins.) Large  12mo,  2  50 

Hammarsten's  Text-book  on  Physiological  Chemistry.     (Mandel.) 8vo,  4  00 

Jackson's  Directions  for  Laboratory  Work  in  Physiological  Chemistry.  .8vo,  1  25 

Lassar-Cohn's  Praxis  of  Urinary  Analysis.     (Lorenz.) 12mo,  1  00 

Mandel's  Hand-book  for  the  Bio-Chemical  Laboratory 12mo,  1  50 

*  Nelson's  Analysis  of  Drugs  and  Medicines 12mo,  3  00 

*  Pauli's  Physical  Chemistry  in  the  Service  of  Medicine.      (Fischer.)  ..12mo,  1  25 

*  Pozzi-Escot's  Toxins  and  Venoms  and  their  Antibodies.     (Cohn.).  .  12mo,  1  00 

Rostoski's  Serum  Diagnosis.     (Bolduan.) 12mo,  1  00 

Ruddiman's  Incompatibilities  in  Prescriptions 8vo,  2  00 

Whys  in  Pharmacy 12mo,  1  00 

Salkowski's  Physiological  and  Pathological  Chemistry.     (Orndorff.)  ..  ..8vo,  2  50 

*  Satterlee's  Outlines  of  Human  Embryology 12mo,  1  25 

Smith's  Lecture  Notes  on  Chemistry  for  Dental  Students 8vo,  2  50 

*  Whipple's  Tyhpoid  Fever Large  12mo,  3  00 

*  Woodhull's  Military  Hygiene  for  Officers  of  the  Line Large  12mo,  1  50 

*  Personal  Hygiene 12mo,  1  00 

Worcester  and  Atkinson's  Small  Hospitals  Establishment  and  Maintenance, 

and  Suggestions  for  Hospital  Architecture,  with  Plans  for  a  Small 

Hospital 12mo,  1  25 

METALLURGY. 

Betts's  Lead  Refining  by  Electrolysis 8vo,  4  00 

Bolland's  Encyclopedia  of  Founding  and  Dictionary  of  Foundry  Terms  used 

in  the  Practice  of  Moulding 12mo,  3  00 

Iron  Founder 12mo,  2  50 

Supplement 12mo,  2  50 

Borchers's  Metallurgy.      (Hall  and  Hayward.)      (In  Press.) 

Douglas's  Untechnical  Addresses  on  Technical  Subjects 12mo,  1  00 

Goesel's  Minerals  and  Metals:  A  Reference  Book 16mo,  mor.  3  00 

*  Iles's  Lead-smelting 12mo,  2  50 

Johnson's    Rapid    Methods   for   the  Chemical   Analysis   of   Special   Steels, 

Steel-making  Alloys  and  Graphite Large  12mo,  3  00 

Keep's  Cast  Iron 8vo,  2  50 

Le  Chatelier's  High- temperature  Measurements.     (Boudouard — Burgess.) 

12mo,  3  00 

Metcalf's  Steel.     A  Manual  for  Steel-users 12mo,  2  00 

Minet's  Production  of  Aluminum  and  its  Industrial  Use.      (Waldo.).  .  12mo,  2  50 

*  Ruer's  Elements  of  Metallography.     (Mathewson.) 8vo,  3  00 

16 


Smith's  Materials  of  Machines 12mo,  $1  00 

Tate  and  Stone's  Foundry  Practice 12mo,  2  00 

Thurston's  Materials  of  Engineering.      In  Three  Parts 8vo,  8  00 

Part  I.      Non-metallic  Materials  of  Engineering,  see  Civil  Engineering, 
page  9. 

Part  II.    Iron  and  Steel 8vo,  3  50 

Part  III.  A  Treatise  on  Brasses,  Bronzes,  and  Other  Alloys  and  their 

Constituents 8vo,  2  50 

Ulke's  Modern  Electrolytic  Copper  Refining 8vo,  3  00 

West's  American  Foundry  Practice 12mo,  2  50 

Moulders'  Text  Book 12mo.  2  50 

MINERALOGY. 

Baskerville's  Chemical  Elements.      (In  Preparation.) 

*  Browning's  Introduction  to  the  Rarer  Elements 8vo,  1  50 

Brush's  Manual  of  Determinative  Mineralogy.     (Penfield.) 8vo,  4  00 

Butler's  Pocket  Hand-book  of  Minerals 16mo,  mor.  3  00 

Chester's  Catalogue  of  Minerals 8vo,  paper,  1  00 

Cloth,  1  25 

*  Crane's  Gold  and  Silver 8vo,  5  00 

Dana's  First  Appendix  to  Dana's  New  "System  of  Mineralogy".  .Large  8vo,  1  00 
Dana's  Second  Appendix  to  Dana's  New  "  System  of  Mineralogy." 

Large  8vo,  1  50 

Manual  of  Mineralogy  and  Petrography 12mo,  2  00 

Minerals  and  How  to  Study  Them 12mo,  1  50 

System  of  Mineralogy Large  8vo,  half  leathor,  12  50 

Text-book  of  Mineralogy 8vo,  4  00 

Douglas's  Untechnical  Addresses  on  Technical  Subjects 12mo,  1  00 

Eakle's  Mineral  Tables 8vo,  1  25 

Eckel's  Stone  and  Clay  Products  Used  in  Engineering.     (In  Preparation.) 

Goesel's  Minerals  and  Metals:  A  Reference  Book 16mo,  mor.  3  00 

Groth's  The  Optical  Properties  of  Crystals.     (Jackson.)      (In  Press.) 

Groth's  Introduction  to  Chemical  Crystallography  (Marshall) 12mo,  1  25 

*  Hayes's  Handbook  for  Field  Geologists 16mo,  mor.  1  50 

Iddings's  Igneous  Rocks 8vo,  5  00 

Rock  Minerals 8vo,  5  00 

Johannsen's  Determination  of  Rock-forming  Minerals  in  Thin  Sections.  8vo, 

With  Thumb  Index  5  00 

*  Martin's  Laboratory    Guide    to    Qualitative    Analysis    with    the    Blow- 

Pipe 12mo,  60 

Merrill's  Non-metallic  Minerals:  Their  Occurrence  and  Uses 8vo,  4  00 

Stones  for  Building  and  Decoration 8vo,  5  00 

*  Penfield's  Notes  on  Determinative  Mineralogy  and  Record  of  Mineral  Tests. 

8vo,  paper,  50 
Tables  of  Minerals,   Including  the  Use  of  Minerals  and  Statistics  of 

Domestic  Production.  . 8vo,  1  00 

*  Pirsson's  Rocks  and  Rock  Minerals 12mo,  2  50 

*  Richards's  Synopsis  of  Mineral  Characters 12mo,  mor.  1  25 

*  Ries's  Clays:  Their  Occurrence,  Properties  and  Uses 8vo,  5  00 

*  Ries  and  Leighton's  History  of  the  Clay-working  Industry  of  the  United 

States 8vo,  2  50 

Rowe's  Practical  Mineralogy  Simplified.     (In  Press.) 

*  Tillman's  Text-book  of  Important  Minerals  and  Rocks 8vo,  2  00 

Washington's  Manual  of  the  Chemical  Analysis  of  Rocks 8vo,  2  00 

MINING. 

*  Beard's  Mine  Gases  and  Explosions Large  12mo,  3  00 

*  Crane's  Gold  and  Silver 8vo,  5  00 

*  Index  of  Mining  Engineering  Literature 8vo,  4  00 

*  8vo,  mor.  5  00 

*  Ore  Mining  Methods 8vo.  3  00 

Douglas's  Untechnical  Addresses  on  Technical  Subjects 12mo,  1  00 

Eissler's  Modern  High  Explosives 8vo,  4  00 

17 


Goesel's  Minerals  arid  Metals:  A  Reference  Book 16mo,  mor.  $3  00 

Ihlseng's  Manual  of  Mining 8vo,  5  00 

*  Iles's  Lead  Smelting 12mo,  2  00 

Peele's  Compressed  Air  Plant  for  Mines 8vo,  3  00 

Riemer's  Shaft  Sinking  Under  Difficult  Conditions.      (Corning  and  Peele.)8vo,  3  00 

*  Weaver's  Military  Explosives 8vo,  3  00 

Wilson's  Hydraulic  and  Placer  Mining.     2d  edition,  rewritten 12mo,  2  50 

Treatise  on  Practical  and  Theoretical  Mine  Ventilation 12mo,  1  25 


SANITARY   SCIENCE. 

Association  of  State  and  National  Food  and  Dairy  Departments,  Hartford 

Meeting,  1906 8vo,  3  00 

Jamestown  Meeting,  1907 8vo,  3  00 

*  Bashore's  Outlines  of  Practical  Sanitation .*....  12mo,  1  25 

Sanitation  of  a  Country  House 12mo,  1  00 

Sanitation  of  Recreation  Camps  and  Parks 12mo,  1  00 

*  Chapin's  The  Sources  and  Modes  of  Infection Large  12mo,  3  00 

Folwell's  Sewerage.      (Designing,  Construction,  and  Maintenance.) 8vo,  3  00 

Water-supply  Engineering 8vo,  4  00 

Fowler's  Sewage  Works  Analyses 12mo,  2  00 

Fuertes's  Water-filtration  Works 12mo,  2  50 

Water  and  Public  Health 12mo,  1  50 

Gerhard's  Guide  to  Sanitary  Inspections 12mo,  1  50 

*  Modern  Baths  and  Bath  Houses 8vo,  3  00 

Sanitation  of  Public  Buildings 12mo,  1  50 

*  The  Water  Supply,  Sewerage,  and  Plumbing  of  Modern  City  Buildings. 

8vo,  4  00. 

Hazen's  Clean  Water  and  How  to  Get  I ' Large  12mo,  1  50 

Filtration  of  Public  Water-supplies 8vo,  3  00 

*  Kinnicutt,  Winslow  and  Pratt's  Sewage  Disposal 8vo,  3  00 

Leach's  Inspection  and  Analysis  of  Food  with  Special  Reference  to  State 

Control 8vo,  7  50 

Mason's  Examination  of  Water.      (Chemical  and  Bacteriological) 12mo,  1  25 

Water-supply.      (Considered  principally  from  a  Sanitary  Standpoint). 

8vo,  4  00 
Mast's  Light  and  the  Behavior  of  Organisms.     (In  Press.) 

*  Merriman's  Elements  of  Sanitary  Engineering 8vo,  2  00 

Ogden's  Sewer  Construction 8vo,  3  00 

Sewer  Design 12mo,  2  00 

Parsons's  Disposal  of  Municipal  Refuse 8vo,  2  00 

Prescott  and  Winslow's  Elements  of  Water  Bacteriology,  with  Special  Refer- 
ence to  Sanitary  Water  Analysis 12md,  1  50 

*  Price's  Handbook  on  Sanitation 12mo,  1  50 

Richards's  Conservation  by  Sanitation.     (In  Press.) 

Cost  of  Cleanness 12mo,  1  00 

Cost  of  Food.     A  Study  in  Dietaries 12mo,  1  00 

Cost  of  Living  as  Modified  by  Sanitary  Science 12mo,  1  00 

Cost  of  Shelter 12mo,  .  1  00 

*  Richards  and  Williams's  Dietary  Computer 8vo,  1  50 

Richards  and  Woodman's  Air,  Water,  and  Food  from  a  Sanitary  Stand- 
point  8vo,  2  00 

*  Richey's     Plumbers',     Steam-fitters',    and     Tinners'     Edition     (Building 

Mechanics'  Ready  Reference  Series) IGmo,  mor.  1  50 

Rideal's  Disinfection  and  the  Preservation  of  Food 8vo,  4  00 

Sewage  and  Bacterial  Purification  of  Sewage 8vo,  4  00 

Soper's  Air  and  Ventilation  of  Subways 12mo,  2  50 

Turneaure  and  Russell's  Public  Water-supplies 8vo,  5  00 

Venable's  Garbage  Crematories  in  America 8vo,  2  00 

Method  and  Devices  for  Bacterial  Treatment  of  Sewage 8vo,  3  00 

Ward  and  Whipple's  Freshwater  Biology.     (In  Press.) 

Whipple's  Microscopy  of  Drinking-water 8vo,  3  50 

*  Typhoid  Fever Large  12mo,  3  00 

Value  of  Pure  Water Large  12mo,  1  00 

Winslow's  Systematic  Relationship  of  the  Coccaceae Large  12mo,  2  50 

18 


MISCELLANEOUS. 

Emmons's  Geological  Guide-book  of  the  Rocky  Mountain  Excursion  of  the 

International  Congress  of  Geologists Large  8vo.  $1   5O 

Ferrel's  Pooular  Treatise  on  the  Winds 8vo,  4  OO 

Fitzgerald's  Boston  Machinist 18mo,  1  OQ 

Gannett's  Statistical  Abstract  of  the  World 24mo,  75 

Haines's  American  Railway  Management 12mo,  2  5O 

Hanausek's  The  Microscopy  of  Technical  Products.     (Winton) 8vo,  5  00 

Jacobs's  Betterment    Briefs.     A   Collection    of    Published    Papers   on    Or- 
ganized Industrial  Efficiency 8vo,  3  50- 

Metcalfe's  Cost  of  Manufactures,  and  the  Administration  of  Workshops.. 8vo,  5  OQ 

Putnam's  Nautical  Charts 8vo,  2  00- 

Ricketts's  History  of  Rensselaer  Polytechnic  Institute  1824-1894. 

Large  12mo,  3  00 

Rotherham's  Emphasised  New  Testament Large  8vo,  2  00 

Rust's  Ex-Meridian  Altitude,  Azimuth  and  Star-finding  Tables 8vo  5  00 

Standage's  Decoration  of  Wood,  Glass,  Metal,  etc ,  .  < 12mo  2  00 

Thome's  Structural  and  Physiological  Botany.      (Bennett) 16mo,  2  25 

Westermaier's  Compendium  of  General  Botany.      (Schneider) 8vo,  2  00' 

Winslow's  Elements  of  Applied  Microscopy 12mo,  1  50"' 


HEBREW   AND   CHALDEE   TEXT-BOOKS. 

Gesenius's  Hebrew  and  Chaldee  Lexicon  to  the  Old  Testament  Scriptures. 

(Tregelles.) Small  4to,  half  mor,     5  00 

Green's  Elementary  Hebrew  Grammar 12mo,     1  25 


19 


UNIVERSITY  OF  CALIFORNIA  LIBRARY 
BERKELEY 


Return  to  desk  from  which  borrowed. 
This  book  is  DUE  on  the  last  date  stamped  below. 


"  i  h  1951 


SEP  28  1996 


LD  21-100m-9,'48(B399sl6)476 


\    V_/        \_^T    I    W« 


U.  C.  BERKELEY  LIBRARIES 


813219 


Library 
UNIVERSITY  OF  CALIFORNIA  LIBRARY 


